Executive Function and Language Comprehension in Traumatic Brain Injury

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Executive Function and Language Comprehension in Traumatic Brain Injury
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english
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Key-Delyria,Sarah Elizabeth
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University of Florida
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Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Communication Sciences and Disorders, Speech, Language and Hearing Sciences
Committee Chair:
Altmann, Lori J
Committee Members:
Lombardino, Linda J
Perlstein, William
Kaan, Edith
Cowles, Heidi

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Subjects / Keywords:
cognitive -- communication -- comprehension -- eeg -- erp -- executive -- language -- n400 -- p600 -- tbi
Speech, Language and Hearing Sciences -- Dissertations, Academic -- UF
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Communication Sciences and Disorders thesis, Ph.D.
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theses   ( marcgt )
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born-digital   ( sobekcm )
Electronic Thesis or Dissertation

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Abstract:
This study examined how cognitive components, such as attention and executive function, related to reading in traumatic brain injury (TBI) survivors and healthy young adults. Although the cognitive impairments associated with TBI are well documented, the relationship between different aspects of language functioning and cognition have not been thoroughly described. In fact, the relationship between different aspects of language processing and cognition has not been well documented in general. A pilot study was conducted with a control group hoping to describe the relationship between cognitive control and ambiguity resolution, but the results did not show a robust link. However, word-by-word processing interacted with ambiguity processing, which made the use of non-ambiguous materials necessary for use in the main study. This exploratory study examined behavioral and electrophysiological measures associated with reading using non-ambiguous sentences. Five TBI survivors and twenty-six healthy young adults completed a battery that included offline cognitive tasks, computerized reading comprehension measures, and the Attention Network Task (ANT). A word-by-word reading task and the ANT were completed during EEG recording. Unsurprisingly, whole sentences with anomalies were read at a slower rate than nonanomalous control sentences, and comprehension questions following anomalous sentences were responded to at a slower rate than nonanomalous control sentences. There was a different pattern of results for sentences presented word-by-word. RSVP sentences with semantic anomalies were judged incorrectly to be ?good sentences? at a poor accuracy rate in a subgroup of control participants and all of the TBI group. The TBI group was significantly less accurate on word-by-word sentence judgments, but not significantly slower, and they were not significantly less accurate on whole sentence comprehension, whole sentence reading time or RT as a group. There were several correlations between sentence measures and executive function, memory and vocabulary measures on the combined group data. There was not a robust N400, which is discussed in light of the poor RSVP semantic anomaly judgment accuracy and the type of stimuli used. There was, however, a measurable P600 response with group differences in amplitude and latency. As expected, there was also variability within the TBI group. This study confirmed that executive function, processing speed, working memory and vocabulary are related to sentence comprehension. Further, depression and immediate anxiety symptoms may affect sentence reading time and comprehension. The pattern of results also suggests that word-by-word processing is perhaps shallow overall due to the poor identification of semantic errors, which is consistent with the pilot study findings of shallow processing. Despite our small group of TBI participants and despite few significant group differences in cognition, we still found that the TBI group performed significantly worse on sentence processing measures. A larger study will be needed to take a more in depth look at cognitive processing and sentence processing. ERP measurements provide a promising avenue of exploring the variability within the TBI population on language measures and their relationship to behavioral performance. The relationships observed across the control and TBI groups have implications for many populations besides TBI, such as ADHD, Parkinson?s and schizophrenia.
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In the series University of Florida Digital Collections.
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Includes vita.
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Includes bibliographical references.
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Description based on online resource; title from PDF title page.
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This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Sarah Elizabeth Key-Delyria.
Thesis:
Thesis (Ph.D.)--University of Florida, 2011.
Local:
Adviser: Altmann, Lori J.

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1 EXECUTIVE FUNCTION AND LANGUAGE COMPREHENSION IN TRAUMATIC BRAIN INJURY By SARAH E. KEY DELYRIA A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR TH E DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2011

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2 2011 Sarah E. Key DeLyria

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3 To my boys: Dan, Isaac, and Jonah

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4 ACKNOWLEDGMENTS I would first like to thank my family for all of their support. I could not have gotten here withou t the support of my husband, my sons, my parents, or my grandparents. Though I can no longer tell him, I am particularly grateful for the support of my granddad, a great sponsor for the education of more than one generation of my family. I wish to acknow ledge and thank my committee members for their advice and help throughout all stages of this project. My mentor and chair, Lori Altmann, provided guidance and extensive comments at various stages of this project. William Perlstein shared the use of his lab his patient database and provided thoughtful technical support. Edith Kaan provided a great deal of expertise in the area of language ERPs and testing. Wind Cowles and Linda Lombardino helped me think through the logistics of what I was doing on numerous occasions. I appreciate all of their support. I am grateful for the help of several undergraduate volunteers including all of the Language over the Lifespan Lab volunteers. All the members of the lab provided helpful assistance particularly with stimuli development and pilot testing. Brittney Brezicki helped with data collection, data analysis and the interpretation of the pilot study. Ashley Atkinson and Jaclyn Grill helped extensively with stimuli development organizing the testing materials and collec ting the data. Finally, I am grateful for all of the participants that donated their time to help me complete my study. The small group of brain injury survivors was gracious in their willingness to share many details about a very personal period in their lives, and I am grateful for their support.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 8 LIST OF FIGURES ................................ ................................ ................................ ........ 10 ABSTRACT ................................ ................................ ................................ ................... 11 CHAPTER 1 GENERAL INTRODUCTION ................................ ................................ .................. 14 Summary and Relevance ................................ ................................ ........................ 14 Specific Aims ................................ ................................ ................................ .......... 17 Aim 1a ................................ ................................ ................................ .............. 17 A im 1b ................................ ................................ ................................ .............. 17 Aim 2 ................................ ................................ ................................ ................ 18 2 LANGUAGE PROCESSING AND COGNTION AFTER TRAUMATIC BRAIN INJURY ................................ ................................ ................................ ................... 19 Overview ................................ ................................ ................................ ................. 19 Epidemiology ................................ ................................ ................................ .......... 20 Clinical Characterization of Communication in TBI ................................ ................. 23 Language Research in TBI ................................ ................................ ..................... 25 Oral Language ................................ ................................ ................................ .. 26 Oral language production. ................................ ................................ .......... 26 Oral language comprehension. ................................ ................................ .. 31 Written Language ................................ ................................ ............................. 34 Language and Cognition in TB I ................................ ................................ .............. 37 Limitations of Previous Research ................................ ................................ ........... 40 3 EVENT RELATED POTENTIALS AND LANGUAGE PROCESSING ..................... 44 ERP Components ................................ ................................ ................................ ... 45 N400: Semantic Processing ................................ ................................ .................... 46 P600: Syntactic Processing ................................ ................................ .................... 49 LAN: Early Syntactic Processing ................................ ................................ ............ 53 Dissertation Study ................................ ................................ ................................ ... 55

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6 4 SENTENCE COMPREHENSION D URING RAPID SERIAL VISUAL PRESENTATION: A PILOT STUDY ................................ ................................ ....... 58 Overview ................................ ................................ ................................ ................. 58 Ambiguous Sentence Processing ................................ ................................ ........... 60 Cognition and Ambiguous Sentence Comprehension ................................ ............ 62 WM and Ambiguity ................................ ................................ ........................... 63 EF subcomponents: Pl anning ................................ ................................ .... 66 EF subcomponents: Shifting and conflict resolution ................................ ... 69 EF subcomponents : Inhibition ................................ ................................ .... 74 RSVP and Whole Sentence Presentation ................................ ............................... 76 Pilot Study Predictions ................................ ................................ ............................ 79 Pilot Study Methods ................................ ................................ ................................ 80 Pilot Study Participants ................................ ................................ ........................... 80 Pilot Study Neuropsychological Screening ................................ ....................... 80 Pilot Study Sentence Comprehension Tasks ................................ ................... 81 Pilot study materials ................................ ................................ ................... 81 Task 1: Whole sentence comprehension ................................ ................... 82 Task 2: RSVP sentence comprehension ................................ ................... 83 Results ................................ ................................ ................................ .................... 83 Pilot Study Discussion and Conc lusion ................................ ................................ ... 84 5 RESEARCH DESIGN AND METHODS ................................ ................................ .. 91 Overview ................................ ................................ ................................ ................. 91 Participa nts ................................ ................................ ................................ ............. 91 Cognitive Testing ................................ ................................ ................................ .... 92 Experimental Sentence Comprehension Tasks ................................ ...................... 94 Summary ................................ ................................ ................................ .......... 94 Materials ................................ ................................ ................................ ........... 95 Sentence Task 1: Whole Sentence Comprehension ................................ ........ 96 Sentence Task 2: RSVP Sentence Comprehension with EEG ......................... 97 EEG Procedures ................................ ................................ ................................ ..... 98 EEG Recording ................................ ................................ ................................ 98 EEG Analysis ................................ ................................ ................................ ... 99 6 RESULTS ................................ ................................ ................................ ............. 105 Overview ................................ ................................ ................................ ............... 105 Anxiety and Depression Screening ................................ ................................ ....... 105 Neuropsychological Battery ................................ ................................ .................. 105 ANT ................................ ................................ ................................ ....................... 106 Whole Sentence Comprehension ................................ ................................ ......... 106 RSVP Sentence Judgment ................................ ................................ ................... 107 Correlations among Sentence Mea sures ................................ .............................. 108 Correlations between Sentence Measures and Neuropsychological Measures ... 109 Event Related Potential (ERP) Data ................................ ................................ ..... 112

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7 N400 Component ................................ ................................ ........................... 113 P600 Component ................................ ................................ ........................... 113 7 DISCUSSION ................................ ................................ ................................ ....... 135 Reading Comprehension Performance ................................ ................................ 135 Comprehension and Cognition ................................ ................................ ............. 135 Depress ion and Comprehension ................................ ................................ .... 136 RSVP Performance and Cognition ................................ ................................ 139 The N400 and P600 ................................ ................................ ....................... 142 Clinical Implications ................................ ................................ ........................ 146 Limitations ................................ ................................ ................................ ...... 147 Conclusion ................................ ................................ ................................ ...... 149 APPENDIX A RSVP Sentence Stimuli without Comprehension Questions ................................ 150 B Whole Sentence Stimuli with Comprehension Questions ................................ ..... 156 C RSVP Sentence Fillers without Comprehension Questions ................................ .. 169 D Whole Sentence Task Fillers with Comprehension Questions .............................. 174 LIST OF REFERENCES ................................ ................................ ............................. 181 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 196

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8 LIST OF TABLES Table page 4 1 Sco res on Cognitive Tasks ................................ ................................ ................. 89 4 2 Sentence Types and Examples ................................ ................................ .......... 89 4 3 Scores on Experimental Sentence Tasks ................................ ........................... 89 4 4 Correlations between sentence comprehension performance and cognitive measures ................................ ................................ ................................ ............ 90 5 1 Participants with closed head injury ................................ ................................ 101 5 2 Demographic averages* ................................ ................................ ................... 102 5 3 Neuropsychological battery ................................ ................................ .............. 102 5 4 Sample sentenc es a from both sentence tasks ................................ .................. 103 6 1 Anxiety and Depression Screening Mean Scores by Group. ............................ 116 6 2 Neuropsychological Battery M ean Scores by Group. ................................ ....... 116 6 3 Wisconsin Card Sorting Task Mean Scores by Group. ................................ ..... 116 6 4 ANT Mean Scores by Group. ................................ ................................ ............ 117 6 5 Whole Sentence Comprehension Mean Scores by Group. .............................. 117 6 6 RSVP Sentence Judgment Mean Scores by Group. ................................ ........ 117 6 7 Correlations between RSVP Sentence Judgment, Whole Sentence Comprehension Performance and Self Paced Reading Time for Control Participants ................................ ................................ ................................ ....... 118 6 8 Corr elations between Sentence Performance and Neuropsychological Battery Performance ................................ ................................ ......................... 119 6 9 500ms window) for each stimulus type and region. ................................ ................................ ......... 120 6 10 Peak latencies (ms) for the N400 component (300 500ms window) for each stimulus type and region. ................................ ................................ .................. 120 6 11 V) for the P600 component (500 900ms window) for each stimulus type and region. ................................ ................................ ......... 121

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9 6 12 Peak latencies (ms) for the P600 component (500 900ms window) from the TBI group for each stimulus type and region. ................................ ................... 121 6 13 Summary of the 2 Group x 3 Stimulus x 3 Side x 2 Anterior/Posterior repeated measures ANOVAs performed on the N400 mean amplitude and latency data. ................................ ................................ ................................ ..... 122 6 14 Summary of the 2 Group x 3 Stimulus x 3 Side x 2 Anterior/Posterior repeated measures ANOVAs performed on the P600 mean amplitude and latency data. ................................ ................................ ................................ ..... 122

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10 LIST OF FIGURES Fi gure page 5 1 RSVP sentence presentation timing example.. ................................ ................. 104 5 2 Montage used for EEG analyses, showing the 64 channe l arrangement of the geodesic sensor net (EGI; Eugene, Oregon). ................................ ............. 104 6 1 Scatterplot of error and conceptual response percentages on the WCST for control and TBI groups to demonstrate the large number of outliers in the control group. ................................ ................................ ................................ .... 123 6 2 Scatterplot of RSVP Semantic Anomaly Accuracy and Digit Span Backwards performance for control and TBI groups to demonstrate the split in perf ormance on RSVP Semantic Anomaly Accuracy. ................................ ...... 124 6 3 Grand averaged nonanomalous, semantic anomaly, and syntactic anomaly ERPs from each electrode region examined for the control group. .................. 125 6 4 Grand averaged nonanomalous, semantic anomaly, and syntactic anomaly ERPs from each electrode region examined for the TBI group.. ....................... 126 6 5 Mean amplitudes for the N400 component. Error bars reflect the standard error of the mean. ................................ ................................ ............................. 127 6 6 Peak latencies for the N400 component. Error bars reflect the standard error of the mean. ................................ ................................ ................................ ...... 128 6 7 Mean amplitudes for the P600 component. Error bars reflect the standard error of the mean. ................................ ................................ ............................. 129 6 8 Peak latencies for the P600 component. Error bars reflect the standard error of the mean. ................................ ................................ ................................ ...... 130 6 9 P600 mean amplitudes shown separately for each group to show the Group x Stimuli x Side significant interact ion ( p= .02). ................................ ................. 131 6 11 P600 mean amplitudes shown separately for each group to show the Group x Anterior/Posterior x Side significant interaction ( p=. 03). ................................ 133 6 12 P600 peak latencies showing the Group x Side interaction ( p=. 06). ................ 134 6 13 P600 peak latencies showing the Stimuli x Anterior/Posterior interaction ( p< .01). ................................ ................................ ................................ ............. 134

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11 Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy EXECUTIVE FUNCTION AND LANGUAGE COMPREHENSION IN TRAUMATIC BRAIN INJURY By Sarah E. Key DeLyria August 2011 Chair: Lori J. P. Altmann Major: Communication Sciences and Disorders This study examined how cognitive components, such as attention and executive function, related to readi ng in traumatic brain injury (TBI) survivors and healthy young adults. Although the cognitive impairments associated with TBI are well documented, the relationship between different aspects of language functioning and cognition have not been thoroughly des cribed. In fact, the relationship between different aspects of language processing and cognition has not been well documented in general. A pilot study was conducted with a control group hoping to describe the relationship between cognitive control and amb iguity resolution, but the results did not show a robust link. However, word by word processing interacted with ambiguity processing which made the use of non ambiguous materials necessary for use in the main study This exploratory study examined behavio ral and electrophysiological measures associated with reading using non ambiguous sentences Five TBI survivors and twenty six healthy young adults completed a battery that included offline cognitive tasks, computerized reading comprehension measures, and the Attention Network Task (ANT). A word by word reading task and the ANT were completed during EEG recording.

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12 Unsurprisingly, whole sentences with anomalies were read at a slower rate than nonanomalous control sentences, and comprehension questions follo wing anomalous sentences were responded to at a slower rate than nonanomalous control sentences. There was a different pattern of results for sentences presented word by word. RSVP s poor accuracy rate in a subgroup of control participants and all of the TBI group. The TBI group was significantly less accurate on word by word sentence judgments, but not significantly slower, and they were not significantly less accurate on w hole sentence comprehension, whole sentence reading time or RT as a group There were several correlations between sentence measures and executive function, memory and vocabulary measures on the combined group data. T here was not a robust N400 which is di scussed in light of the poor RSVP semantic anomaly judgment accuracy and the type of stimuli used There was, however, a measurable P600 response with group differences in amplitude and latency. As expected, there was also variability within the TBI group. This study confirmed that executive function, processing speed, working memory and vocabulary are related to sentence comprehension. Further, depression and immediate anxiety symptoms may affect sentence reading time and comprehension. The pattern of resu lts also suggests that word by word processing is perhaps shallow overall due to the poor identification of semantic errors, which is consistent with the pilot study findings of shallow processing. Despite our small group of TBI participants and despite fe w significant group differences in cognition we still found that the TBI group performed significantly worse

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13 on sentence processing measures A larger study will be needed to take a more in depth look at cognitive processing and sentence processing. ERP m easurements provide a promising avenue of exploring the variability within the TBI population on language measures and their relationship to behavioral performance. The relationships observed across the control and TBI groups h ave implications for many pop ulations

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14 CHAPTER 1 GENERAL INTRODUCTION Summary and Relevance Reading comprehension is a complex skill that is known to require working memory (Myachykov, Tomlin, & Posner, 2005; Shaywitz et al., 2001; Ylvisaker, Szekeres, & Feeney, 2001) as well as language specific processing. However, the relative contributions of other cognitive processes, such as attention and executive function, are largely unknown. Because cognitive abilities can dissociate, there is a critical need to understand how different aspects of cognition contribute to reading. One way to investigate the relative contribution of attention and executive function to reading would be to use a population with acknowledged deficits in bot h attention and executive function, such as individuals with traumatic brain injury (TBI). As a step in this direction, the current study addresses the question of whether attention and executive function contribute to sentence comprehension during reading in readers with and without TBI. Second, this study addresses the question of whether any reading comprehension problems in TBI reflect an underlying language processing impairment, by taking advantage of the temporal specificity of event related potentia ls ( ERPs ) and the sensitivity of the N400 a nd P600 ERP components to language (Duncan et a l., 2009; Hagoort & Brown, 2000) Over five million people are living with traumatic brain injury (TBI) related disability in the United States with an additional 80,0 00 people becoming disabled due to TBI each year (N.H.I. Foundation, 2006; Thurman, 1999). According to the N.H.I. Foundation, c ognitive impairments, such as executive function, attention, memory, and language, are primary contributors to disability in thi s population. Although cognitive

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15 problems have been well studied in TBI (Brooks, Fos, Greve, & Hammond, 1999; Chan, 2000, 2005; Chan, Hoosain, Lee, Fan, & Fong, 2003; Cicerone, 1996; Perlstein, Larson, Dotson, & Kelly, 2006; Pero, Incoccia, Caracciolo, Zoc colotti, & Formisano, 2006; Whyte, Polansky, Fleming, Coslett, & Cavallucci, 1995), there are few investigations of reading processes (Ferstl, Guthke & von Cramon, 2002; Schmitter Edgecombe & Bales, 2005; Ylvisaker et al., 2001). The scarcity of studies is surprising given that attention and executive functioning are necessary for reading (Myachykov et al., 2005; Shaywitz et al., 2001; Ylvisaker et al., 2001), and that these abilities are often impaired in TBI (Bittner & Crowe, 2006, 2007; Body & Parker, 2005; Brooks et al., 1999; Chan, 2000, 2005; Chan et al., 2003; Chobor & Schweiger, 1998; Cicerone, 1996; Leblanc, de Guise, Feyz, & Lamourreux, 2006; Moran & Gillon, 2004; Moran, Nippold, & Gillon, 2006; Perlstein et al., 2006; Pero et al., 2006; Turkstr a, 1998; Whelan & Murdoch, 2006; Whyte et al., 1995). Impaired reading can impact a variety of instrumental activities of daily living, as well as the ability to be successfully reintegrated into the workplace or school (Leblanc et al., 2006; Ylvisaker et al., 2001). Thus, there is a critical need to understand how attention and executive function impairments contribute to reading in TBI as well as whether there are additional solely linguistic impairments impacting reading performance. The introductory ch apter s that follow present first, a review of the literature addressing language and cognition in TBI survivors in order to show that there are documented deficits but the deficits have not been thoroughly researched A short section describing the relatio nship between language deficits and cognitive deficits in

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16 TBI survivors is also included. S econd, the ERP components that are being studied are described A pilot study is then presented that compared rapid serial visual presentation (RSVP: word by word p resentation) of sentences and whole sentence presentation along with a battery of cognitive tasks RSVP is typically used in ERP studies of sentence processing because the word by word presentation makes it possible to time lock the EEG signal to each word in the sentence. However, RSVP is thought to tax cognition, particularly working memory, because a reader does not have the entire sentence available at once as is typical during reading. Problems associated with presentation type might be exacerbated in a population like TBI with known cognitive deficits. The pilot study was conducted to determine if the different methods of stimulus presentation type had different effects on reading comprehension and if these differences were related to individual differ ences in cognition in a group of healthy non neurologically impaired undergraduates. The pilot study used ambiguous sentences because resolving ambiguity requires the suppression of an initial interpretation and the activation of the correct interpretation This suspected pattern of suppression and activation suggests a relationship to executive function which is often impaired in TBI. Ambiguous sentences were the original stimuli that were to be used with the main study. However, because RSVP seemed to wo rsen performance on ambiguous sentence comprehension disproportionally when compared with non ambiguous sentence comprehension, the main dissertation study did not include ambiguity. Because of the differences found in this pilot study, sentence comprehens ion in TBI was assessed using both whole sentence presentation and RSVP, with only the latter

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17 method used during the ERP experiment. The dissertation study which is presented following the pilot study, addresses the specific aims described below. Specifi c Aims My long term research goal is to investigate the contribution of executive function components on aspects of language use using TBI as a model population. A secondary goal is to delineate the range of impairments of language use across modalities in TBI, with the intent of providing experimental data to support evidence based practice in speech language pathology. The specific objective of the proposed research is to define the relationship between sentence comprehension, attention and executive func tion in individuals with TBI. The central hypothesis is that both attention and executive function are related to reading but that there is an additional linguistic processing speed or linguistic integration component that also may be impaired that is inde xed by the N400 for semantic processing and the P600 for syntactic processing. To address this hypothesis, I tested individuals with and without TBI on a battery of neuropsychological tasks and sentence comprehension tasks done with and without electroence phalography ( EEG ) recording in order to pursue the following specific aims. Aim 1a Determine whether sentence reading time and comprehension are impaired in TBI survivors relative to matched controls. The working hypothesis is that sentence reading will be slowed and comprehension impaired in TBI survivors It is also predicted that performance will be variable within the impaired group. Aim 1b Determine whether cognitive impairments of specific components of attention, working memory or executive function predict comprehension performance in TBI

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18 survivors. The working hypothesis is that different types and severities of cognitive impairment will relate to measures of reading. For example, impairment of executive function may be related to performance on syn tactically anomalous sentences, and impairment of working memory may better related to performance across all sentence types Aim 2 Determine whether typical electrophysiological markers of sentence processing (e.g. N400, P600) differ in mean amplitude and latency between the group of participants with TBI and the group of control participants. The working hypothesis is that sentence processing metrics will differ between groups. Due to the heterogeneous nature of brain injury from TBI, impairment levels fo r cognition and language may differ between participants even when severity levels as measured by length of loss of consciousness and coma scores may be similar Amplitude differences are expected between groups It is also predicted that the standar d EEG components associated with language processing will be delayed in TBI survivor s relative to healthy controls.

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19 CHAPTER 2 LANGUAGE PROCESSING AND COGNTION AFTER T RAUMATIC BRAIN INJUR Y Overview Communication impairment in survivors of traumatic brain injury ( TBI ) profoundly influences their successful return to social, vocational, family and educational settings. Coworkers and supervisors of TBI survivors have frequently cited poor communication as a major impediment to workplace success (Leblanc et al., 200 6; Ylvisaker et al., 2001). Despite the public health relevance, however, treatment of poor communication following a TBI has not been closely examined through research, and treatment outcomes are often poor (Ylvisaker et al., 2001). There have been very f ew treatment studies overall, and the few theoretically based treatments have not been shown to result in generalization or significantly improve d long term functioning (Cannizzaro & Coelho, 2002; Coelho, Grela, Corso, Gamble, & Feinn, 2005; Ylvisaker et a l., 2001). The paucity of treatment studies is probably due to the general lack of research in this area. The research literature, which mostly addresses discourse level impairments, is a confusing mix of observational case studies and groups with a wide r ange of possible deficits. The wide range of deficits is typical of this heterogeneous population It is difficult to determine if there is a shared underlying language deficit common across these studies, especially because they have mostly made conclusio ns about comparisons between a highly heterogeneous TBI group and a control group or single case studies. Group studies are important, but the diversity of injury etiology, severity, and post onset time at the time of study are important to take into accou nt. Comprehensive, efficient and relevant assessments and treatments are therefore difficult to develop. The relationship between language and cognition has also not been

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20 well described in TBI survivors despite the prevailing notion that cognitive deficits are the most likely cause of communicatio n impairments (Hinchliffe, Murdoch & Chenery 1998; McDonald, Togher & Code, 1999). After describing the basic epidemiology and clinical language characteristics of TBI, this chapter will review the available resea rch describing the oral and written language of TBI survivors and how it may relate to cognition. Epidemiology Over five million people are living with TBI related disability in the United States. An additional 1.5 million people sustain a TBI each year wi th 50,000 deaths and 80,000 people becoming disabled annually (N.H.I. Foundation, 2006; Thurman, 1999). These figures do not include the more than 10% of wounded soldiers returning with TBI from current U.S. military engagements (Fischer, 2007). Hospitaliz ation rate for TBI is highest among males, 15 24 years of age and over age 65 (Thurman, 1999). In 2000, the medical costs and indirect costs related to lost productivity were estimated to be $60 billion (N.H.I. Foundation, 2006). Impaired executive functio n, attention, memory, and language, are primary contributors to disability in this population with a high amount of variation from person to person due to the heterogeneous nature of TBI (N.H.I. Foundation, 2006). TBI encompasses a wide range o f causes of damage, lesion sites and types, as well as many levels of severity. TBIs include any brain injury caused by trauma other than disease or substance abuse. These injuries can be either open or closed head injuries. Open, or penetrating, head inju ries occur when a foreign object, including a bullet or skull fragment, enters the brain tissue. Closed, or blunt, head injuries most often occur when the head encounters rapid acceleration and

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21 deceleration, such as during a motor vehicle accident or fall. Closed head injuries are the most common type of head injury and result in diffuse, multi focal brain injury. Deficits can be widespread and are very different from the more focal lesions resulting from penetrating injury or cerebrovascular accident. Clos ed head injuries are the focus of this study, and the term TBI used here will refer to closed head injuries unless otherwise specified. Concussion is by far the most common type of head injury comprising at least 75% of head injuries (Marsh & Smith, 1995; Wiebe, Comstock & Nance, 2011). It often involves a transient loss of consciousness and, instead of focal neurological deficits, symptoms include a wide array of physical and cognitive complaints. Headaches, fatigue, dizziness, sensitivity to noise, inabil ity to concentrate and poor memory are just a few of the typical post concussive symptoms. Language impairments have also been documented in a small number of studies (Marsh & Smith, 1995). Though these initial post concussive symptoms typically resolve wi thin a few months, subtle cognitive dysfunction may persist and emerge only under conditions of stress or further injury (Marsh & Smith, 1995; Wiebe et al., 2011). There is not a commonly used clinical scale for describing concussion severity due to the he terogeneous nature of the injuries, symptoms and recovery (Wiebe et al., 2011). People who have had a concussion may not always notice mild symptoms after the initial 6 month recovery period due to coping mechanisms that are not fully understood (Marsh & S mith, 1995). Moreover, it is not well understood how to determine when it is safe for a person who has sustained a concussion to return to normal activities, including activities requiring cognitive tivities, including school, work,

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22 and especially sports prematurely raises the risk for persistent post concussive symptoms, future concussion, and in rare cases, death. The extent and severity of neural damage following TBI is not always adequately ident ified through CT or MRI scans, because a large proportion of the overall damage is often at the level of individual neurons. Contusions and focal areas of bleeding can be seen in a scan, but diffuse axonal injury is common and not always associated with bl eeding. Without overt bleeding, the damage is much more difficult to capture with clinical diagnostic imaging. Therefore, coma indices and post traumatic amnesia (PTA) duration are often used to describe severity, because they have been shown to accurately predict the course of recovery from impairments (Chapman, 1997). There are certain brain regions thought to be more vulnerable to TBI. Memory impairments are the most common following head injury, because the hippocampal neuronal cells are particularly su sceptible to oxygen deprivation (Prince, 1983), and because the frontal and temporal lobes are susceptible to structural injury. Specifically, the bony protrusions in the frontal brain case, especially the sphenoid bone, can cause tearing and scraping of t he brain during injury and following injury if there is significant swelling (Bigler, 2001). The frontal lobes are involved in many complex cognitive tasks, including language processing (Friedland & Miller, 1998; Hinchliffe et al., 1998; Whelan & Murdoch 2006). The impairments due to diffuse brain damage are difficult or impossible to predict because diffuse damage is difficult to capture with brain imaging. Without imaging, it is difficult to predict the affected brain regions. Therefore, c omprehensive neuropsychological assessment is one of the tools used to identify areas of impairment in TBI survivors even in the absence of clear findings via brain imaging. Language

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23 assessment during neuropsychological evaluation is typically only cursory In fact, a full language evaluation by a speech language pathologist is relatively rare and limited by the scarcity of available language assessment tools. Therefore, improving understanding of cognitive and language impairments and how they relate has the potential to greatly improve the rehabilitative care of TBI survivors. Clinical Characterization of Communication in TBI The American Speech Language Hearing Association (2005) specifically n impairment in TBI. Because a phasia is considered to be impairment sp ecific to linguistic processing, t he language impairments in TBI are usually non aphasic in nature (McDonald et al., 2000 ) Indeed, any communication impairments are usually considered s econdary to cognitive impairments (Hinchliffe et al., 1998). Difficulty with complex comprehension or connected speech following a TBI is often attributed to processing speed, executive function, or another cognitive deficit unless it occurs following dama ge to a known language area or in the absence of tested cognitive deficits. Test batteries for language in adults, most of which have been designed to assess aphasia, do not adequately identify the more complex, sometimes subtle communication problems obse rved in TBI survivors (McDonald et al., 2000). The development of standardized tests to identify communication impairments in TBI is limited by an incomplete understanding of both the range of possible impairments and the extent to which communication impa irments stem from language specific deficits or are secondary cognitive deficits. Despite an expectation of communication problems following TBI, assessment of language in TBI must often be improvised by clinicians due to a lack of available resources. Th e Academy of Neurologic Communication

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24 Disorders and Sciences (ANCDS) has published guidelines for TBI assessment (Coelho, Ylvisaker & Turkstra, 2005; Turkstra, Ylvisaker, Coelho, Kennedy, Sohlberg, Avery, et al., 2005), but the majority of tests examine co gnitive and neuropsychological status, rather than language use. Further, the majority of these tests have not been developed or standardized for use with TBI patients. The ANCDS recommendations for testing basically state to use tests cautiously and in co njunction with a variety nonstandardized measures such as functional reading comprehension, conversation pragmatic awareness, and especially discourse analysis. Nonstandardized measures are typically a part of a dynamic clinical assessment given by any spe ech language pathologist, but the complexity and time intensive measures needed to provide a complete picture for the impairments following TBI make them unlikely to be regularly or consistently administered. Oral language production and comprehension hav e both been observed to be impaired in TBI survivors (Hinchliffe et al., 1998). Hinchliffe and colleagues found statistically significant differences between TBI survivors and control participants on most subtests and specific items from a large battery of standardized language tests but performance by TBI survivors was not always below clinical cutoffs for identifying impairment. In a clinical setting, whether performance on the se standardized measures merits speech rehabilitation depend s on the clinician and possibly on whether insurance coverage is contingent on performance on normed tests Further, as mentioned in the ANCDS guidelines (Turkstra et al., 2005), performance on the recommended measures has not been shown to have functional sign ificance. In particular, they do not fully address the complex problems with reading, conversation,

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25 and discourse which, though central to everyday functioning are not routinely identified in standardized tests Written language has also been found to be impaired in TBI (Hinchliffe et al., 1998), though it is usually a secondary concern in the face of more immediately disabling oral language impairments. However, complex reading comprehension may be a particular challenge for TBI survivors hoping to retur n to school or work. As discussed, there are few available tests that identify complex reading impairments in adults and even fewer that are intended for use with TBI. The development of c linical assessments and treatments for language in TBI has been limi ted by a lack of knowledge about the variety of language deficits observed in TBI; consequently, initial research should aim at delineating the range of language deficits and severity range of these deficits in this population so that appropriate assessm ents and treatments can then be developed. Language Research in TBI There is a growing body of research into the language characteristics of TBI survivors. The bulk of research to date has attempted to describe the impaired discourse production and compr ehension particularly involving communication pragmatics because these deficits are most common ly noticed by both clinic ians and others who interact with them. However, research on other aspects of language is extremely limited including the interaction between cognitive impairments and language, the focus of this study Below is a review of the research characterizing oral and written language use in studies of TBI survivors as well as studies that have explicitly addressed relationship s between cogniti ve and linguist function s in this population

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2 6 Oral Language Oral language production. Verbal fluency and anomia are the two most commonly reported oral language production impairments following TBI in the research literature (Butler Hinz Caplan & Waters 1990; Goldstein et al. 1994; Gruen, Frankle & Schwartz, 1990; Hinchliffe et al., 1998; Levin Grossman, Sarwar & Meyers 1981) possible due to the frequency and ease of testing them Fluency tasks involve the rapid generation of words within one minute words within the specified category, and it is not uncommon in clinical settings to find that they switch letters or semantic categories very early in the task (e.g., begin with the or ask repeatedly for task instructions Verbal fluency is typically used to measure processing speed and word associate generation (e.g., Controlled O ral Word Association Test, Benton, Sivan, Hamsher, Varney & Spreen 1994; Gruen et al., 1990), and it has been found to correlate with some language measures such as sentence interpretation (see Hinchliffe et al., 1998). However, it does by no means consti tute a thorough or adequate assessment of language processing. Anomia refers to the inability to retrieve and produce words. It is not unique to TBI, and it has been a focus of research in stroke survivors for decades (Chapey, 2001). Although anomia is the most commonly reported language impairment following TBI ( Butler Hinz et al. 1990; Goldstein et al., 1994; Gruen et al. 1990; Hinchliffe et al., 1998; Levin et al. 1981 ) it has not been a particular focus for research in this group. Anomia is often ac companied by secondary behaviors such as paraphasia s and circumlocution s Paraphasias include phonological or phonemic substitutions (e.g.,

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27 neologistic substitutions maladaptive and are usually noticeable by communication partners. Circumlocution involves speaking around, defining or otherwise describing a difficult to retrieve word. For example, if a patient is and is often encouraged in therapy. It is also often used by non brain injured adults as a normal word ret rieval strategy and is, therefore, not always noticed by communication partners unless the circumlocutions are inappropriate Circumlocutions may lead to or underlie disco urse level impairments (Friedland & Miller, 1998 ). For example, in a case study, Fri ed land and Miller (1998 ) found that circumlocutions often led to involved sudden shifts into a new topic which resulted in the communication partner having difficulty following the topic. However, this association between conversational breakdown and word retrieval was only noticed after extensive conversational analysis. Discourse impairments are difficult to predict from more basic formal testing focusing on phonology, naming or syntax, even when these processes are impaired Conversational impairments, s uch as covert topic shifting and self repairs, could be directly related to impairments of different aspects of language Discourse in TBI survivors has received relatively more attention in the research literature than other aspects of language, because it is often the most noticeabl e and debilitating communication impairment. Thus, d etailed discourse analysis is considered to be a useful tool for developing treatment plans for TBI survivors (Coelho, Liles & Duffy, 1991b; Coelho Ylvisaker et al., 2005; T urkstra et al., 2005). Discourse

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28 impairments in conversation and various types of monologues have been observed, including: disorganization, incomplete story episodes, tangential language, disinhibition and socially inappropriate language (e.g., Biddle, Mc Cabe, & Bliss, 1996; Body & Parker, 2005; Coelho, 2007; Coelho et al., 1991b; Coelho Grela et al., 2005; Leblanc et al, 2006; Snow, Douglas, & Ponsford, 1999). Other analyses have shown that TBI patients produce the same quantity of discourse as controls, but the quality of the discourse is typically worse due to false starts, fillers and repetitions (Biddle et al., 1996). Additionally, Coelho Grela and colleagues (2005) reported that their participants with TBI produced fewer propositions per T unit (an independent clause with all associated subordinate clauses). That is, they produced less information and required more words to do it These discourse problems in TBI survivors often put a significant burden on their listening partners. Children and adoles cents face many of the same language production difficulties as adults following TBI, such as anomia and impaired fluency (Chapman, 1997), although the severity of these may vary depending on their level of language development prior to injury. In personal narratives, children with brain injury provided less information overall, including central ideas, with less organizational structure over the course of the story than age matched, non brain injured children (Chapman, 1997). Impairments may show up later in development as well when increasing levels of complexity are required for communicating in social or educational settings (Biddle et al., 1996). Unfortunately, in the published literature on discourse production in TBI, there has been little overlap in methods of data collection, participant inclusion criteria or analysis

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29 methods between studies of discourse making it difficult to directly compare studies. Discourse elicitation methods have included conversation (Body & Parker, 2005), story retelling fr om picture sets (Coelho Grela et al., 2005), story generation from a single picture (Coelho Grela et al., 2005), and conversational mapping (Biddle et al., 1996) among others. Moreover, few studies have included a comparison or control group to help gaug e the relative degree of impairment (Hinchliffe et al., 1998) Also, many reports of language or discourse functioning following TBI have been case studies (e.g., Body & Parker, 2005). The latter problem is particularly serious in this population due to th e extreme heterogeneity of impairment seen across individuals. Despite the disparate methods used to elicit discourse, and the different procedures used for discourse analysis it is generally agreed that discourse level impairments can persist for years after an initial injury (Coelho, 2007). Based on this assumption, many of the studies looking at discourse have included patients with a wide range of post onset times. For example, Biddle and colleagues (1996) limited testing to individuals with a post on set time of 1 year or under, whereas Coelho Grela and colleagues (2005) included individuals who spanned a range of 1 99 months post injury. This range is surprising considering that it is typical in the aphasia literature to wait until at least 1 year fo r inclusion in research studies because of the often rapid during the first year post onset of injury If the goal of the study is to characterize the population, or determine what deficits are most likely to impact quali ty of life for TBI survivors, testing should be done after an initial, relatively standard recovery period. Further, the acceptance of discourse analysis as a widely used clinical tool is currently unlikely, because formal discourse analysis is more time

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30 c onsuming, complex and less reliable than testing of lower level language skills such as sentence comprehension or picture naming which do not require lengthy transcriptions and specialized language analysis skills. Clinicians are therefore less likely to a ttempt a formal analysis of discourse, even if they do include in their diagnostic reports their impressions of the adequacy of the discourse based on their conversation with a TBI survivor. In contrast to discourse, little is known about impairments affec ting more basic aspects of language following TBI. In a search of the literature, only one study was found that formally tested language production of a group of TBI survivors beyond naming ability. Hinchliffe and colleagues (1998) tested 25 closed head in jury patients that were between 2 and 9.75 months post onset of injury, and these patients were compared to 23 control participants. All participants were tested on a norm referenced, large battery of 10 language and at least 12 cogniti ve measures across 2 4 sessions. TBI patients were significantly worse than control participants on w ord naming from the Boston Naming Test ( Kaplan, Goodglass & Weintraub 1983 ) and the Western Aphasia Battery (Kertesz, 1982), and Oral Expression from the Test of Language Com petence (Wiig & Secord 1989). Notably, the Oral Expression subtest required participants to produce statements or questions that would be appropriate to an individual pictured in a certain social situation, supporting other reports in the literature of im pairments in the pragmatics of language in TBI patients (Channon & Watts, 2003; Davis, 2007; McDonald, 1993). In contrast, the repetition of words and sentences was not significantly different from control participants. These were the only oral production measures that were analyzed These limited results

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31 suggest that some aspects of language production may be impaired in individuals with TBI and deserves further study. In summary, oral production of language is actually the most widely studied aspect of language in survivors of TBI. Most of the work has focused on discourse production, which has been found to be impaired in several dimensions Lower level language production impairment of sentences and single words ha ve also been documented (Hinchliffe et al., 1998) but they have not been thoroughly studied. While the range of discourse difficulties are usually attributed to cognitive deficits, as will be discussed in a later section discourse problems may also stem fro m language deficits. Friedland and Miller (1996) attributed discourse level problems to naming difficulties in a single patient. Much more work is needed to improve assessment and treatment of language production in TBI survivors. Oral language comprehensi on. Less research has focused on oral language comprehension (Coelho Grela et al., 2005; Hinchliffe et al., 1998; Moran & Gillon, 2004; Turkstra, 1998; Turkstra & Holland, 1998) than production deficits in TBI Occasionally it has been argued that syntac tic comprehension is generally preserved in TBI survivors (Angeleri, Bosco, Zettin, Sacco, Collie & Bara, 2008; Coelho, 2002); however, a wide variety of comprehension impairments mostly involving complex comprehension, have been documented in other studi es (Coelho, Liles & Duffy, 1991a; Hinchliffe et al., 1998; Levin et al., 1981; Nicholas & Brookshire, 1995). Hinchliffe et al ( 1998) found that adults with TBI were consistently and significantly impaired on tests requiring complex comprehension but not o n tests of s imple r comprehension. Specifi c ally the comprehension subtest of the Western

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32 Aphasia Battery (WAB; Kertesz, 1982) did not show significant differences between groups. The WAB includes sentences that are difficult in terms of length and the nece include complex ambiguity or other particularly difficult syntactic structures (f or example, it does not include passives or relative clauses). In contrast, a dults with TBI performed significantly worse on the token test (in which individuals rearrange colored shapes according to increasingly complex oral directions), ambiguous sentenc e comprehension ( requiring recognition and interpretation of distinct meanings for each single sentence from the Test of L anguage Competence Expanded; TLC E ; Wiig & Secord, 1989 ), and listening comprehension (requiring an inference to be made from two caus ally related events from the TLC E). A number of other comprehension deficits were noted, but it was unclear whether or not those deficits were documented in the oral or written modality. These findings suggest that syntactic comprehension is impaired but only for more complex structures, at least for the relatively recently injured as were tested in onset). Butler in a gr oup of people with acquired head injury associated with a variety of lesion sites and etiologies. They looked at 17 closed head injury, 16 stroke patients and 20 control participants to observe syntactic processing performance on 14 types of sentences with a range of complexity. Complexity was varied according to the number of verbs, number of thematic roles assigned by the argument structure, and canonicity of word order. Participants were required to manipulate toy objects to illustrate the meaning of

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33 sen tences they heard Complex syntactic processing appeared to be problematic for both brain injured groups based on poor accuracy of responses to sentences with noncanonical thematic role assignment as comprehension of passives and cleft object was worse t han actives In addition, comprehension of sentences in which verbs assigned m ore than two thematic roles was impaired; for example dative passives were comprehended worse than passive conjoined agent sentences Also, comprehension of sentences containing t wo or more verbs such as subject subject relative sentences were impaired relative to active conjoined theme sentences Only the number of nouns in a sentence did not appear to affect performance, suggesting that syntactic deficits may not be simply rel ated to amount of semantic content. The stroke and TBI survivor groups did not differ from one another on these factors, and site of lesion did not appear to play an important role in comprehension performance The bulk of the research on comprehension im pairments in TBI has been limited to discourse comprehension, especially figurative language comprehension in adolescents with TBI (Moran & Gillon, 2004; Turkstra, 1998; Turkstra & Holland, 1998). For example, processing of lexical ambiguity (i.e. words wi th more than one meaning such as, letter ) has been observed to be impaired in both children (Dennis & Barnes, 1990) and adults with TBI (Chobor & Schweiger, 1998) in single words and in discourse. Other studies have demonstrated that certain patients hav e difficulty interpreting humor, irony, deceit and other metalinguistic uses of language (Angeleri et al., 2008; Hinchliffe et al, 1998). Certain discourse skills that rely on comprehension have been shown to be impaired as well. For example, drawing corre ct inferences from stories has been shown to be impaired (LeBlanc et al., 2006). Additionally, Chapman (1997) found that adolescents

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34 with TBI were poor at paraphrasing, summarizing and identifying the main point of a story. These types of discourse compreh ension assessments rely on both comprehension and production skills, and deficits in these two skills may interact. That is, appropriate discourse production requires comprehension of discourse cues relating to situation and topic. Based on the few studie s that have directly addressed oral language comprehension, complex comprehension has been shown to be significantly impaired. In addition, Butler Hinz and colleagues (1990) found that complex comprehension impairments seemed to be related to structural co mplexity and not simply sentence length. Metalinguistic comprehension, discourse comprehension and lexical ambiguity comprehension all also have been shown to be impaired. Written Language Written language production has received little attention in the l iterature on TBI survivors and language. Levin et al. (1981) noted that written language production impairments may be present following TBI, but to my knowledge, no research studies have documented or described it in TBI survivors. However, reading, has b een directly addressed by a handful of studies. Reading is a particularly important skill that is often overlooked in this population possibly because it has not usually been a focus in traditional adult language rehabilitation. Moreover, a dult language re habilitation efforts have traditionally been associated with stroke survivors and reading is not usually high on the list of therapeutic targets. For the typical young adult TBI survivor, however, reading impairment is more likely to interfere with an att empt to return to work or school. Reading is important to the quality of life of brain injury survivors, and it is also the focus of my study.

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35 Reading requires the integration of multiple skills from language comprehension to visual processing. It is not s urprising, then, that there is a general expectation of impaired reading along with anecdotal clinical evidence of frequent reading difficulty in TBI survivors. Hinchliffe and colleagues (1998) found reading comprehension to be impaired in TBI survivors wh en compared with control participants based on a single measure of reading comprehension from the Boston Diagnostic Aphasia Examination (Goodglass & Kaplan, 1983) Frattali and colleagues (2007) examined the processing of written lexical ambiguity in a gr oup of 25 patients with prefrontal cortex damage. Nineteen of the patients had a history of penetrating head injury, three of tumor resection, and three of stroke. Eleven of the participants had bilateral damage, six had right hemisphere damage, and eight had left hemisphere damage. S ubgroups were based on the location of damage, not etiology, and were analyzed both together and separately. Sentences were presented in two phrases with a target word presented after the first phrase. For example, participants decide whether that single word, presented mid sentence, was related to the meaning of the sent ence or not. The word immediately preceding the test word was a noun verb related stimuli were unrelated to the target word, and the test words in the sentence w ere not

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36 homonymous. Two presentation timing conditions were also used: immediate and delayed. In the immediate condition, a formula allowed for a set presentation rate based on the number of characters and words in each phrase. In the delayed condition, a 1500ms constant was incorporated into stimulus onset time. Participants with prefrontal damage were less accurate in distinguishing between inappropriate and appropriate words. Surprisingly, however, when the sentence stimuli were presented at slower inter vals, the control group showed increased interference and the group with prefrontal damage showed decreased interference. These results were based on a suppression ratio calculated by subtracting the mean RT to unrelated words from the mean RT to wrong mea ning words divided by the mean RT to unrelated words. That is, when compared to the prefrontal damage group, it took the control group longer to decide about words with the incorrect meaning than unrelated words in the delayed relative to the immediate con dition. Frattali and colleagues discussed their results in terms of control versus automatic processing in the prefrontal cortex. They suggested the results could be attributed to a ge (which included all participants with brain damage of any kind) automatic processing of semantic relatedness. The finding that bilateral damage resulted in the worst performance when compared with left or right unilatera l damage led Frattali and colleagues to propose that the left hemisphere is involved with lexical meaning selection while the right hemisphere is important for lexical ambiguity resolution. This study had several limitations, including the wide range of ag es tested and the lack of a reported post onset time for the brain injury. The control group was

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37 reported to not vary in age from the group with brain injury (mean was 52.76), but the range of ages for the controls was not reported. This is a significant d rawback to the findings because the range in the group with brain injury was 38 to 68. Normal aging has been reported to result in changes to the prefrontal cortex and inhibitory responses in the literature (Hasher & Zacks, 1979) I n this study, there were enough younger adults that age based subgroups may have provided useful information. Their findings of language function are in line with the predominant theories of prefrontal cognitive function and therefore a valuable contribution to the sparse literat ure on language comprehension following TBI. A paucity of research looking at written language is not unique to the TBI literature; it has also not been well described in the aphasia literature, with most studies presenting single cases. However, the expec tations regarding language impairment in aphasia and TBI differ: f ollowing stroke, there is the expectation of language disability and therefore, stroke survivors are routinely evaluated by therapists. Following TBI, any apparent language impairment is oft en expected to resolve on its own, and therapy time is limited even during the acute stages. Written comprehension is an essential skill for people hoping to return to school and work after a head injury, which the small body of evidence suggests is impair ed in TBI survivors. More research is needed to both prove the existence of and raise awareness of language deficits. Language and Cognition in TBI This section will describe the studies that have looked specifically at the relationship between language a nd cognition in TBI survivors. Although cognitive communication deficits are the hallmark deficits of TBI, little research has been done to explicitly address the relationship between cognition and language use in this

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38 population. However, this is not surp rising because while there is quite a lot of research looking at language and working memory in non neurologically impaired adults (e.g., Just & Carpenter, 1992; Kemper & Sumner, 2001; MacDonald & Christiansen, 2002; Waters & Caplan, 1996) other aspects o f cognition have only recently been addressed in relation to language more systematically The relationship between cognition and language in normal adults will be addressed in the pilot study described in Chapter 4. Coelho (2002) found modest correlations between the Wisconsin Card Sorting Test (WCST), a measure of executive function, and measures of discourse complexity in story narratives No significant correlations were seen between any aspect of WCST performance and cohesion, an aspect of discourse or ganization based on the lexical and grammatical links that hold a text together. A separate study by Youse and Coelho (2005) looking at a large 55 person sample also only found modest correlations between scores from the Wechsler Memory Scale (WMS) and mea sures of discourse based on story generation and retelling. They measured the number of episodes (i.e. an initiating event, an action, and a direct consequence marking a goal), the number of complete ties out of total ties (i.e. a measure of cohesion in wh ich the listener must find the meaning for the tie outside of the sentence), the number of T units (i.e. an independent clause plus any associated subordinate clause) within an episode, and the number of words and subordinate clauses per T unit. The WMS me asures they used were digit span, logical memory, and associate learning. Digit span was only correlated with the number of subordinate clauses per T unit in the generation task, and associate learning was correlated with the number of words and subordinat e clauses per T unit, the number of episodes, and the complete ties out of total ties in the retelling task.

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39 Logical memory was not correlated with any of their measures. These results are surprising in that working memory and discourse deficits are a comm on concern following TBI, but their language and cognitive measures may not have been complex enough to show a relationship. Youse and Coelho discuss ed the need for a more complex working memory measure, such as the reading span, as well as a more varied s et of discourse measurements. It is not clear whether or how they controlled for the wide variety of severities or ages in their sample. However, their results do suggest that there may be different relationships between different types of linguistic tasks and cognitive tasks following a TBI. Links between working memory and discourse performance in adolescents with a history of TBI have also been observed. A series of studies by Moran and colleagues found that the working memory demands affected performanc e (Moran & Gillon, 2004, 2005; Moran, Nippold & Gillon, 2006) They pointed to the necessity of accounting for the storage demands of a task which they found affected comprehension Furthermore, when the storage demands were minimized, in the case of infe rence comprehension (Moran & Gillon, 2005), performance markedly improved. In some cases, comprehension was poor or reduced regardless of storage demands, but a demanding working memory component to the task weakened performance. Additionally, Channon and Watts (2003) found a relationship between the executive function of inhibit ion and the accuracy of judgment of the social appropriateness depicted in several short stories. The authors of these studies suggested that further research should take a wider va riety of language and cognitive abilities into account.

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40 A large battery of linguistic and neuropsychological tests was used in the study by Hinchliffe and colleagues (1998), discussed above, in order to address the relationships between many aspects of la nguage and cognition. They found several promising relationships, though only correlational analyses were used. Working memory tasks were more closely associated with basic auditory comprehension (e.g. Token Test) than with processing more complex language (e.g. humor comprehension). They argued that this was because memory was associated with processing and storage and not conceptual integration. Lexical semantic processing as tested by asking about synonyms, antonyms, definitions and semantic associates, however, was associated with attention. Because of the large number of tasks observed, their correlations must be interpreted with caution because of the possibility of uncontrolled or hidden variables and of Type I errors. The results of these few studies suggest that there may be a causal relationship between the cognitive deficits in TBI and language comprehension. However, there has been no replication of results to provide converging evidence for this hypothesis. Furthermore, the literature is so spars e that the specific cognitive processes involved have not been identified, nor have the affected linguistic processes been determined. Limitations of Previous Research A major limitation of many of the studies described is the time post injury observations were made. Studies were highly variable in when performance was observed with some as soon as 1 month post injury (Coelho Grela et al., 2005) and others 7 years or more post injury (Yorks ton, Jaffe, Polissar, Liao & Fey 1997). Post injury variability wa s even present within the same study in many cases (e.g. 1 99 months in Coelho Grela et al., 2005; 2 9.79 months in Hinchliffe et al. 1998). Initial

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41 observations within a very short amount of time following brain injury may be confounded by continued phys ical recovery of the brain. It is typical in the aphasia literature, for example, to observe performance no sooner than 6 months to a year following stroke, and it is not entirely clear why the same standards have not been observed in the literature regard ing TBI and language. Aphasia research more often includes treatment studies which track improvement over time, and therefore, it is more necessary to limit the impact of the potential spontaneous recovery which happens during the first six to twelve month s It is an empirical question whether performance at a single point in time at the acute stage of recovery predicts long term functioning of language following brain injury. Brain swelling and other physiological factors may obscure likely outcomes for an y given patient. Controlling for time post injury is therefore important. The typical standard of post injury time in the reviewed studies of TBI is to wait until post traumatic amnesia is no longer evident. However, this standard does not account for the impact of continued confusion and disorientation that can persist during the recovery period and longer for some TBI survivors. In fact, in some studies certain findings were explicitly argued to be based on possible confusion and disorientation (Coelho G rela et al., 2005). In fact, Ellis and Peach (2009) intended to identify syntactic deficits in the acute confusional stage. At the very least, observations made at one month post injury are not comparable between subjects to observations made at one or mor e years. One aspect of language at least, discourse production, has been observed to be disrupted many years after initial injury (Coelho, 2007; Dennis & Barnes, 1990), but whether other deficits persist as well is unknown. Thus, there is a critical need f or

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42 more research delineating the chronic language impairments affecting individuals with TBI. Another non trivial limitation in the TBI language impairment literature is that the vast majority of language research in TBI has addressed discourse level imp airments. The nature of TBI is that brain damage and resulting deficits are likely to vary widely. One of the few studies discussed above that performed any significant testing of basic language functions (Hinchliffe et al., 1998) did find group difference s on a number of basic language measures including: naming, oral expression, reading and listening comprehension, ambiguous sentence comprehension, and many others. Further, these language functions may affect discourse in both direct ways (e.g. failure to comprehend) and unexpected ways (e.g. compensatory strategies as noted by Friedland and Miller, 1996). The limitations of the TBI literature are generally based on problems associated with the heterogeneity of the TBI population Etiologies vary widely with people suffering head injuries from car accidents, falls, blunt assault trauma and other causes. Injury location varies widely, often in multiple locations and is not always readily assessable with a clinical MRI or CT scan. Diffuse injuries, for exam ple, require extremely detailed scanning that is likely only able to pick up a fraction of the damage. Further, TBI survivors can be difficult to recruit if they are no longer in rehabilitation because a majority of TBI survivors have returned to work or s chool and simply may not have the time to donate to a study even with compensation. These factors and others are difficult to control but are probably part of cognitive and linguistic recovery in this population.

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43 There are tremendous gaps in the research of language functioning following a TBI. Basic language functioning needs to be described in more detail with more basic information needed especially about language comprehension. Comprehension is arguably a more integral skill to returning to work and sc hool, but it has received relatively less focus in the TBI literature. Reading comprehension is especially important in returning to school and has received even less attention in the literature than listening comprehension, although the psycholinguistic l iterature offers a range of established techniques particularly suited for assessing reading comprehension. Studies using modern techniques for examining language comprehension, especially reading comprehension, could inform a range of evidenced based inte rventions for this population, once the linguistic deficits and their relationships with cognitive deficits are documented. The current study proposes to begin to fill the large gap in the TBI reading comprehension literature by exploring the nature of rea ding comprehension and cognition in this population using behavioral measures and EEG.

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44 CHAPTER 3 EVENT RELATED POTENTIALS A ND LANGUAGE PROCESSI NG One difficulty with examining language processing in a population such as traumatic brain injury ( TBI ) is that the behavioral assessments available may not capture the sometimes subtle language impairments that may be present due to concomitant cognitive impairments. Cognition is an integral component of complex language use; thus, the identification of langua ge specific processing, apart from cognition, is exceedingly difficult, even in populations without language impairments. Further, deficits specific to task performance (e.g., remembering which button means or even understanding task requirements ) may mask better language comprehension than is demonstrated by answers to comprehension or grammaticality questions. Electroencephalography (EEG) has the potential to provide a source of data more sensitive to language processing due to its high temporal res olution and independence from task performance. Event related potentials (ERPs) reflect changes in neural activity related to a specific internal or external stimulus or event as measured using EEG. Importantly, no response from the participant is necessar y to determine whether processing is occurring. The primary components of interest for the purposes of describing language processing in TBI for this study are the N400 and P600 which are used as indices of semantic and syntactic processing respectively. The use of ERPs to describe language processing deficits has been established by aphasia research (e.g., Angrilli, Elbert, Cusumano, Stegagno & Rockstroh, 2003; Hagoort, Brown & Swaab, 1996; Swaab, Brown & Hagoort, 1997). It is accepted to use l anguage rel ated components to more fully describe the nature of the language deficits associated with

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45 aphasia a group with known language problems (Dobel et al., 2001). The difference in this study is that it is hoped that ERPs may serve as a marker of language proc essing differences in a group with less obvious or accepted language impairments. ERP Components ERP components are features of an EEG that are averaged and time locked to specific stimuli (Groppe, 2007). It is possible in some cases that a relationship be tween an ERP component and a predictable experimental stimulus is also related to a specific ip between a neural network and stimulus (as is assumed with all neuroimaging techniques), but this may not always be true (for a more thorough discussion, see Kutas and Dale, 1997). It is not a question of localization; the inverse problem makes localizat ion particularly difficult with ERPs (see Fabiani Gratton & Coles, 2000, among others). It is a question of whether any measureable component can truly reflect a single process at a given point in time. In this dissertation, the components to be measured are assumed to be functional. That is, observed components may reflect specific distributed networks of neural generators, but the components themselves will be defined functionally by their measureable polarity, latency and scalp distribution. In either c ase, the N400 and P600 components correspond to s emantic and syntactic processing respectively, but their functional and physiological independence from other cognitive processes has been debated. The LAN is connected to earl y syntactic parsing and also to working memory. These components of interest will be described below.

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46 N400: Semantic Processing The N400 is an index of semantic processing difficulty and has a centro parietal distribution that is slightly asymmetrical towards the right hemisphere (Dunc an et al., 2009; Kutas & Iragui, 1998; Osterhout, McLaughlin & Bersick 1997). It begins approximately 200 300ms after the target stimulus has been presented a nd peaks at around 400ms (Lau, Phillips & Poeppel 2008). One of the most widely studied language related ERPs, it was first described as a response to semantically anomalous words within a written sentence (Kutas & Hillyard, 1980) but has since been found in response to word pairs, isolated words, strings of letters, and even faces or pictures ( Debru ille, Pineda & Renault, 1996; Kutas & Iragui, 1998). The N400 response to a word can be affected by many factors, including the predictability of the word in context (single word, sentence or discourse level context), word frequency, sentence position, and word repetition (Kutas & Iragui, 1998; Osterhout et al., 1997). These factors also influence one another. For example, although the N400 is often reduced in response to later occurring words within a sentence, increased semantic incongruity with context c an reduce or eliminate sentence position ef fects (Osterhout et al., 1997). Individual differences in processing strategies may influence the N400 response and may be particularly important to the current study which examines sentence processing in the het erogeneous population of TBI survivors. For example, a subset of normal participants has been found to have a large N400 response with an atypical frontal distribution to target words in ambiguous sentences, whereas most normal participants show a P600 ins tead (Osterhout et al., 1997). Osterhout and colleagues interpreted this as individual differences in how participants viewed the anomalies. They

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47 unexpected word and others w ere sensitive to the semantic integration of the word. The difference in sensitivity was also argued to relate to individual differences in working memory (WM) capacity. Osterhout and collegues suggested that participants with a higher WM capacity may be m ore sensitive to the syntactic aspects of anomalous words simply because they can hold more of the sentence active at one time. However, the distribution than is typically seen in N400 responses. This different distribution suggests that the abnormal response may be similar to a different component, the left anterior negativities (LANs, described below) frequently reported in response to syntactic anomalies with particular relationship to WM (Fiebach, Schlesewsky & Friederici, 2001; Hahne & Friederici, 1999b). The N400 response to a syntactic event that typically elicits a P600, even taking into account the abnormal scalp distribution, suggests that the distinctiveness of se mantic and syntactic levels of processing may not be as clear as frequently assumed. The N400 has been looked at in a wide variety of populations with language impairments or differences (Duncan et al., 2009), including schizophrenia (Kuperberg, Sitnikova Goff & Holcomb, 2006; Niznikiewicz, Mittal, Nestor & McCarley, 2010 ), aphasia ( Angrilli et al., 2003; Hagoort et al., 1996; Swaab et al. wide vari ety of psychiatric disorders. In a study by Angrilli and colleagues (2003), the N400 was even used to provide evidence for neural reorganization of the language network during recovery from aphasia. To my knowledge, however, it has only been reported in a single case study of TBI, and it was only used as a tool to verify possible

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48 semantic comprehension in a patient who appeared to be in a vegetative state (Connolly, Mate Kole & Joyce, 1999). It would therefore be beneficial to further develop an understandi ng of the range of possible N400 responses in TBI in order to be used more reliably in a clinical context. The research looking at the N400 response in the aphasia literature has been useful in understanding the source of comprehension impairment. In a ser ies of publications, Hagoort and colleagues (1996) and Swaab and colleagues (1997) group of people with aphasia. In both studies, rather than group participants by aphasia type ( them by how well they preformed on a comprehension test. In the earlier study Hagoort et al. ( 1996) found that good comprehenders in the group with aphasia had a similar N400 response to the control group for associative (e.g. bread butter) and semantic (e.g. church villa) word pairs that they heard. However, poor comprehenders had a reduced N400 to both pair types. In the later study Swaab et al. ( 1997) found similar differen ces between good and poor comprehension groups on aurally presented whole sentences. That is, poor comprehenders had a reduction and delay of the N400 effect while good comprehenders had a similar N400 response to the control group. In both studies, the re searchers argued that their results suggested that poor comprehenders were not integrating lexical information into previous context, and, in the sentence study, that they were not integrating lexical information into a higher order semantic representation In effect, the poor comprehenders may have been processing shallowly, in the sense that they were not fully integrating the words they were hearing into a

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49 semantic representation. Further, Hagoort and Swaab and colleagues argued that their results were l anguage specific because they were not related to P300 effects that they also measured. The use of a relatively straightforward analysis to demonstrate impaired semantic integration in aphasia provides a promising standard for using the N400 to demonstrate the strength of semantic processing in TBI survivors. P600: Syntactic Processing A late occurring, positive component, the P600, is an ERP that has been associated with syntactic integration difficulty (Hagoort & Brown, 2000; Kaan et al., 2000) and is c onsidered to index comprehension (Gunter & Friederici, 1999; Hahne & Friederici, 1999a). The P600 typically has a medial centro parietal distribution, and it has a wide possible time window between 5 00 and 1000ms following the presentation of a target word. The P600 appears to be largest in amplitude to tasks involving comprehension of sentences with some sort of grammatical error (Gunter, Wagner, & Friederici, 2003; Munte, Matzke, & Johannes, 1997; M unte, Szentkuti, Wieringa, Matzke, & Johannes, 1997), and it is readily observable during complex and ambiguous sentence comprehension in healthy populations (Ainsworth Darnell, Shulman, & Boland, 1998; Burkhardt, 2007; Featherston, Gross, Munte, & Clahsen 2000; Hagoort, Brown, & Groothusen, 1993; Hagoort & Brown, 2000; Hahne & Friederici, 1999a; Kaan et al., 2000; Novick, Trueswell, January, & Thompson Schill, 2004). A separate line of research has examined the P600 in relationship to WM and general rule based processing in order to identify information processing differenc es in groups with known WM and cognitive deficits: schizophrenia (Kuperberg et al. 2006), obsessive compulsive disorder (Papageorgiou & Rabavilas, 2003), and even multiple sclerosis (Pa pageorgiou et al.,

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50 2007). In the context of WM the P600 is viewed as an index of more general rule based processing ( Papageorgiou et al., 2001 ) That is, the P600 may index any voluntary and synchronized process following the detection of a target. The P600 is widely assumed to be at least specific to the integration of knowledge because it can be observed in response to many types of stimuli (Burkhardt, 2007; Frisch, Kotz, von Cramon, & Friederici, 2003; Osterhout & Hagoort, 1999; Osterhout, McKinnon, Bersick, & Corey, 1 996; Osterhout & Mobley, 1995). A limited integration (Wassenaar, Brown & Hagoort, 2004; Wassenaar & Hagoort, 2007). A study by Wassenaar and colleagues (20 04) tested awareness of subject verb agreement violations P600 effect as the control group or the gr oup with right hemisphere damage. Similarly to the N400 aphasia research discussed in the previous section, Wassenaar and colleagues found that a subgroup of poor comprehenders showed a significantly reduced P600 effect than the control group. They conclud ed that part of the effect could have been related to the fact that there was a clausal boundary between the subject information about number across that boundary. Th e study by Wassenaar and Hagoort sentences that did not match a picture. However, the same patients with a reduced or absent P600 effect were above chance in identifyin g the mismatches. The behavioral responses, however, were much more delayed in the aphasic group than the control

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51 group and group with right hemisphere damage suggesting to the authors that the group compensato ry strategy to answer the questions since the accuracy was better than expected based on the P600 Wassenaar and Hagoort also proposed that the absence of a P600 could suggest shallow syntactic fully integrating the syntax o r, in other words, were relying on a shallower semantic representation of the sentence or picture. They could have completed the task with a strategy that allowed them to identify the anomaly without having to fully process th e sentence. Specifically, they always processing the agreement violations. Shallow processing in the sense of only partia l integration of sentence information was also suggested by the research conc erning the N400 in the studies by Wassenaar and colleagues (2004; Wassenaar & Hagoort, 2007), the participants with aphasia did have a P300 response similar to the control group, which they used to conclude that the P600 effects were related specifically to language. There is a history of debate regarding whether the P600 is specific to language, or whether it may simply reflect the engagement of attention ne cessary to identify an unexpected target, represented by another well studied EEG component, the P300 (Coulson, King, & Kutas, 1998a, 1998b). In order to address this debate, Frisch and colleagues (2003) tested a group of patients with aphasia that either did or did not have basal ganglia damage with two experiments. In the first experiment, participants listened to sentences with grammatically correct or incorrect verbs known to elicit a P600. In the

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52 second experiment, they used an auditory oddball task kn own to elicit a P300. In the oddball task, participants respond to target stimuli that occur irregularly and infrequently in a series of standard stimuli. They found that while both groups of patients demonstrated intact attention effects with a clearly ob servable P300, only the patients without basal ganglia damage had an observable P600. This difference indicates that the P300, representing attention, and the P600, representing syntactic processing or integration can be dissociate d Frisch and colleagues however, did not report any behavioral testing beyond two tests classifying aphasia types. The behavioral correlates of this dissociation and the neural generators of each remain unclear and are probably diverse. Researchers who study the P300 hold that the component has a variety of sources that can vary based on modality (Johnson, 1993). As pointed out by Osterhout and Hagoort (1999), whether or not the P600 and P300 are generated by the same underlying physiological processes may not be the most import ant question What is important is that the P600 can be elicited consistently and distinctly to language stimuli. What the Frisch et al. (2003) study later made clear, though, is that regardless of t hey are dissociable. In their study, they were able to dissociate the auditory P600 is from an auditory based P300 response Another controversy surrounding the P600 is its relationship to agreement violations. The computation of agreement between sentence constituents (e.g. between the subject and the verb) is typically considered to be a syntactic process (Kuperberg, Kreher, Sitnikova, Caplan & Holcomb, 2007; Molinaro, Barber & Carreiras, 2011).

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53 Agreement violations, then, would be expected to elicit a P6 00 and possibly a Left Anterior Negativity (LAN), which is a component described in the next section. However, grammatical agreement has many dimensions: number, animacy requirements, thematic role requirements, and others. In a recent review of 29 publish ed studies Molinaro and colleagues (2011) argued that different ERP components are related to different aspects of agreement processing. Specifically they argued that the LAN is a response to expectancy violations, the early P600 is a response to sentenc e level syntactic integration, and an N400 like effect might be related to morphosyntactic markers that activate representations that are not just syntactic. That is, while agreement processing is intended to integrate the syntactic structure of the messag e and integrate this structure into a higher level representation of the sentence, non syntactic information such as morphological markers, may also be used to achieve the same effect. LAN: Early Syntactic Processing The LAN is elicited by s yntactic ano malies in the 300 to 500ms time window with an anterior distribution over the left hemisphere, which differentiates it from the N400 that has a more centro parietal distribution (Fiebach et al., 2001; Hahne & Friederici, 1999b; Sabisch, Hahne, Glass, von S uchodoletz & Friederici, 2006). The LAN has not received the same level of attention as the N400 and P600, and therefore, the functional process represented by the component is not as thoroughly defined. In contrast to the voluntary syntactic processing at tributed to the P600, the LAN has been attributed to first pass or automatic syntactic parsing (Hahne & Friederici, 1999b) and syntactic WM (Fiebach et al., 2001). Hahne and Friederici (1999b) further distinguish between an early left anterior negativity ( ELAN) between 100 and 300 ms in response to phrase

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54 structure violations, and a slightly late r LAN between 300 and 500 ms in response to agreement violations. The WM LAN, or the sustained LAN, has a similar scalp distribution and also begins at about 300 ms but does not return to baseline like the syntactic or focal LAN does ( Fiebach, Schlesewsky & Friederici, 2002). The ELAN is not a focus of this study because it is a relatively difficult component to elicit and measure, possibly due to the fact that it is a more focal, short lived response rather than large, wide spread, long lasting response like the N 400 and P600 (Pulvermller, Shtyrov & Hauk 2009). Because it is assumed to signal the deployment of syntactic WM t he sustained LAN component falling betwe en 300 and 500 ms may be useful in examining language processing following TBI, a population with frequent WM deficits. Osterhout and colleagues (1997) suggested that the LAN is only found in a certain subset of people and that it actually reflects semant ic processing of syntactic stimuli. That is, they argued that it is the N400 despite its more frontal distribution. Osterhout and colleagues (1997) argued that the LAN may be elicited in response to syntactic stimuli only in a subset of the population that may have different WM abilities. As mentioned before, Osterhout et al. proposed that people with a higher WM capacity may be more sensitive to syntactic aspects of anomalous words, so people with a lower WM capacity may only show a semantic response to sy ntactically anomalous stimuli. Similarly, Fiebach and colleagues (2001) argued that the slow wave or sustained LAN was stronger in those with lower WM capacities. Therefore, regardless of whether it reflects semantic or syntactic processing it seems agree d that the component will vary depending on verbal WM capacity,.

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55 Another perspective is that the LAN is not found across studies because it is only found in response to stimuli or paradigms that violate morphological expectancy rather than simply automati c morpho syntactic processing (Molinaro et al., 2011). Unlike the semantic expectancy violations associated with the N400, the expectancy violations associated with the focal LAN are associated with the expected morphology. The current study is not attempti ng to explicitly test for the LAN, but it is an important component to be aware of in a population with known WM deficits such as individuals with TBI. Particularly i f the P600 is not readily observable in response to syntactic anomalies, it would be wort h examining the data for an earlier syntactically elicited component like the LAN. Dissertation Study The interaction between cognition and language processing is beginning to receive more attention in the literature M ost of the research has been done in individuals without impairments. Examining the relationship between cognition and language in TBI survivors may provide a wide range of information about the relationship because of the highly variable level of impairments in the TBI population This stud y examine d two ERP components, the N400 and P600, in response to sentences with and without grammatical and semantic anomalies. If TBI survivors are processing semantics similarly to adults without a history of TBI, the N400 should not be significantly di fferent between groups in terms of latency, scalp distribution or area under the curve. If semantic anomalies are simply not identified as they occur, either consciously or unconsciously, the N400 may be missing in TBI survivors. Shallow integration of sem antics is a possibility suggested by the aphasia research (Hagoort et al., 1996; Swaab et al., 1997) that would also lead to a

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56 reduced or absent N400. Another possibility is that while participants with TBI may eventually recognize a word as wrong, they ma y be initially more accepting of the misplaced word. In this case, the N400 response in TBI survivors may be delayed and have a less pronounced peak than in control participants. If patients with TBI are processing syntax similarly to adults without TBI, the P600 should not be significantly different in people with TBI than in control participants in terms of latency, scalp distribution or area under the curve. If normal processing is not occurring and syntactic anomalies are not identified as they occur or if syntax is only shallowly processed as suggested by the aphasia research (Wassenaar et al., 2004; Wassenaar & Hagoort, 2007) the P600 may be missing in people with TBI. A likely possibility is that comprehension will be more difficult and slower in T BI, but not absent, resulting in a delayed P600 with a longer latency and greater overall amplitude. The focus here is to simply identify the presence or absence and group characteristics of these ERP components given the e xploratory nature of this study. Confirming that there are electrophysiological differences in our sample will help to validate our findings on the language analyses. Previously published studies do not address how the relationships between language and cognitive processing are related t o behavior and sentence comprehension. This study extends previous studies by employing both electrophysiological methods and behavioral methods to address the relationship between language processing and cognitive processing. Once the components are ident ified in this population, the heterogeneous nature of TBI survivors as a group will allow for the possibility of mapping relationships between specific

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57 aspects of sentence processing and cognition, which would not be possible in a more homogeneous populati on.

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58 CHAPTER 4 SENTENCE COMPREHENSI ON DURING RAPID SERI AL VISUAL PRESENTATI ON: A PILOT STUDY Overview The dissertation study was planned to address sentence comprehension in traumatic brain injury (TBI) survivors, who frequently have cognitive deficits. H owever, we first completed a pilot study with healthy control participants to determine if our methods and stimuli were reasonable to use with an impaired group. In order to more directly parallel sentence comprehension and a particular cognitive ability, the original plan for the study was to look at ambiguity resolution and executive function On the surface, they both require conscious suppression of a stimulus and activation of another stimulus. In the case of ambiguity resolution, the stimuli were pres umed to be internal. That is, a reader would have to suppress an incorrect interpretation of an ambiguous sentence internally and then activate the correct interpretation. To test the correlation between ambiguity resolution and executive function we plan ned to correlate a comprehension task of single ambiguous sentences and separate cognitive tasks. However, because of potential task performance impairments in the TBI group, electroencephalography (EEG) was planned in order to look more closely at sentenc e processing as it occurred rather than simply relying on behavioral data When using data collection methods such as EEG, data must be time locked to stimulus presentation. Presentation of visual sentence stimuli for reading is therefore usually accompli shed using a method called Rapid Visual Serial Presentation (RSVP), originally developed for behavioral testing. In RSVP, words are presented one at a time for a short period (e.g. word visible for 250ms, blank screen for 350ms). Conventional wisdom about using RSVP for examining sentence comprehension maintains that

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59 working memory (WM) probably affects sentence processing (Caplan & Waters, 1999; Miyake, Carpenter & Just 1994; Waters & Caplan, 1996). WM is defined broadly here as the ability to actively st ore information and manipulate it according to the demands of the situation (e.g., Engle, Kane & Tuholski, 1999; Saltho use, 1991; Waters & Caplan, 2005 ). However, no studies to our knowledge have directly compared comprehension using RSVP and whole sentenc e presentation behaviorally and related these finding to WM. RSVP was originally used as a way to behaviorally tax linguistic processing (Forster, 1970; Potter, Kroll & Harris, 1980). These early studies found that RSVP reading was affected by linguistic complexity and that recall for passages presented using RSVP was poor. While performance was attributed to WM demands, WM was not directly tested. Further, it is not clear if RSVP actually interfered with syntactic comprehension. This is problematic becaus e RSVP is frequently used to test theoretical sentence processing questions without many or any cognitive tests (Lee & Newman, 2010) despite the expected relationship. Furthermore, RSVP is increasingly being used in studies to make claims about impaired se ntence processing in groups of people that McCa rley, Nestor & Shenton, 2000), including th is dissertation study with TBI survivors. Thus, the effects of RSVP on sentence co mprehension and the relationship between RSVP performance and cognitive abilities are critical questions for the field and one that was important to address if the method was going to be used with a group of TBI survivors To address these questions using our planned stimuli set prior to using EEG we compared reading comprehension following RSVP and whole sentence

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60 presentation, and tested whether reading comprehension in each related to WM or other cognitive factors in a group of healthy undergraduates Th e following sections describe first, different theories of how ambiguity in a sentence is resolved, second, the relationship between cognition and ambiguous sentence processing in people without neurological impairment and finally the relationship between RSVP and whole sentence processing. Ambiguous Sentence Processing A theory of incremental, syntax first parsing would predict that the parser initially build s a syntactic structure based on the least complex interpretation of words as they are encountered (Frazier & Rayner, 1982; Kimball, 1973; Rayner, Carlson & Frazier, 1983; Rayner & Frazier, 1987). When the minimal attachment parser encounters a word that suggests a different parse, it then reanalyzes the entire sentence. The bottom half of Figure 1 sho ws the only correct parse for this sentence with red lines indicating what would be added during reanalysis: [[The florist][sent the invitation]][was nervous]. The principles of minimal attachment and late closure were developed within a modular framework (Frazier & Fodor, 1978). Therefore, non syntactic information, such as plausibility and thematic information would not be presumed to influence parsing until a later interpretation stage. Syntax first parsing is also sometimes called a two stage model to r eflect the incorporation of non syntactic information during the second stage of processing The multiple constraints model was developed as an alternative to the two stage model (Garnsey et al., 1997 ; MacDonald, Pearlmutter & Seidenberg, 1994 ). Rather th an assuming readers approach each word in the same way syntactically, the mul tiple constraints model predicted that multiple sources of information may be used

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61 interactively throughout processing. Several sources of information become available incremental ly as a sentence is processed, but in the multiple constraints model, they are used immediately to guide predictions and processing rather than used during a second revision stage as in the two stage model. For example, c erta in verbs are more frequently u sed with direct objects (e.g. confirmed ) while others tend to be used with embedded clauses more often than direct objects (e.g. figured ). When these biased verbs are used in sentences that go against their most frequent usage, they lead to the garden path effect. It has been found that ambiguous sentences such as (a) take longer to read and respond to than (b) presumably due to this difference in how each verb is typically encountered ( Garnsey et al., 1997 ) (a) The CIA confirmed the rumor should have bee n stopped sooner. (b) The salesman figured the prices would be going up soon. Other factors mentioned that influence or constrain initial interpretation include the frequency a verb occurs in a transitive or intransitive form and even visual or referenti al context (Altmann, 1998). Both the minimal attachment and multiple constraints models were developed to account for a parser that disambiguates alternatives in order to allow the reader to develop the correct interpretation. However, Ferreira (2003) poi nted out that despite this underlying purpose, very few studies of sentence comprehension directly address ed comprehension. Following earlier research suggesting that readers do at least some sort of initial gist like interpretation that may not be correct ed when faced with complex or ambiguous structure (e.g. Late Assignment of Syntax Theory; Townsend & Bever as cited in Ferreira, 2003 ), Ferreira (2003) and Christianson and colleagues (2001) found

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62 that people do not always correct an initially incorrect pa rse. They seem ed to be only interpreting even non ambiguous sentences (Ferreira, 2003) A shallow interpretation is not just limited to syntactic representation, and it has been observed in relationship to lexical ambiguity and even word level errors (Frazier & Rayner, 1990; Frisson & Pickering, 1999). Sanford, Sanford, Molle and Emmott (2006) found that simply using italicization, one of many linguistic attention capturing devices, increased depth of proce ssing. Depth of processing may vary from study to study because it can apparently be affected by a wide variety of linguistic components (Sanford et al., 2006) and because it could be related to how much effort a reader is putting forth ( Ferreira & Bailey, 2004 ). Processing depth is likely to vary between individuals and even dynamically across the course of a task within a single individual ( Gimino, 2002; Iqbal, Zheng & Bailey, 2004 ). Accounting for when and how processing depth varies could partially expl ain some of the variability in ambiguous sentences processing. C ognition and Ambiguous Sentence Comprehension Individual variability in language comprehension could potentially be due to a wide variety of linguistic and non linguistic factors including co gnitive factors such as WM and executive function (EF) The relationship between WM and sentence processing has been explored extensively (e.g., Just & Carpenter, 1992; Kemper & Sumner, 2001; MacDonald & Christiansen, 2002; Waters & Caplan, 1996), but it w as not until fairly recently that studies have begun to examine the role of other cognitive constructs using non linguistic comparison tasks (Grossman, Lee, Morris, Stern & Hurtig, 2002; January, Trueswell & Thompson Schill, 2009 ; Nappa, January, Gleitman &

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63 Trueswell, 2004; Novais Santos, Gee, Shah, Troiani, Work & Grossman, 2007; Novick, Trueswell, January & Thompson Schill, 2004; Novick, Trueswell & Thompson Schill, 2005; Ye & Zhou, 2008). EF in particular, defined generally as intentional or voluntarily controlled neural processes, may explain a large portion of individual variability in performance and variability between studies of ambiguity resolution tasks. WM and Ambiguity The most notable non linguistic explanation of variability has been in the li terature on working memory and language comprehension. Just and Carpenter (1992) identified two phenomena that are not easily incorporated into a theory of language processing without some extra linguistic source of variation. First, when Just and Carpente r (1992) split their participants into two groups based on WM capacity, as measured by reading span, the higher capacity group seemed to use prior disambiguating information to avoid being led down the garden path. People with lower WM capacity did not avo id ambiguity. A second observation by Just and Carpenter was that individuals with a high span actually did worse than low span individuals in certain cases because those with a high span seemed to be maintaining more possible syntactic representations dur ing processing. When the simplest parse did end up being the correct one, high span i ndividuals were actually slower because they were maintaining alternative parses in parallel, in working memory, while low span individuals were not Just and Carpenter ( 1992) argued Syntactic processing appeared, therefore, to be positively or negatively affected by WM capacity, depending on the eventual parse and capacity of the individual. MacDonald and Christiansen (2002) took issue with capacity being the individual

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64 Christiansen instead argued for regularity and individual experience being the contributing factors. Rather than processing exceeding capacity, they claimed that complex sentences were simply more irregular and therefore, some readers had the advantage of greater experience in reading them. The high span participants identified by Just and Carpenter were really just more experienced readers in MacDonald and view. Regularity and individual experience are therefore two more possible sources of variability. The sources of individual variability in sentence processing described by Just and Carpenter (1992) and MacDonald and Christiansen (2002) are largely passiv e resource constraints. One of the resource constraints described by MacDonald and Christiansen (2002), experience, is arguably a more active source of differences than regularity or capacity, but it is not likely to vary considerably within one session (a lthough, Wells, Christiansen, Race, Acheson & MacDonald, 2009 found that four 30 to 60 min training sessions were enough to influence how well non canonical word order was processed). Overall, experience may be influenced by volition, but experience itsel f is not a direct, immediate source of controlled or volitional variability. E F and Ambiguity A source of volitional based variability in language comprehension may be EF. EF is a loosely defined term that has been criticized as being too vague or at least difficult to define (Burgess, 1997) and is sometimes used in exchange with at least two other terms usually used equivalently: supervisory attention (Baddeley, 1986; Miyake, Friedman, Emerson, Witzki & Howerter, 2000; Collette & Van der Linden, 2002) and the central executive (Baddeley, 1986). EF from a neuropsychological perspective generally

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65 processes, such as voluntary planning or effortful control, goal selection, g oal maintenance, cognitive flexibility, inhibition of inappropriate actions and many others (Fernandez Duque & Posner, 2001; Spreen & Strauss, 1998). EFs are often considered to be control processes for lower level functions and some consider EFs only to b e necessary in the case of situations that are novel or requiring adaptation (Miyake et al., 2000; Stuss & Alexander, 2000). Lezak (1982) emphasized that EFs should be separated from cognitive functions, which were defined as quantifiable knowledge, skills a person carries out a behavior or acts towards a goal. Some researchers consider EF to be equivalent to the central executive of working memory and therefore a part o f working memory following Baddeley (1986) while others consider EF to encompass working memory, attention and inhibition (e.g. Miyake et al., 2000; Salthouse, Atkinson & Berish, 2003). EF is a not a unitary construct (Stuss & Alexander, 2000; Alvarez & Emory, 2006) and therefore, it is necessary to look at the subcomponents of EF to relate to the processing of ambiguous sentences. EF components differ from source to source, but they are usually assumed to be located largely in the prefrontal cortex (PFC; Miller & Cohen, 2001). The right hemisphere, basal ganglia, and thalamus are also sometimes thought to be involved with EFs (Lezak, 1982), but most of the research focus has been on the PFC. There is some evidence to suggest that the usual equating of the PFC with EFs is incorrect because there have been cases reported of people with frontal lesions and no EF deficits and of people with EF deficits and no frontal damage (Alvarez &

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66 Emory, 2006). However, EF deficits are difficult to identify due to the mult i factorial nature of EF and the tasks used to test it (Stuss & Alexander, 2000). Therefore, the lack of documented EF deficits in patients with frontal lesions may be due to the lack of a complete enough set of testing materials to identify deficits acros s the range of EF abilities or in an underlying mechanism. There has been little consensus about whether there is a unifying mechanism of EF. The common concept that EF simply refers to controlled rather than automatic processes is not specific enough g iven the wide range of possible levels of control (Stuss & Alexander, 2000). Some researchers do not consider EF to be a unitary construct (Stuss & Alexander, 2000), but others have suggested the possibility that either inhibition (Miyake et al., 2000; Zac ks & Hasher, 1994) or sensory biasing, in the form of cognitive control (Miller & Cohen, 2001), may be what is partially the source of the wide variety of EF variables. Miyake et al. (2000) analyzed the factors underlying a set of tasks thought to test shi fting, updating and inhibition and found that the three factors were distinguishable but still substantially correlated. They argued that the correlation was explained by an underlying basic inhibitory or working memory component. EF may therefore be multi factorial but also have partially shared processing. Only a few of the subcomponents of EF have been looked at directly in relation to language processing: planning, shifting and conflict resolution, and inhibition. These three are discussed below. EF su bcomponents: P lanning Planning is one of the few EF components to be considered in relation to language (Grossman et al., 2002; Nappa et al., 2004; Novais Santos et al., 2007).

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67 sentence processing when needed (Novais Santos et al., 2007). In fact, Novais Santos and colleagues commented that while a parallel approach to ambiguity resolution may seem to require a perhaps unrealistic amount of working memory, the serial approach assumes a much larger contribution from planning and decision making as it only follows the most probable parse. Novais Santos and colleagues do not seem to directly address the possibility of a multiple constraints that would not necessarily put the same strain on working memory (Garnsey et al., 1997), though their point about a possible trade off between working memory and planning is a valid one. They found evidence for processing using ambiguity resolution of reduced relative clauses. Their conclusion about planning was based on increased activation in the dorsolateral prefrontal cortex (dlPFC), previously observed to be recruited for EF tasks like the Stroop (e.g. MacD onald et al., 2000), when the verb was biased towards either a direct object or sentence complement structure and ended up being used with the opposite structure. Previous work has also suggested that the dlPFC may be involved with working memory, however (e.g. Cohen et al., 1997), and so the conclusions are not definitive. Further, they did not include non linguistic tasks in their fMRI study so there was no direct way to compare activation increases across tasks within participants. In a behavioral study Grossman and colleagues (2002) measured EF using a short battery of tasks (including animal naming fluency, Stroop, digit span forward and backward, and Trails B) and sentence comprehension using a word detection procedure that they claimed assessed sens itivity to grammatical agreements as well as a more traditional subject and object gap comprehension task. They found correlations between

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68 their measures of EF and sentence comprehension, though values were not given. They interpreted their results as impl impairments in PD. Specifically relating to planning, they found a difference in performance on Trails B, which they consi dered a measure of planning, between two found a certain percentage of patients performed similarly to control participants and another that performed considerably worse on sentence comprehension measures. The group that did more poorly on Trails B, based on a t test between groups, was also the group that did more poorly on sentence comprehension measures. Grossman and colleagues did include a wide range of tasks, but wit hout correlation values or a factor analysis, it is unclear how each of the observed EF constructs may be related specifically to the sentence comprehension measures, especially in an older population that has been argued to show dedifferentiation between abilities (Baltes, Cornelius, Spiro, Nesselroade & Willis, 1980). A further study by Nappa and colleagues (2004) addressed priming more indirectly as it related to selective attention in speech production. They directed visual attention to scene objects subtly using a 500ms fixation point or subliminally using a 60 80ms cue following fixation. They found that the object that corresponded to the fixation point or subliminal cue location was much more often mentioned first in a sentence than other scene ob jects. This finding suggests that attention can affect the planning of the word order of a message.

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69 Though planning does seem to be related to linguistic processing in some way based on these studies, and certainly must be in the more general sense of mes sage planning, it is far from clear what role the traditional notion of executive planning may play in sentence processing. Strategically planning comprehension has been made an argument against massively parallel processing (Novais Santos et al., 2007), b ut the evidence given here is only preliminary. The fMRI study by Novais Santos and colleagues (2007) based their argument for planning on increased activation in the dlPFC, an area also argued to be used during working memory (Cohen et al., 1997). The ear lier behavioral study by Grossman and colleagues (2002) did not clearly address which aspects of planning were involved as it related to their measures related to their linguistic measures or findings. The more specific study by Nappa and colleagues (2004) only suggested that attention may influence linguistic planning, not how or when planning itself may be carried out. The studies are suggestive, but only address planning in a peripheral way. EF subcomponents: Shifting and c onflict r esolution Planning i s followed by actually carrying out activities (Lezak, 1982), which includes, among many other things, the ability to shift between behaviors and sequences. It has been widely studied in the cognitive literature, but unlike planning, shifting has taken on a wide variety of designations (see Figure 2). While many of the terms are often used interchangeably, they are also sometimes used to refer to performance during certain kinds of task or in certain contexts. Set shifting, for example, may refer specifical ly to when one set or rule is no longer desirable and another is, as in the WCST (Berg, 1948), while flexibility may refer to repeated switching or the ability to

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70 take on new viewpoints in novel contexts (Miyake et al., 2000). Confusingly, flexibility is a lso sometimes defined to literally refer to shifting (Hill, 2004). Shifting in its simplest sense of shifting from one set to another has traditionally been thought to require inhibition of previous items and activation of new items (Alvarez & Emory, 200 6; Collette & Van der Linden, 2002; Stuss & Alexander, 2000). Others, however, think it may be the ability to do something new despite interference, negative priming and distraction (Miyake et al., 2000). The fact that tasks of shifting such as the WCST do not always correlate with inhibitory tasks suggests that shifting is a discrete function. This notion is further supported by the findings of a dissociation between Set shi fting seems particularly well suited to explain ambiguity resolution as, on the surface, both seem to require the suppression of an initial incorrect parse and the shifting to the correct parse. Some researchers have found evidence that we do not fully sup press the initial incorrect parse (Christianson et al., 2001), but this does not necessarily go against the definition of set shifting as doing something despite interference (Miyake et al., 2000). In garden path sentences and comprehension tasks that requ ire more overt control for correct parsing, however, conflict resolution may be a more appropriate term. Conflict resolution has been defined as part of a system that monitors for levels of conflict and then passes that information to control centers in o rder for control processes to respond appropriately (Botvinick, Braver, Barch, Carter & Cohen, 2001). The resolution portion of conflict resolution is in the active seeking of an alternative interpretation or response to the incorrect one (Luo, Niki & Phil ips, 2004). In studies

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71 break mental impasse (Luo et al., 2004). Set shifting by itself is not enough to do so. The conflict resolution system is necessary for the cont rol system to determine just how much control to exert because it is not always correctly estimated prior to a task. The WCST, for example, does not always engage conflict resolution to a large extent because the possible rules are quickly learned and it i s simply necessary to switch between them. A recent review provided by Novick et al. (2005) described the relationship between syntactic parsing and cognitive control with a particular focus on cognitive control in the face of conflict between internal r epresentations. They were concerned with defining the role of the left inferior frontal gyrus (LIFG) and the link between syntactic and non syntactic theories regarding its function. The LIFG has been long thought to be involved with some level of syntacti c processing or syntactic working have found that when damage is limited to LIFG, language deficits are minimal while conflict resolution performance is consistently impai red (Dronkers, Wilkins, Van Valin, Redfern & Jaeger, 2004). Novick et al. (1995) predicted that the LIFG is not involved simply with processing all ambiguous sentences but only those sentences that specifically have multiple conflicting possible parses. Th ey provided a simple explanation of how they predicted cognitive control to interact with syntactic parsing: its initial commitment to the analysis that was strongly pursued up to that

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72 that solution. Then, once this analysis has been suppressed, the parser revises its syntactic characterization of the input to be in accordance with all the available evidence, including less reliable linguistic and nonlinguistic patterns (e.g., referential context). This allows the system to settle into a different analysis that better respects the sentence and situation relevant information. (p. 270) The relationship between cognitive was examined using fMRI by January and colleagues ( 2009 ). They examined activity localization for an ambiguous sentence task and a Stroop task within each participant. The sentence task consisted of participa nts passively viewing scenes while listening to sentences that had a prepositional phrase that could either modify the object or refer to an instrument to carry out the suggested action in the sentence. Participants were instructed to imagine carrying out the actions they heard on the objects in the scene they were viewing. Despite the passive nature of the task, they found that as ambiguity conflict increased and Their results support the id ea of a general cognitive control mechanism being used during syntactic ambiguity resolution. Individual variability in cognitive control relating to syntactic ambiguity resolution was also supported behaviorally by Novick and colleagues (2004). They ask ed syntactic delayed verification task (see Table 1) was used to measure cognitive control. They found that their measures of ambiguity resolution correlated with individual variation on

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73 the delayed verification task and attributed the relationship to a possible shared resource in the frontal system responsible for cognitive control, as was supported by the more recent study by January and colleagues ( 2009 ). Ye and Zhou (2008) offered further support that cognitive control was necessary to ambiguity resolution. They were interested in determining whether the P600 was related specifically to the stage in processing when EF and language interact or rather whether it was related to thematic role reassignment. In order to address their questions, Ye and Zhou compared conflicts of plausibility and syntax in simple active and passive sentences. They also co mpared ERPs between participants grouped by control ability, as measured by performance on the Stroop task. The plausibility of the sentences was manipulated such that the thematic role reassignment view would predict no P600 as there was no animacy violat ions while the cognitive control view would predict a P600 in all cases. They found a P600 in all cases, supporting the cognitive control view. They also found evidence that the P600 may vary based on individual cognitive control abilities. For the low con trol group, they found a single sustained positivity for implausible sentences when compared to plausible sentences. For the high control group, however, they found different responses to plausibility depending on whether the sentences were active or passi ve. Active implausible sentences elicited an anterior negativity, while passive sentences elicited a sustained positivity. They related the anterior negativity seen during active implausible sentences to the anterior negativity observed in other conflict t ype tasks such as Stroop tasks suggesting that higher control participants were actively suppressing alternative parses.

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74 disambiguate sentences differently. Ye and Zhou inte rpreted their findings as suggesting that those with lower control abilities may not suppress alternative parses as well as those with higher abilities. The group difference brings to mind previous findings by Just and Carpenter (1992) that high and low sp an groups performed differently on ambiguity resolution tasks. Just and Carpenter found the seemingly incongruous result that higher span participants seemed to actually have more difficulty, based on gaze durations, than lower span participants on certain sentences because they may be suggested that higher control abilities allow readers to suppress too many alternative parses and they did not find any group difference patterns related to performance on the reading span task as they did for the Stroop task. On the surface, it seems as though working memory and cognitive control abilities could be related. It would therefore be worthwhile to determine first, if higher control per formance was related to higher working memory performance, and second, if longer gaze durations as were seen in relation to higher working memory performance were related to higher control abilities or not. The relationship between working memory and cogni tive control could be directly related to some overall EF ability, or they could dissociate such that those with higher working memory abilities could have lower cognitive control abilities or vice versa. One possibility is that cognitive control is made e asier when fewer alternative parses are able to be maintained in working memory, for example. EF subcomponents : Inhibition Inhibition may be separable from set shifting and conflict resolution (Miyake et al., 2000; Salthouse et al., 2003) and it is used in a variety of ways. Four most

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75 immediately types of inhibition relevant to sentence processing may be resistance to interference, cognitive inhibition, inhibition of prepotent responses and negative priming. Resistance to interference prevents information that is irrelevant to the current focus from entering working memory, and it is distinguished from cognitive inhibition which controlled similarly neurologically (Wilso n & Kipp, 1998). Interference can be measured by decreased efficiency when there are multiple available sources of information that must be ignored or resisted. This is thought to be a passive process, but it is still thought to be related to the frontal l obes. Items that have been cognitively inhibited can be detected through recognition memory, though not through direct recall, unlike items that have been resisted which will not be recognizable. The difference is that actively inhibited items have been en coded in working memory, even if the active inhibition was not overtly recognized. Unintentional inhibition occurs when items have been automatically entered into working memory because of their association with relevant information (Harnishfeger, 1995). However, it is suppressed prior to overt awareness. It is a distinction made to emphasize a possible difference between active, overt or conscious suppression and unconscious suppression, but it may not be easily measured. Wilson and Kipp (1998) pointed ou t that unintentional inhibition may be the type of inhibition used when the irrelevant meanings of polysemous words are suppressed. Inhibition of prepotent responses and negative priming are related. Inhibition of a prepotent response is the inhibition of a positive response to a target that is incorrect or undesired but has been recently the correct target (Jonides, Smith, Marshuetz, Koeppe

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76 & Reuter ve priming is considered to be related to inhibition, but is better understood as the positive response to a target that was recently a distractor. That is, in the reverse of the inhibition of a prepotent response, a negatively primed target requires RSVP and Whole Sentence Presentation A recent study by Lee and Newman (2010) directly compared the effects of RSVP and whole sentence presentation on brain activation using fMRI in an attempt to account for va riation in the complexity effect found in neuroimaging studies. They specifically examined whether activation related to linguistic complexity in BA 44, the hippocampu s was modulated by presentation type. These researchers contrasted activation for conjoined active and object relative sentences using RSVP and whole sentence presentation. They measured accuracy and response times to verification of probe sentences that d escribed an event from the target sentence. Accuracy varied significantly between complexity conditions and presentation conditions, but a significant interaction revealed that there was a larger effect of complexity in the RSVP condition. Response times t o probe sentences only showed a main effect of syntactic complexity with whole and RSVP sentences being slower in the more complex condition. Lee and Newman (2010) concluded that RSVP prevented readers from showing processing benefits in the simpler sente nces, because the serial order processing required by RSVP interfered with either syntactically relevant word order processing or deeper encoding of syntactic and semantic relationships. This conclusion was based on

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77 the observation that syntactic complexit y effects were only observed in BA 44 during whole sentence presentation. Interestingly, hippocampal activation was much larger during whole sentence presentation than during RSVP as well. This suggested that participants were only processing information s hallowly during RSVP, leading to structure. This memory representation was hypothesized t o be necessary for computing the semantic meaning of a sentence, based on the syntactic structure. Unfortunately, Lee and Newman (2010) did not include behavioral cognitive measures. Moreover, their methodology included a 6 second delay between the target and probe sentence, in order to get a clear hemodynamic response to only the target sentence in question, which may have increased WM demands and influenced activation patterns. Further, participants responded with separate hands for true (right finger) a nd false (left finger) sentences. Therefore, their behavioral and neuroimaging results from probe sentences must be interpreted cautiously. Waters and Caplan (1996) also explored the notion that RSVP might tap working memory resources using sentences with sentential complements, reduced relatives, or embedded clauses, all with and without garden path versions. However, their study did not explicitly address the questions of interest here. Specifically, Waters and Caplan compared RSVP and whole sentence proc essing only in older adults (50 80 years old). They also did not explicitly test sentence comprehension, but instead used sentence acceptability judgments. Furthermore, the same sentences were used for RSVP and whole sentence conditions, though they were g iven on separate days. Their methods

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78 also varied somewhat from the norm. In the RSVP condition, they presented words successively for 250ms without a typical blank screen between each word (e.g. Hagoort & Brown, 2000; Osterhout & Holcomb, 1992), which may cause problems of attentional blink, discussed below. Additionally, the screen went blank after the last word of the sentence until the acceptability judgment response was given. Whole sentences, in contrast, were left on the screen until the acceptability judgment was given. The authors acknowledged that these differences in presentation and response type between conditions made a direct comparison of RTs between RSVP and whole sentence presentations impossible. On the other hand, Waters and Caplan did ex amine the effects of working memory by splitting their group into three smaller groups based on reading span performance, which was the only cognitive measure reported. Low WM span participants were significantly worse at deciding the acceptability of sent ences with sentential complement structures. Additionally, the RSVP condition was more difficult than the whole sentence condition overall (i.e., lower accuracy on the acceptability judgments). They argued that differences were likely due to the increased memory load and novelty of the RSVP task, but that there was no differential effect of RSVP on garden path structures and no differential effects of WM on processing. Therefore, while Waters and Caplan did find RSVP was more difficult overall, they also fo und that this difficulty was not exaggerated when the sentence used required more processing, which was quite unexpected. Why might RSVP of sentences be so difficult? RSVP is also used in cognitive research to study temporal properties of information pro cessing, such as target detection and attentional blink (e.g., Broadbent & Broadbent, 1987). In attentional blink

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79 studies, stimuli are briefly presented for identification with no time lag between stimuli, and the faster the targets are presented, the more poorly they are recognized. Attentional blink research has found that when participants are visually attending to items presented sequentially, correctly identifying one stimulus causes poorer identification for subsequent stimuli occurring within the nex t 200 500ms (Broadbent & Broadbent, 1987). The attentional blink effect is attributed to having to eliminate previous items from attention while simultaneously introducing new items, leaving resources limited for higher level processes, such as activation of the meaning of the stimulus word. Thus, the method used by Waters and Caplan (1996), with no lag between sentence words, was more like an attentional blink experiment, than like other sentence processing tasks using RSVP (e. g., Hagoort & Brown, 2000; Ka an et al. 2000; Osterhout & Holcomb, 1992). Pilot Study Predictions We hypothesized that, compared to whole sentence presentation, RSVP presentation would place an added cognitive burden on readers because they received the words one at a time, and combin ed them online in memory, as they appeared. Thus, we predicted that comprehension of sentences would suffer when sentences were presented via RSVP. Furthermore, we also predicted that sentence comprehension accuracy and response times would be related to a variety of cognitive tests tapping working memory and executive function. We were particularly interested in the relationship between ambiguous sentence comprehension and executive function and expected that there would be one, based on previous research (Novick, Trueswell & Thompson Schill, 2005). In order to directly compare whole sentence presentation and RSVP, sentences were presented for the same amount of time in each condition.

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80 Accuracy and response times were collected to comprehension questions th at were presented following every sentence in both conditions. Pilot Study Method s This study examined the relationship between ambiguous and unambiguous language comprehension using RSVP and whole sentence presentation methods. Sentence comprehension wa s compared to WM and executive function in neurologically healthy young adult participants. All participants completed a short neuropsychological battery and two sentence comprehension tasks in one two hour visit. Pilot Study Participants Twenty three hea lthy undergraduate students from the University of Flo rida participated. Participants reported no history of acquired brain disorders, attention deficit hyperactivity disorder, developmental learning or reading disability, uncorrected visual impairment, or impaired mobility of the right hand or finger. The participants with brain injury did not receive compensation. All undergraduate volunteers received course credit for their participation. Pilot Study Neuropsychological Screening The participants complet ed commonly used neuropsychological measures. Digit Span Forward (DSF) (Wechsler, 1997 ), and Digit Span Backward (DSB) tests were used to test WM. The Shipley Vocabulary test (Shipley, 1940), and the North American Adult Reading Test (NART; Nelson, 1982) w ere used to test vocabulary. Trails A and B (Reitan, 1958), and Stroop colors and color words (Stroop, 1935) were used to test executive functions. These commonly used tasks are not described here for the sake of brevity.

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81 A less commonly used working memo ry task, the Operation Span (O Span; Conway et al., 2005) was also completed as a complex WM measure The O Span task has many variations; the version we used required participants to solve simple mathematical problems and to recall letters (Engle, 2005; U nsworth, Heitz, Schrock & Engle, 2005). This version of the O Span consisted of showing a series of letters (between 2 and 5 letters long) presented individually on the computer screen for later recall. Prior to the presentation of each letter, participant s viewed a simple mathematical Finally, a screen was displayed asking the participant to rank the letters in the order they were presented by clicking on them on the c omputer screen in the correct order. If accuracy on the mathematical operations was less than 85% overall, the recall scores would not have been used for that participant. No participants failed to meet this criterion. This accuracy score was shown to the participant throughout the test. Scores on the cognitive tasks are shown in Table 4 1. Pilot Study Sentence Comprehension Tasks Pilot s tudy m aterials Half the sentences in each sentence comprehension were ambiguous and the other half were unambiguous. Al l sentences were between 9 and 11 words long. All sentence stimuli were patterned on the sent ences used in Christianson, Hollingworth, Halliwell and Ferreira (2001) to evaluate whether people completed a partial reanalysis of a garden path sentence when am biguity was encountered in a sentence. The ambiguous sentences were a type of garden path sentence that led the participant to make an incorrect initial interpretation that needed to be revised, as shown in Table 4 2 Comprehension questions were presented following each sentence. The questions

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82 were also similar to those developed by Christianson et al. (2001), which were designed to determine whether or not the sentence was interpreted correctly, even with response and all questions were targeted at the direct object of the first verb in order to test whether the reader correctly resolved the ambiguity Sentences were divided into two lists of 60 items in order to counterbalance the response type between par ticipants Accuracy and RTs for comprehension questions were recorded and analyzed. The sentences were presented randomly for each participant using E Prime (Schneider, Eschman, & Zuccolotto, 2002). Fillers were not used in this pilot study. Task 1: Whole sentence comprehension In the Whole Sentence presentation condition, participants read 60 complete sentences and answered a comprehension question about each. Each trial comprised six events. Participants first saw a 1000ms blank screen with a centered fi xation point. Sentences were presented in their entirety on a computer screen, using a light colored font on a dark colored background, about a half inch above the fixation point. The sentence remained on the screen for 5000ms. The timing of the sentences reflects a normal reading rate for sentences containing 9 11 words (H a goort & Brown, 2000). Following sentence presentation, a blank screen with a centered fixation point was presented for 500ms. Next, a yes/no comprehension question appeared slightly belo w the centered fixation point. After the participant responded using the mouse buttons, a appeared.

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83 Task 2: RSVP sentence comprehension The sequence of events in RSVP presentation was similar to Whole Sentence presentation with the exception of the method of sentence presentation. During RSVP, total presentation time for each sentence was id entical to the timing used in the Whole Sentence Comprehension task (i.e., 5 seconds per sentence), except presentation of sentences was RSVP Each word was presented slightly above the centered fixation point in a light colored font with a dark colored ba ckground on a computer screen. Words were each presented for 300ms followed by a blank screen for 200ms (Kaan et al. 2000). The timing and presentation rate reflect a normal reading rate for young adults (Hagoort & Brown, 2000). Results Ta ble 4 3 shows th e means and standard deviations for the accuracy and RTs for the sentence comprehension tasks. There was a main effect of ambiguity on accuracy using repeated measures ANOVA, F( 1,22)=6.26, p= .020. Responses to comprehension questions were less accurate aft er ambiguous sentences than unambiguous sentences, regardless of presentation type. There was also a main effect of sentence presentation type, F( 1,22)=10.46, p= .004 Responses to comprehension questions were less accurate after RSVP than whole sentence pr esentation. The interaction between ambiguity and presentation ty pe did not reach significance, F( 1,22)=3.740, p= .066 which was likely due to low power. The repeated measures ANOVA results for RTs for correct responses only found again a main effect of a mbiguity, F( 1,22)=8.45, p= .008, with responses to comprehension questions after ambiguous sentences taking longer than those following unambiguous sentences. The main effect of sentence presentation type was not

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84 significant, F( 1,22)=1.658, p= .211, but the interaction between ambiguity and presentation type was, F( 1,22)=8.936, p= .007 Unambiguous sentence comprehension responses did not differ between sentence presentation types, t (44)=1.156, p= .254 but comprehension responses were significantly slower when ambiguous sentences were presented using RSVP than when they were presented as a whole sentence, t (44)=2.472, p= .017 Table 4 4 shows the correlations between the sentence comprehension measures and performance on cognitive tasks. Comprehension accuracy of ambiguous (but not unambiguous) sentences in the Whole Sentence condition correlated with one WM and one executive function measure (TrailsB) In contrast, comprehension accuracy in the RSVP condition correlated only with WM measures. Vocabulary scores predicted RTs but not accuracy in both sentence presentation conditions. RTs for comprehension in the Whole Sentence condition with both sentence types correlated with the executive function tasks (Trails B and Stroop), but only RTs to unambiguous sentenc es in RSVP corr elated with executive function. Pilot Study Discussion and Conclusion Accuracy was found to vary significantly between ambiguity conditions and presentation conditions, but there was also a marginal interaction suggesting that there might be a significant effect of complexity in the RSVP condition with higher power. RTs also showed a significant main effect of ambiguity and a significant interaction between presentation method and ambiguity. These results are consistent with our prediction in some but not all regards. As predicted, responses to comprehension questions following RSVP were less accurate overall than those following Whole Sentence presentation. However, RSVP only significantly affected RTs to questions following

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85 ambiguous senten ces in which responses were slowed significantly compared to Whole Sentence presentation. These findings suggest that RSVP exacerbated the effects of local ambiguity on comprehension as also suggested by Lee and Newman (2010). D isambiguating information (t hat is, the next word ) is not immediately available during RSVP unlike during whole sentence presentation Therefore, understanding sentences presented in RSVP required reliance on WM storage and integration later in the sentence, whereas this information was available much more rapidly during whole sentence presentation. Regarding the second research question that accuracy and RTs would relate to WM and executive function measures, our prediction was not fully supported. Complex WM correlated with accurac y and RTs in RSVP performance, but only with ambiguous sentences RTs. In contrast, timed executive function measures (Trails, Stroop) correlated strongly with whole sentence comprehensi on RTs regardless of ambiguity. C orrelations between RSVP comprehension RTs and executive function measures were limited and only significant for questions following unambiguous sentences. Given that our intention was to test whether people actually fully reanalyze ambiguous sentences, our findings suggest that many do not fu lly reanalyze a significant portion of them, especially during RSVP, despite all participants reporting that the task was subjectively easy. Retaining the unintended meaning of the ambiguous sentence may also contribute to reduced accuracy and increased RT s. Furthermore, it is likely that people with poor WM are less likely to fully reanalyze or fully integrate the correct meaning of these sentences. This is consistent with previous research finding that people with lower WM span process ambiguity, and poss ibly incoming language in

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86 general, differently than those with a higher WM span (Swets, Desmet, Hambrick, & Ferreira, 2007). Our expectation of a strong relationship between ambiguity comprehension and EF performance particularly during RSVP, was not vali dated. These findings clearly illustrate that comprehension of sentences presented using RSVP differs from whole sentence presentation. Comprehension was both less accurate and more sensitive to ambiguity in the RSVP condition. Furthermore, the patterns of correlations with cognitive measures differed for the two presentation methods. We expected comprehension of ambiguous sentences to relate strongly to executive function tasks that required inhibitory control, because it is assumed that ambiguity resoluti on requires inhibition of the initial incorrect interpretation. However, the Stroop task only correlated with sentence comprehension for RTs in the Whole Sentence condition. Therefore, while the current battery of cognitive tasks showed that comprehension in the Whole Sentence condition was highly related to both WM and executive function measures, it was inadequate to explain the pattern of results in RSVP. This finding suggests that there was one or more untested cognitive factor that contributed to compr ehension performance in RSVP. Neuroimaging data supports the notion that an untested cognitive factor may be involved with RSVP comprehension. The effects of s yntactic complexity and associated memory processing as observed via fMRI by Lee and Newman (201 0) suggested that there were much larger effects during the processing of probes following complex sentences than during target sentences. They concluded that people may have been reprocessing the target sentence as well as the probe, generating larger br ain responses. However, this larger effect was attenuated or absent in the RSVP condition,

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87 depending on the brain region, suggesting to Lee and Newman that people may only be processing RSVP sentences shallowly and responding to probe questions using word order information rather than with a deeper understanding of the meaning. This explanation is consistent with our findings of lower accuracy and slower response times to comprehension questions about ambiguous sentences in RSVP relative to Whole Sentence p resentation while there was no difference between RSVP and Whole Sentence conditions for unambiguous sentences These results are also consistent with findings that attentional blink effects can be exaggerated by the complexity of the processing required by stimuli (Van der Burg, Brederoo, Nieuwenstein, Theeuwes & Olivers, 2010). Attentional blink processes suggest that attentional processes may limit comprehension of RSVP sentences, even with a blank screen between stimuli. The blank screen was presented for 200ms; thus, each subsequent word would appear at least partially within the 200 500ms window for attentional blink. A number of limitations were present in this pilot study. First, our cognitive task battery was somewhat limited, as mentioned, and th is has been addressed in ongoing studies. Second, RTs were collected for comprehension probe questions which were presented following the target sentence, as in the Lee and Newman (2010) study. Therefore, our RTs reflected a secondary measure of processing time. However, this is a general problem with RSVP studies that typically present stimuli with fixed timing. We also used a fixed timing of 5 seconds for whole sentences to make the tasks as similar as possible for comparison. Participants reported that t he whole sentences seemed to

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88 stay on the screen for a very long time. Current studies are underway that allow for measurement of individual variability in reading times. This study provides an important look into how RSVP sentence reading may differ from whole sentence reading. RSVP is widely used in sentence processing research. Accuracy, processing time, and cognitive demands all differ bet ween these presentation methods, and these differences would likely be exacerbated in a cognitively impaired populat ion. Therefore, before examining ambiguous sentences using RSVP, our current study took a step back to use only unambiguous sentences with grammatical errors to elicit the P600.

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89 Table 4 1. Scores on Cognitive Tasks Mean SD N NART (max 50) 35.30 6.07 2 3 Shipley (max 40) 32.48 3.78 23 DSF (max 16) 8.30 1.55 23 DSB (max 14) 6.39 1.73 23 O Span (# correct) 40.42 20.55 19 2 Trails A (seconds) 69.52 15.49 21 3 Trails B (seconds) 83.00 21.51 20 3 Stroop interference score 26.88 9.08 17 4 read in 45 seconds number of colors named when word and color are incongruent. 2 3 participants were below the accuracy cutoff score and therefore did not complete the task. 3 Participant errors in completing the task were not corrected by the task admini strator and the time could therefore not be used. 4 The task administrator did that she tested independently instead recording the total time to read the list. Table 4 2. Sentence Types and Examples Sentence Types Examples Ambiguous While the man hunts the rabbit runs into the woods. Unambiguous While the man hunts, the rabbit runs into the woods. Comprehension Question Did the man hunt the rabbit? Tab le 4 3. Scores on Experimental Sentence Tasks Accuracy RT (ms) Presentation Sentence Type Mean SD Mean SD Whole Sentence Unambiguous 0.89 0.12 226 1 802 Ambiguous 0.87 0.12 2150 828 RSVP Unambiguous 0.89 0.09 2532 788 Ambiguous 0.80 0.13 2864 1111

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90 Table 4 4. Correlations between sentence comprehension performance and cognitive measures NART Shipley DSF DSB O Span Trails A Trails B Stroop Accuracy Whole Unambiguous 0.031 0.030 0.107 0.297 0.355 0.075 0.423 0.357 Ambiguous 0.229 0.277 0.290 0.409 .515* 0.399 0.580** 0.279 RSVP Unambiguous 0.319 0.089 0.199 0.234 .479* 0.112 0.335 0.466 Ambiguous 0.129 0.095 0.111 .424* 0.353 0.243 0.356 0.284 RTs Whole Unambiguous 0.499* .578** 0.344 0.272 0.310 0.281 .624** .605* Ambiguous 0.352 .521* 0.224 0.219 0.227 0.388 .663** .601* RSVP Unambiguous 0.241 .572** 0.127 0.199 0.069 0.215 .570** 0.254 Ambiguous 0.357 0.279 0.466 0.284 .605* .601* 0.254 0.115 p< .05, ** p< .01

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91 CHAPTER 5 RESEARCH DESIG N AND METHODS Overview This study examined the relationship between language comprehension, executive function and attention in patients with mild moderate severe (M/M/S) traumatic brain injury ( TBI ) and in neurologically healthy control participants. All participants completed a short neuropsychological battery, the Attention Network Task (ANT) and two sentence comprehension tasks in one three hour visit. One of the sentence comprehension tasks and the ANT were completed while undergoing EEG recording. Par ticipants Five M/M/S TBI patients participated in the study. Table 5 1 shows more details for each participant with a history of brain injury. Three of these were undergraduates at the University of Florida. One was an undergraduate at Santa Fe Community C ollege. One was a member of the surrounding community. Four additional T BI patients were recruited for participation in the study from an existing database of previous volunteers and undergraduates from the University of Florida. These four did not meet st udy criteria due to a history of dyslexia, attention deficit hyperactivity disorder ( ADHD ) or learning disability. An additional 85 to 100 recruiting calls were placed to members of an existing database of previous volunteers with TBI, but approximately 60 of those were no longer available. The remained declined to participate. Twenty six neurologically healthy control participants were also recruited from the Linguistics Speech, Language, and Hearing Sciences (LIN SLHS) database and the local community. Th e participants with brain injury did not receive compensation. All undergraduate volunteers received course credit for their participation. Participants with

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92 TBI were at least six months post injury and no longer exhibiting post traumatic amnesia. TBI seve rity was determined using loss of consciousness duration, post traumatic amnesia duration, and the lowest post resuscitation Glasgow Coma Scale (Teasdale & Jennett, 1974) score as rep orted in medical records, when available. Any participants with a history of other acquired brain disorders (e.g. seizure disorder, stroke), ADHD developmental learning or reading disability, or mobility impairment of the right hand or finger were exclud ed from the study. Participants with uncorrected visual impairments were also excluded. All possible measures were taken to avoid recruiting participants who did not fit study criteria including details in the advertisements, phone call interview, and emai l confirmation of information. Data from five of the healthy control volunteers were excluded from all analyses. One sustained a concussion between the screening interview and the testing date, one reported having had a seizure disorder as a child after te sting started, two tested as having probable chronic depression and anxiety disorders, and testing was not completed with one participant because the computer did not record the EEG properly. Therefore, only the data from 21 control participants were used in the analyses. Table 5 2 shows the demographic information for each group. There were no significant differences between groups on any of the demographic variables using the Mann Whitney test ( p> .05) Cognitive Testing T asks looking at a variety of co gnitive constructs were included in a brief neuropsychological battery Digit Span Forward and Backward ( DSF and DSB from the WAIS III; Wechsler, 1997) were used to test working memory. Shipley Vocabulary (Shipley, 1940) and the North American Adult Readin g Test (Nelson, 1982) were used to test vocabulary. The Stroop test (Golden, 1978) were used to test response inhibition

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93 and conflict resolution. T he Wisconsin Card Sorting Task (Heaton, Chelune, Talley, Kay & Curtiss, 1993) were used to test abstract prob lem solving, executive control and set shifting The Trail Making Test A and B (Trails; Reitan & Wolfson, 1995) were used to test cognitive flexibility and set shifting. The Digit Symbol task (Wechsler, 1997) was used to test processing speed and complex s ustained attention. The Controlled Oral Word Association (COWA; Benton & Hamsher, 1989) was used to test verbal fluency. The Beck Depression Inventory (BDI; Beck, 1996 ) and the State Trait Anxiety Inventory (STAI; Speilberger, Gorusch, Lushene, Vagg, & Jac obs, 1983 ) were used to screen for depression and anxiety symptoms. Table 5 3 shows the tasks from the neuropsychological battery and the constructs they are intended to test. Attention Network Task The ANT was administered to obtain measures of executiv e attention, orienting attention and alerting attention. Stimuli were presented via E Prime (Schneider et al., 2002) using programming freely available for research use (Fan, 2002) First, a fixation cross was visible for a duration that varied between 400 and 1600ms. A warning cue was then presented for 100ms as one of four possible cuing conditions: no cue, center cue, double cue and spatial cue. The target s t imuli consisted of row s of five visually presented horizontal b lack lines, with arrowheads pointing leftward or rightward, against a white background. The target was a leftward or rightward arrowhead at the center and was flanked on either side by two arrows in the same direction (congruent condition), or in the oppos ite direction (incongruent condition), or by lines (neutral condition). The target remained on the screen until the participant made a response, but not for longer than 1700ms. Participants were asked to identify the direction of the centered target

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94 arrow by pressing the left button for the left direction and the right button for the right direction. After the target stimulus disappeared, the fixation cross remained alone on the screen for a period that varied based on the duration of the fixation and RT to the target (3500ms duration of pre stimulus fixation RT). The fixation cross was visible throughout each trial, and participants were asked to focus on the fixation cross throughout the experiment. Different types of attention were assessed by compari ng the various conditions. For example, the alerting response was calculated by subtracting the double cue from the no cue condition, the orienting response by subtracting the spatial cue condition from the central cue condition, and the executive conditio n by subtracting the congruent flanker from the incongruent flanker condition. Experimental Sentence Comprehension Tasks Summary There were two computerized sentence tasks : a grammaticality judgment task was completed during EEG recording with word by word presentation (rapid ser ial visual presentation: RSVP), and a comprehension question task was completed without EEG recording with whole sentence presentation. Both RSVP and whole sentence tasks were necessary to determine whether sentence comprehension wa s affected following TBI. RSVP presentation may alter sentence comprehension performance, as demonstrated in our pilot study, because it may be more cognitively taxing. The RSVP task therefore, was only designed to give limited information about comprehen sion, and was more intended to provide data about language processing via electrophysiological recording.

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95 Materials Each of the sentence comprehension tasks used sentences of the types described in Table 5 4 Sentences were based on those used by Osterhout and Nicol (1999). 225 experimental sentences and 225 filler sentences were developed. 150 of each were be used during EEG recording and 75 without EEG recording The entire set of sentence stimuli is shown in the Appendix. Each experimental sentence was developed with three possible target verbs as shown in Table 5 4 : semantically anomalous, syntactically anomalous and non anomalous target. Semantic anomalies appeared grammatically appropriate to the sentence but violated selection restrictions. That is, were not paired appropriately with Syntactic anomalies always involved a present participle form of the verb following a the alibi The critical words were matched for frequency (using Kucera & Francis, 1967) and letter length. Each filler sentence was developed from 1 verb and 2 nouns that were not used in the experimental sentences and that had a frequency in the same average range as those used in the experimental sentences (using Kucera & Francis, 1967 ). The sentences were all based on the same structure as the example shown in Table 5 4. Three lists were then made so that no single participant saw a sentence more than once. Each sent ence was between 10 and 15 words long (mean=11.5). Each participant saw 50 of each type of sentence with RSVP during EEG recording and 25 of each type of sentence with whole sentence presentation without EEG recording. Presentation of sentences was counter balanced across participants.

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96 All sentences were presented to participants in random order using E Prime (Schneider et al. 2002) followed by task questions. Comprehension questions were designed to determine whether the participant interpreted the sentence correctly. Half of Goodness judgments button if the sent ence just presented was and the right button if it was not. All of the syntactically anomalous sentences were grammatically incorrect (50 total) and two thirds of the fillers were grammatically incorrect (100 total) so that half of the grammaticalit Filler sentences were included in order to avoid learning effects and were developed to be simple active sentences matched in length to the experimental sentences. Sentence Task 1: Whole Sentence Comprehension Partici pants answered a comprehension question following each of 150 t otal sentences (shown in Table 5 4 ). Each trial consisted of six events. After a 1000ms blank screen with a centered fixation point, sentences were presented in their entirety above center on a computer screen in a light colored font with a dark background. Sentences were shown for a minimum of 2000ms. After 2000ms, the participant could press any button to continue to the comprehension question. The comprehension question appeared slightly belo new trial began when the partic ipant pressed a button. Accuracy and reaction time (RT)

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97 were collected from the comprehension questions for further analysis. This portion of the experiment took approximately 30 minutes. Sentence Task 2: RSVP Sentence Comprehension with EEG A second comp rehension task was similar to Task 1 except that stimuli were presented word by word (using rapid seria l visual presentation, or RSVP). It employed 300 novel sentences of the type in Table 5 4 and was administered during EEG recording. After a 1000ms fixat ion, each word was presented in a light font on a dark background at a variable rate depending on the n umber of letters in each word using the following equation: (249.9*[ 16 *number of letters of word] ) 10 ms Each word was followed by 350ms of blank screen. The words were centered on the screen and surrounded by a 2 pixel thick border that was 25% of the size of the screen. A prompt, it was grammatical with the left m below the center point. Three 15 second minimum breaks occurred every 75 sentences. This portion of the experiment took approximately 90 minutes. Figure 5 1 shows an example of the timing of sentence presentation for each sentence task. Participants were encouraged to focus on comprehending the whole sentence, and each sentence was followed by a comprehension question, ha brain waves and that if they needed to blink or yawn, to wait un for further analysis.

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98 EEG Procedures EEG Recording EEG was recorded from 64 scalp sites, using a geodesical sensor net (see Fig 5 2) and Electrical Geodesics, Inc. (EGI; Eugene, Oregon) amplifier system (20,000 gain, nominal bandpass = .10 100 Hz). Electrode placements enabled recording vertical and horizontal eye movements reflecting electro oculographic (EOG) activity. EEG was referenced to Cz and digitized continuously at 250 Hz with a 16 bit analog to digital converter. A right posterior electrode approximately two inches behind the right mastoid served as common gr EEG application took approximately 15 30 minutes depending on how difficult impedances were to reduce. EEG was processed offline using NetStation Waveform Tools. A 30 Hz lowpass finite impulse reponse ( FIR) filter was used with a passband gain of 99.0% ( 0.1 dB), a stopband gain of 1% ( 40.0 dB), and a roll off of 0.29 Hz. Individual files were segmented into 1700ms windows around each target verb (200ms pre target; 1500ms post target) for sentence data. Segments were marked as bad if there were more than 10 bad channels eye blinks, or eye movements. The bad channel threshold was max threshold was max of 20 samples. The eye mo vement threshold was max of 1700ms for sentence data and a moving average of 20 samples. Bad channels were replaced with data interpolated from the remaining channels. The blink slope threshold /ms) was 14.0. Eye channels were then flattened because they could not be used to extract data as they had already been used to correct for eye movement s Individual,

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99 segment averages were calculated from all the segments that were not rejected for each segment category (i.e. syntac tic anomaly, semantic anomaly, nonanomalous control). Source files were handled separately and subjects were not averaged together at this stage. The data was digitally re referenced to an average mastoid reference. Channels marked bad during the artifact correct stage were excluded from the reference. The baseline interval was established as the 200ms preceding each target stimulus. That is, the average of all the samples within the baseline interval was subtracted from every sample in the segment establis hing a new zero voltage value. Files were combined and segments averaged for each group. EEG Analysis Individual participant event related potentials ( ERPs ) were extracted and averaged together in discrete temporal windows that coincided with the onset of each target stimulus. ERP averages were then calculated for each participant separately for nonanomalous control, semantically anomalous and syntactically anomalous stimuli. Waveforms were visually inspected to confirm the time windows and general wavefor m shape. Mean amplitude and peak latency were then calculated for each individual during a specified time window. Time windows used for the ERP components examined were as follows: N400: 300 500ms and P600: 500 900ms. These time windows were determined bas ed on expected latencies for the components and on visual inspection of the grand averaged waveforms. ERP mean amp litudes and latencies were examined with 2 Group (control, TBI) x 3 Stimulus (nonanomalous, semantic anomaly, syntactic anomaly) x 3 Side (lef t mid, right) x 2 Anterior/Posterior repeated measures analyses of variance (ANOVAs). Electrode regions were comprised of the following electrodes: left anterior ( 13, 15, 16,

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100 20 ), left posterior ( 22, 24, 25, 28 ), mid anterior ( 3, 4, 8, 9, 58 ), mid posteri or ( 29, 30, 34, 38, 42 ), right anterior ( 56, 57, 61, 62 ), and right posterior ( 46, 47, 50, 52 ).

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101 Table 5 1. Participants with closed head injury Age Sex Months post injury Etiology Injury details LOC 1 PTA 2 Init i al GCS 3 19 F 44 MVA 4 CT scan revealed brain stem/mid brain contusions and probable diffuse axonal injury; Left skull base fracture; Right frontal ventriculostomy; 1 month outpatient speech therapy according to medical records Yes 3 4 at scene; 7 at ER 24 M 132 Blow to the head with base ball bat at age 13 No hospitalization; Symptoms of concussion: LOC, nauseous, fatigued, dizzy 10 15 min No n/a 55 F 154 MVA Seizures, EEG revealed diffuse abnormalities, CT revealed small right frontal contusion; Approx. 4 years of speech therapy 10 days Yes 4 21 M 24 Fall No hospitalization; symptoms of concussion: fatigue, vomiting, dizzy, light headed, confused for 1 day <1 min Yes n/a 19 F 45 MVA Left frontal craniotomy; 4 months outpatient rehab including speech therapy 5 days Yes Not reported 1 LOC : Loss of consciousness; 2 PTA: Post traumatic amnesia; 3 GCS: Glasgow Coma Score; 4 MVA: Motor vehicle accident

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102 Table 5 2. Demographic averages* Control TBI Age 21.9 27.6 Gender 5 M, 16 F 2 M, 3 F Dominant Hand 17 R, 3 L, 1 mixed 4 R, 0 L, 1 mixed Years of Education Participant 14.2 14.5 Mother 15.9 16.5 Father 16.6 14 Occupation code Participant 11 7.2 Mother 3 4 Father 3.7 1.25 High school GPA 3.6 3.4 College GPA 3.4 3.5 No significant differences between groups p> .05 Table 5 3. Neu ropsychological battery Tasks Constructs Assessed Digit Span Forward (Weschler Memory Scale) Working Memory Digit Span Backward (Weschler Memory Scale) Working Memory Shipley Vocabulary Test Vocabulary North American Adult Reading Test Vocabulary, Estimated premorbid intelligence Stroop Test Response inhibition, Conflict resolution Wisconsin Card Sorting Task (WCST) Executive Control, Set shifting Trail Making Test Set shifting Visual tracking, Processing speed Digit Symbol Task Processing speed, attention Controlled Oral Word Association (COWA) Verbal fluency Beck Depression Inventory (BDI) Depression Screening State Trait Anxiety Inventory (STAI) Anxiety Screening

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103 Table 5 4. Sample sentences a from both sentence tasks Sentence Types Anomalous Semantic 25 Task 1, 50 Task 2 Samples This test of reasoning might hate to discriminate among students. Comprehension Will the test possibly hate to discriminate? Questions b Will the test definitely hate to discriminate? Syntactic 25 Task 1, 50 Task 2 This test of reasoning might failing to discriminate among stud ents. Will the test possibly fail to discriminate? Will the test definitely fail to discriminate? Non anomalous Control 25 Task 1, 50 Task 2 This test of reasoning might fail to discriminate among students. Will the test possibly fail to discriminate? Will the test definitely fail to discriminate? Filler 75 Task 1, 150 Task 2 The cow walked through pasture to eat the green grass near the fence. Did the cow walk through the pasture? Did the cow run through the pasture? a The words in bold in each sen tence represent the target words used in the analysis of ERPs. There are 75 experimental and 75 filler sentences in Task 1 (150 total), and there are 150 experimental and 150 filler sentences in Task 2 (300 total). b Comprehension questions are only used wi th the Whole Sentence Comprehension Task.

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104 Figure 5 1. RSVP sentence presentation timing example Word durations were determined by the number of letters in the word using the equation: ( 249.9*[ 16*nu mber of letters of word] ) 10ms Figure 5 2. Montag e used for EEG analyses, showing the 64 channel arrangement of the geodesic sensor net (EGI; Eugene, Oregon). The 6 regions of interest used in sentence analyses are highlighted

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105 CHAPTER 6 RESULTS Overview The data from 21 adults without traumatic brain injury (TBI) and 5 adults with TBI were analyzed. Behavioral measure results will be reported first followed by electrophysiological results. Anxiety and Depression Screening There were no statistical differences (based on independent samples t tests) betw een groups on the anxiety and depression screening tools. Table 6 1 shows the scores for each group. Neuropsychological Battery There were significant group differences only on the digit span backwards (DSB) task ( p <.05) and the digit symbol task ( p <.05) u sing the Mann Whitney non parametric test. There were no other significant group differences on the cognitive tasks ( p >.05). Table 6 2 shows scores for each group on all of the tasks from the neuropsychological battery. The Wisconsin Card Sorting Task (WCS T) is shown separately in Table 6 3. There were no significant differences between groups on any of the WCST measures Table 6 3 shows six of the raw WCST scores for each group. Further, there were five control participants that performed poorly on the t ask as can be seen in the scatterplot in Figure 6 1. These five participants made incorrect responses at a rate of between 30% and 60%, and only 25% to 60% of their answers indicated that had an understanding of the sorting task.

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106 ANT Alerting, orienting and attentional control scores were calculated based on recommendations from Fan and colleagues (2002). The alerting score was calculated by subtracting the mean RT of the double cue from the mean RT of the no cue conditions. The orienting score was calcul ated by subtracting the mean RT of the spatial cue from the mean RT of the center cue conditions. The attentional control (or conflict) score was calculated by subtracting the mean RT of all congruent flanking conditions from the mean RT of incongruent fla nking conditions. There were no significant differences on any of the calculated scores between groups using the Mann Whitney non parametric test ( p >.05) Table 6 4 shows the scores for the different conditions of the ANT task for each group. Whole Sentenc e Comprehension Accuracy and RTs to comprehension questions following whole sentences were analyzed in separate repeated measures analyses of variances (ANOVAs) using Greenhouse Geisser corrections Any RTs under 200ms were rejected as were the RTs of any inaccurate responses. Table 6 5 shows the means for whole sentence comprehension measures for each group. There were no signi ficant effects of anomaly type, F( 1.57,26.68)=1.38, p= .265 or group, F( 1,17)=.006, p= .394, on accuracy However, t here was a sign ifica nt main effect of anomaly type, F( 1.16,19.64)=5.90, p= .021, but not group, F( 1,17)=.801, p= .383 on RTs. The interaction between anomaly type and group was close but not significant using the Greenhouse Geisser correction, F( 1.16,19.64)=3.880, p= .058 The non corrected data was significant ( p= .030), but the correction was needed because Square=21.006,

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107 p< .001). Post hoc pairwise comparisons of RT using Bonferroni adjustments revealed that pa rticipants were significantly slower to respond to comprehension questions about semantically anomalous sentences than to nonanomalous control sentence RTs ( p< .001) and slower to syntactically anomalous than nonanomalous control sentence RTs ( p= .025). The difference between semantically and syntactically anomalous sentence RTs was not significant ( p= .734). There was a significant main effect of anomaly type on sentence rea ding time F( 1.92,24.94)=9.32, p= .001 There was not a si gnificant main effect of gro up, F( 1,13)=.663, p= .430, or a significant interaction between anomaly type and group, F( 1.92,24.94)=1.12, p= .339. Post hoc pairwise comparisons using Bonferroni correction revealed no significant differences between syntactically and semantically anomalou s sentence reading times combined across groups ( p> .05), but syntactically anomalous sentences were read at a significantly slower rate than nonanomalous control sentences ( p= .014) and semantically anomalous sentences were read at a significantly slower ra te than nonanomalous control sentences ( p= .006). RSVP Sentence Judgment Accuracy and RTs were analyzed in separate repeated measures ANOVAs. Accurate responses only were used in calculating RTs. The 200ms criteria used in the whole sentence analysis was n ot used because the decision about the goodness of the sentence could have been made before the prompt appeared. Table 6 6 shows the means for the RSVP sentence judgment measures for each group. There was a significant main effect of anomaly type on accur acy F( 1.04,24.95)=36.47, p< .001 Nonanomalous and syntactic anomaly accuracy did not significantly differ ( p= .530), but participants were significantly less accurate on semantic

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108 anomali es (both p< .001). There was also a si gnificant main effect of group, F ( 1,24)=6.078, p= .021, on accuracy of RSVP sentence goodness judgments with the TBI group being significantly less accurate ( p= .021). The interaction between anomaly type and group approached but did not reach significance using th e Greenhouse Geisser correc tion, F( 1.04,24.95)=3.68, p= .065. The non corrected F value was significant ( p= .033), but the correction was used because sphericity could not be Square=59.181, p< .001). As can be seen in Table 6 6, the TBI group was disproportionally less accurate than the control group on RSVP semantic anomalies, though the interaction did not reach significance. The from chance based on a one sample t test (mean=.59, t =1.15, p = .264), but the TBI below chance (mean=.22, t= 4.53, p <.01). There was a significant main effect of anomaly type F( 1.13,27.01)=12.50 p= .001, on RTs to goodness judgments of sentences present ed RSVP RTs to semantic anomalies were significantly slower than to syntactic anomalies ( p= .003) and to nonanomalous controls ( p= .019). RTs to syntactic anomalies were significantly faster than to nonanomalous controls ( p= .001). There was no significant e ffect of group, F( 1,24)=.616, p= .440, or significant interaction between anomaly type and group, F( 1.13,27.01 ) =.457, p= .527 Correlations among Sentence Measures Bivariate correlations were calculated for sentence and cognitive task data for the control group. As mentioned, there were significant effects of group on sentence data, but for the TBI group, t here was only one significant correlation among

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109 sentence measures, between whole sentence accuracy on semantic anomalies and RSVP accuracy on no nanomalous control sentences ( r= .976, p< .01 ). Correlations among sentence measures for the control group is shown in t able 6 7. Semantically anomalous RSVP sentence judgment accuracy correlated with all whole sentence RTs and reading times ( r s between .4 50 and .728, p <.05) and with whole sentence comprehension accuracy for only semantic anomalies ( r =.421, p <.05). Further, RSVP sentence judgment accuracy for nonanomalous controls correlated with all whole sentence accuracy, RTs and reading times ( r s betw een .452 and .760, p <.05). However, none of the RSVP sentence judgment accuracy on syntactic anomalies correlated with any of the whole sentence measures. RSVP sentence judgment RTs correlated only slightly less regularly with the whole sentence task acc uracy, RT and reading time measures as shown in Table 6 7 RSVP semantic anomaly and nonanomalous control RTs correlated with whole syntactic anomalous sentence comprehension accuracy ( r = .422, p <.05; r= .698, p< .05). All RSVP sentence judgment RTs correl ated with all whole sentence comprehension RTs ( r s between .414 and .696, p <.05) except between RSVP semantic anomaly judgment RT and whole syntactic comprehension RT ( r =.391 p >.05). All RSVP judgment RTs correlated with all whole sentence self paced read ing times as well ( r s between .458 and .747, p <.05) Correlations between Sentence Measures and Neuropsychological Measures Bivariate correlations were calculated for sentence and cognitive task data using combined groups. The data for the group s was combined because there were only significant differences between groups on the DSB and the accuracy of RSVP sentence judgments. WCST is not shown because there were no significant correlations

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110 between any of the WCST measures and the sentence measure s (all p> .05) despite removal of the five outlying control cases FAS fluency, Animal fluency, and the Stroop interference score correlations are also not shown because they did not significantly correlate with any of the sentence measures (all p> .05). As shown in Table 6 8, there were several significant correlations between accuracy of sentence comprehension and cognitive scores. In the whole sentence presentation task comprehension of semantically anomalous sentences correlated with the Digit Symbol tas k ( r= .540, p< .05), a measure of processing speed. In addition, comprehension of syntactically anomalous sentences correlated with the Digit Symbol task ( r = .425, p <.05) and the Trails Difference score ( r= .473, p< .05), a measure of set shifting or cogniti ve control. Within the RSVP presentation task, sentence goodness judgments nonanomalous sentences correlated with the BDI ( r= .421, p< .05), NART ( r= .398, p< .05), DSF ( r= .457, p< .05), DSB ( r= .546, p< .01) and Digit Symbols tasks ( r= .471, p< .05). In contras t, RSVP sentence goodness judgments for semantically anomalous sentences correlated only with the DSB ( r= .489, p< .05), a measure of working memory, while judgments of syntactically anomalous sentences correlated with the Shipley Vocabulary task ( r= .503, p< .01). A scatterplot for semantically anomalous sentence judgment accuracy versus DSB perf ormance is shown in Figure 6 2. A bimodal distribution of performance was revealed based on judgment accuracy performance. One group that was accurate at a mean of .8 or above and another that was .4 or below. All of the participants with TBI performed in the lower performing group.

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111 Regarding whole sentence comprehension task RTs RTs for semantically anomalous sentences correlated with DSF ( r= .520, p< .05) and DSB ( r= .498, p< .05); people with greater memory spans responded faster. Similarly, RTs for nonanomalous sentences also correlated with DSF ( r= .508, p< .05). RSVP sentence judgment times for syntactically anomalous sentences correlated significantly with the BDI ( r= .598, p< .01), STAI State ( r= .455, p< .05) and NART ( r= .511, p< .01) and for nonanomalous sentences and the Digit Symbols task ( r= .392, p< .05). There were no significant correlations between RSVP judgment times for semantically anomalous sentences and any cognitive measures ( p> .05 ) For whole sentence self paced reading times, there were significant correlations between the BDI and semantically ( r= .641, p< .05), syntactically ( r= .766, p< .05) and nonanomalous ( r= .560, p< .05) sentences ; people with a higher nu mber of self reported depression symptoms took longer to read the sentences Reading time for syntactically anomalous sentences was also significantly correlated with STAI Trait score ( r =.492, p <.05). There were also significant correlations between syntac tically anomalous and nonanomalous control sentence reading times and DSF ( r= .550 and .545, p< .05) and between reading time and the DSB ( r s between .468 and .669, p< .05 ). Reading times for semantically anomalous and nonanomalous controls were significa ntly correlated with the Trails difference score ( r =.410 and .448, p <.05). Table 6 8 shows the results of the correlational analysis. There were also significant correlations between whole sentence comprehension accuracy for syntactically anomalous sentenc es and the Orienting score from the ANT ( r= .529, p< .05) and between RSVP sentence comprehension accuracy for syntactically

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112 anomalous sentences and the Control score from the ANT ( r= .458, p< .05). These scores are not included in Table 6 8. Event Related Potential (ERP) Data Nonanomalous stimuli waveforms contained a n average of 3 2 ( SD 15.2) trials, semantic anomaly stimuli wav eforms contained an average of 3 7 ( SD 17.3) trials, and syntactic anomaly stimuli wav eforms contained an average of 2 8 ( SD 19.1) t rials. A 2 Group x 3 Stimulus ANOVA did not reveal any significant group or stimuli differences in the number of trials per waveform. Target word locked ERP waveforms averaged across participants from the sentence task are shown in Figures 6 3 and 6 4 Vi sual inspection of the grand averaged waveforms confirmed the specified time windows for the N400 and P600 components. Visual inspection also revealed a difference in polarity between the control and TBI groups for certain regions of interest. It is most n oticeable in the Left Posterior region between groups with the syntactic anomaly response having a large positive effect in the control group, but a shorter n egative going response in the TBI group. Mean ERP amplitude and latency data are shown in Tables 6 7 through 6 10. The left posterior negative polarity observed for the syntactic anomalies in the grand averaged TBI waveform in the 500 900ms window held true across the individual waveforms for participant number 602, 604 and 605, but participants 601 a nd 603 showed the more expected pattern of more positive going waveforms for that time window. There was no obvious qualitative association to any differences in TBI severity or behavioral scores.

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113 N400 Component Separate 2 Group x 3 Stimulus x 3 Side (Lef t, Mid, Right) x 2 Anterior/Posterior repeated measures ANOVA s using Huynh Feldt corrections of N400 amplitude and latency revealed only a single significant effect as shown in Table 6 1 3 There was a significant 3 way interaction between side, anterior/p osterior and group effect on amplitude F (2.726,68.155)=3.63, p 2 =.13 Anterior and posterior electrodes were similar for left and mid electrode regions in the control group, but the amplitude was higher for the right posterior electrode than for the r ight anterior electrode. In contrast, the TBI group had higher amplitudes at left and right anterior than posterior regions, and mid anterior and posterior regions were similar. The significant interaction is not depicted in a figure because the range of means was extremely limited (between 4.16E 17 and 5.26E 18). The mean amplitudes and latencies for the N400 measures are shown in Tables 6 9 and 6 10. Figure s 6 5 and 6 6 show the mean amplitude and latency data for the N400 graphically P600 Component A 2 Group x 3 Stimulus x 3 Side (Left, Mid, Right) x 2 Anterior/Posterior repeated measures ANOVA for P600 mean amplitude s summarized in Table 6 14, reveal ed no significant main effects of Group, Stimulus, Side or Anterior/Posterior. However, there were se veral significant interactions. Stimulus interacted signific antly with Side, F (4,100)=2.58, p 2 =.09, but there was also a 3 way interaction between Stimulus, Side and Group F (4,100)=3.07, p 2 =.11: the control group showed larger amplitudes to syntactically anomalous targets across all three sides whereas the TBI group showed lower amp litudes for syntactically anomalous targets only for left regions and for semantically anomalous targets only for right regions, as shown in Figure 6 9

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114 The control group also showed smaller amplitudes for mid regions for nonanomalous and semantically anom alous targets than for the left or right regions. Anterior regions showed a linear trend decreasing amplitude from nonanomalous to semantic to syntactic anomalies, but posterior regions showed a quadratic trend with syntactic anomalies having larger amplit ud e than semantically anomalous and nonanomalous sentences This led to a significant interaction between Stimuli and Anterior/Posterior F (4,100)=10.99, p 2 =.31 and is illustrated in Figure 6 10 Finally, there was a significant interaction between Group, Side and Anterio r/Posterior, F ( 1.981,49.525 )=3.97, p 2 =.14, such that anterior sites generally showed the highest amplitudes on the right side in the control group and in the mid region in the TBI group, and the posterior sites showed the hig hest amplitudes in the left region in both groups as shown in Figure 6 11 Table 6 11 and Figure 6 5 summarize the mean P600 amplitudes. A 2 Group x 3 Stimulus x 3 Side (Left, Mid, Right) x 2 Anterior/Posterior repeated measures ANOVA for P600 mean latenc ies as summarized in Table 6 14, revealed a significant main effect of Group F ( 1,25 )=4.09, p 2 =.14 with the TBI group having a later peak latency and a main effect of Side, F ( 1.35,33.64 )=7.21, p 2 =.22 such that the mid and right side regions had a later peak latency than the left side The TBI ss all three sides, but the control group had a later peak latency on the mid and right side than on the left side, reflected by an interaction that did not quite reach signi ficance between Group and Side, F ( 1.35,33.64 )=3.57, p 2 =.13, that can be see n in Figure 6 1 2 Nonanomalous stimuli had a later latency across anterior than posterior regions while syntactic

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115 anomalies showed the opposite effect, which is reflected in a significant interaction between Stimuli and Anterior/Posterior F ( 1.89,47.18 )=6. 63, p 2 =.21 as shown in Figure 6 13 Table 6 12 and Figure 6 8 summarize the peak P600 latencies.

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116 Table 6 1. Anxiety and Depression Screening Mean Scores by Group Control Group TBI Group Mean Range SD N Mean Range SD N BDI 4.33 0 14 1 3.44 21 4.40 2 10 3.21 5 STAI State 27.38 21 41 5.59 21 24.00 23 26 1.23 5 STAI Trait 33.00 22 41 4.83 21 30.40 26 33 2.70 5 1 We referred three participants to counseling services for depression screening scores over 9. Table 6 2. Neuropsychological Battery Mean Scores by Group Control Group TBI Group Mean SD N Mean SD N NART errors (max 40) 15.86 4.49 21 18.80 3.56 5 Shipley Vocabulary Test (max 40) 33.24 3.46 21 33.00 4.848 5 DSF (max 16) 11.67 2.24 21 11.60 1.342 5 DSB (max 14)* 8.81 2.48 21 6.00 1.23 5 FAS Fluency (COWA) 42.48 7.90 21 43.20 7.50 5 Animals Fluency (COWA) 23.10 5.97 21 23.60 4.39 5 Trails difference time (seconds) 25.22 9.57 21 27.62 9.73 5 Stroop interference score 1 20.05 7.42 21 19.20 12.657 5 Digit Symbol score (seconds)* 118.75 18.33 21 154.57 31.32 5 p< .05; 1 number of colors named when word and color are incongruent. Table 6 3. Wisconsin Card Sorting Task Mean Scores by Group Control Group TBI Group Mean SD N Mean SD N Errors (% o f total responses) 22.36 16.16 21 14.57 .99 5 Perseverative responses (% of total responses) 12.59 10.48 21 7.67 2.68 5 Responses that demonstrated correct conceptualization of the task (% of total responses) 74.62 21.64 21 83.08 2.42 5 Categories compl eted (max 6) 5.33 1.43 21 6.00 .00 5 Number of failures to maintain set .62 .87 21 .60 .89 5 Learning to learn score 1 5.33 10.25 21 1.49 1.12 5 1 Average change in percent errors from 1 category to the next is meant to demonstrate average change in con ceptual efficiency. A more positive score indicates improved efficiency.

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117 Table 6 4 ANT Mean S cores by Group. Control Group TBI Group Mean SD N Mean SD N Alerting 45.22 33.61 20 62.59 27.20 5 Orienting 113.32 40.61 20 129.95 52.46 5 Control 47.14 2 5.33 20 68.61 49.06 5 Table 6 5. Whole Sentence Comprehension Mean Scores by Group. Control Group TBI Group Mean SD N Mean SD N Accuracy Overall .94 .05 21 .92 .08 5 Semantic Anomalies .93 .07 21 .90 .10 5 Syntactic Anomalies .93 .06 21 .90 .09 5 Nonanomalous .95 .04 21 .94 .08 5 RT to Questions (ms)* Overall 2061 70 1 21 2376 727 5 Semantic Anomalies 216 4 694 21 2462 494 5 Syntactic Anomalies 2152 837 21 2792 1171 5 Nonanomalous 2083 647 21 2130 476 5 Self Paced Reading Time (ms)* Ov erall 4263 1726 21 4961 1145 5 Semantic Anomalies 4615 1970 21 521 8 1175 5 Syntactic Anomalies 4650 1875 21 5180 1533 5 Nonanomalous 3763 1449 21 4774 1116 5 p< .05 for main effects using repeated measures ANOVA Table 6 6. RSVP Sentence Judgment Mean Scores by Group. Control Group TBI Group Mean SD N Mean SD N Accuracy* Overall Experimental .83 .28 21 .68 .35 5 Semantic Anomalies .59 .37 21 .22 .14 5 Syntactic Anomalies .94 .06 21 .90 .12 5 Nonanomalous Controls .97 .04 21 .92 .05 5 RT to Sentence Judgment* Overall 792.82 632.75 21 974.74 582.92 5 Semantic Anomalies 1143.16 928.73 21 1397.98 677.62 5 Syntactic Anomalies 542.42 214.95 21 564.71 218.84 5 Nonanomalous Controls 692.88 356.70 21 961.51 498.07 5 p< .05 for main effec ts using repeated measures ANOVAs

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118 Table 6 7. Correlations between RSVP Sentence Judgment Whole Sentence Comprehension Performance and Self Paced Reading Time for Control Participants RSVP Accuracy RSVP RTs Semantic Syntactic Nonanom Semantic Syntact ic Nonanom Whole Sentence Accuracy Semantic 0.421* 0.395 0.795** 0.087 0.291 0.231 Syntactic 0.018 0.227 0.452* 0.422* 0.404 0.698** Nonanom 0.053 0.22 0.485* 0.087 0.235 0.294 Whole Sentence Comprehension Question RTs Semantic .566 0.097 0.605* 0.557* 0.414* 0.681** Syntactic .728 ** 0.179 0.695 ** 0.391 0.449* 0.606 Nonanom .657 0.186 0.760 ** 0.657 0.688 ** 0.696 ** Whole Sentence Reading Time Semantic .535* 0.147 0.685** 0.576* 0.670** 0.611* Syntactic .450* 0.257 0.750* 0.594* 0.747** 0.667** Nonanom .540* 0.253 0.757** 0.458* 0.551* 0.550* RSVP Accuracy Semantic 1 0.15 0.743 ** 0.203 0.209 0.233 Syntactic 0.15 1 0.541* 0.061 0.405 0.078 Nonanom 0.743 ** 0.541* 1 0.233 0.514 0.460 RSVP Judgment RTs Semantic 0.203 0.061 0.233 1 0.692 ** 0.948 ** Syntactic 0.209 0.405 0.514* 0.692 ** 1 0.785 ** Nonanom 0.233 0.078 0.460 0.948 ** 0.785 ** 1 p< .05, p< .01

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119 Table 6 8. Correlations between Sentence Performance and Neuropsychological Battery Perfo rmance BDI STAI State STAI Trait Shipley NART Errors DSF DSB Digit Symbol Trails difference Whole Sentence Accuracy Semantic 0.217 0.106 0.113 0.295 0.175 0.207 0.358 .540* 0.247 Syntactic 0.351 0.027 0.093 0.107 0.06 0.079 0.309 425* .473* Nonanom 0.332 0.112 0.193 0.052 0.231 0.18 0.233 0.232 0.068 Whole Sentence Comprehension Question RTs Semantic 0.343 0.046 0.339 0.045 0.197 .520* .498* 0.304 0.371 Syntactic 0.288 0.056 0.189 0.059 0.3 0.24 0.342 0.306 0.242 Nonanom 0.404 0.086 0.342 0.069 0.28 .508* 0.381 0.159 0.351 Whole Sentence Reading Time Semantic .641* 0.038 0.373 0.337 0.258 0.501* .468* 0.129 .410* Syntactic .766** 0.145 .492* 0.363 0.314 .550* .488* 0.185 0.386 Nonanom .560* 0.08 0 .292 0.378 0.243 .545* .669** 0.364 .448* RSVP Accuracy Semantic 0.163 0.034 0.212 0.035 0.123 0.123 .489* 0.238 0.213 Syntactic 0.221 0.014 0.023 .503** 0.323 0.077 0.199 0.243 0.377 Nonanom .421* 0.012 0.079 0.288 .398* .457* .546 ** .471* 0.284 RSVP Judgment RTs Semantic 0.248 0.3 0.206 0.168 0.049 0.306 0.317 0.121 0.049 Syntactic .598** .455* 0.35 0.277 .511** 0.313 0.184 0.038 0.161 Nonanom 0.304 0.224 0.166 0.084 0.245 0.262 0.293 .392* 0.215 p< .05, p< .01

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120 Tab le 6 9. Mean for the N400 component (300 500ms window) for each stimulus type and region Nonanomalous Semantic Anomaly Syntactic Anomaly Group Region Mean SD Min Max Mean SD Min Max Mean SD Min Max N400 Left Ant 0.51 2.70 3.87 7.21 0.31 1.91 4.97 2.76 0.41 2.80 6.84 6.25 Control Left Post 0.47 1.95 3.14 6.81 0.13 1.58 4.57 3.29 0.72 2.21 2.75 7.79 Mid Ant 0.21 2.80 5.30 7.25 0.37 2.25 7.07 4.17 0.11 3.48 5.07 10.22 Mid Post 0.91 2.16 3.49 6.77 1.04 1.73 5.60 2.97 0.39 2.73 3.80 6.65 Right Ant 0.50 2.63 3.01 6.97 0.52 2.13 4.41 4.29 0.13 3.64 5.42 9.30 Right Post 0.51 1.47 3.09 2.45 0.56 1.72 4.69 3.53 0.31 2.05 3.96 4.81 N400 Left Ant 0.22 1.73 2.58 1.95 0.15 2.69 4.10 2.91 0.99 3.52 5.92 3.44 TBI Left Post 0.57 1.51 1.47 2.34 0.39 1.15 1.88 0.90 0.11 1.22 1.34 1.94 Mid Ant 0.04 2.27 3.61 2.00 1.18 4.28 7.04 3.47 0.81 2.81 4.66 3.09 Mid Post 0.45 1.29 1.08 2.33 0.29 1.24 1.78 1.37 0.49 1.63 1.64 2.20 Right Ant 0.31 1.43 2.47 1.16 1.46 3.36 6.77 1.60 0.70 2.16 3.60 2.48 Right Post 0.61 1.05 0.57 1.82 0.55 1.32 2.18 0.78 0.96 1.16 0.47 2.48 Table 6 10. Peak latencies (ms) for the N400 component (300 500ms window) for each stimulus type and region. Region Nonanomalous Semantic Anomaly Syntactic Anomaly Group Mean SD Min Max Mean SD Min Max Mean SD Min Max N400 Left Ant 417.68 67.35 300.00 496.00 397.50 68.19 301.00 493.00 370.41 43.52 306.00 455.00 Control Left Post 403.73 57.43 319.00 493.00 378.23 50. 25 304.00 490.00 383.45 28.77 333.00 434.00 Mid Ant 404.29 54.95 317.60 496.00 412.73 65.09 301.60 496.00 389.64 47.81 304.80 495.20 Mid Post 400.29 49.33 301.60 471.20 393.96 40.43 318.40 467.20 392.91 33.81 328.00 467.20 Right Ant 395.27 59.87 300. 00 494.00 416.55 54.83 300.00 496.00 393.36 41.37 305.00 451.00 Right Post 404.00 42.01 317.00 484.00 409.77 34.55 358.00 459.00 409.23 37.55 339.00 491.00 N400 Left Ant 368.40 21.49 337.00 395.00 388.20 34.75 330.00 417.00 383.40 26.01 343.00 404.00 TBI Left Post 390.20 16.89 372.00 410.00 394.60 7.99 384.00 405.00 390.40 48.58 304.00 419.00 Mid Ant 386.88 56.02 318.40 449.60 395.68 44.10 317.60 424.00 408.00 19.17 378.40 429.60 Mid Post 413.12 42.16 360.80 455.20 419.52 24.93 395.20 459.20 375.68 24.59 350.40 408.00 Right Ant 399.40 46.75 347.00 441.00 405.40 41.11 351.00 459.00 381.60 31.97 328.00 405.00 Right Post 407.80 58.53 334.00 458.00 423.80 19.55 400.00 446.00 398.00 49.87 331.00 448.00

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121 Table 6 11 for the P600 component (500 900ms window) for each stimulus type and region. Nonanomalous Semantic Anomaly Syntactic Anomaly Group Region Mean SD Min Max Mean SD Min Max Mean SD Min Max P600 Left Ant 0.78 2.45 3.79 6.62 0.57 1.88 3.07 3.91 0.62 3.25 5.73 10.56 Control Left Post 0.67 1.82 2.56 6.41 0.50 1.40 2.49 3.91 1.65 2.47 1.67 10.82 Mid Ant 0.54 2.19 2.96 7.42 0.44 1.92 3.77 3.43 0.86 3.59 4.49 13.79 Mid Post 0.03 1.97 2.94 7.14 0.09 1.58 3.15 2.85 1.86 2.55 1.34 10.51 Right Ant 1.23 2.26 2.10 7.33 1.23 1.89 3.54 5.24 1.23 3.74 5.79 13.22 Right Post 0.12 1.45 2.85 2.92 0.35 1.59 2.71 3.75 0.98 2.09 2.31 6.51 P600 Left Ant 1.64 2.15 0.57 5.08 1.63 0.96 0.41 2.88 0.10 1.99 2.28 2.65 TBI Left Post 1.03 1.01 0.50 2.12 0.53 1.32 1 .43 2.05 1.04 1.29 0.10 3.23 Mid Ant 1.54 2.41 2.14 4.53 1.33 1.38 0.82 2.63 0.71 1.71 0.81 3.65 Mid Post 1.28 1.16 0.24 2.97 0.83 1.28 1.15 2.13 2.37 2.27 1.38 4.73 Right Ant 1.26 2.09 1.45 4.34 0.31 0.83 0.46 1.36 0.76 1.22 0.45 2.82 Ri ght Post 1.23 1.62 0.46 3.66 0.23 1.00 1.08 1.46 2.19 2.00 1.02 3.99 Table 6 12. Peak latencies (ms) for the P600 component (500 900ms window) from the TBI group for each stimulus type and region Nonanomalous Semantic Anomaly Syntactic Anomaly Group Region Mean SD Min Max Mean SD Min Max Mean SD Min Max P600 Left Ant 664.95 117.28 518.00 874.00 660.82 126.56 512.00 882.00 633.68 94.21 508.00 817.00 Control Left Post 632.59 87.70 539.00 875.00 660.95 104.36 542.00 894.00 679.77 76.00 554.00 84 1.00 Mid Ant 719.16 132.78 550.40 886.40 673.67 126.43 508.00 888.00 668.55 114.41 513.60 896.00 Mid Post 736.69 127.13 536.80 896.00 703.96 126.31 505.60 889.60 788.65 55.00 695.20 885.60 Right Ant 738.55 118.98 559.00 880.00 710.05 128.00 538.00 89 4.00 748.23 94.33 561.00 874.00 Right Post 737.95 118.99 559.00 884.00 719.55 116.46 568.00 896.00 799.45 68.33 632.00 887.00 P600 Left Ant 858.80 21.65 835.00 894.00 753.00 139.05 591.00 886.00 697.00 124.46 546.00 882.00 TBI Left Post 737.60 67.88 6 64.00 835.00 765.60 96.19 619.00 884.00 730.00 93.09 620.00 856.00 Mid Ant 825.76 92.52 664.80 896.00 784.00 123.22 587.20 874.40 749.92 162.41 564.00 889.60 Mid Post 801.12 86.48 667.20 893.60 797.12 99.80 628.80 893.60 765.28 82.43 632.80 848.00 Ri ght Ant 823.40 96.59 654.00 888.00 785.80 142.80 542.00 887.00 733.60 115.52 586.00 842.00 Right Post 742.80 145.98 508.00 882.00 765.60 158.29 502.00 891.00 757.00 140.81 508.00 843.00

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122 Table 6 13. Summary of the 2 Group x 3 Stimulus x 3 Side x 2 Ante rior/Posterior repeated measures ANOVAs performed on the N400 mean amplitude and latency data. Amplitude Latency F p 2 F p 2 Group 0.04 0.84 0.00 0.05 0.83 0.00 Stimulus 0.73 0.49 0.03 0.98 0.38 0.04 Side 2.26 0.12 0.08 2.18 0.14 0.08 AntPos t 0.21 0.65 0.01 0.24 0.63 0.01 Group x Stim 0.40 0.67 0.02 0.24 0.79 0.01 Group x Side 1.49 0.24 0.06 0.11 0.90 0.00 Group x AntPost 3.34 0.08 0.12 0.61 0.44 0.02 Stimuli x Side 0.84 0.50 0.00 0.56 0.63 0.02 Stimuli x Side x Group 1.83 0.13 0.07 1.56 0.21 0.06 Stimuli x AntPost 1.10 0.34 0.04 0.13 0.83 0.01 Stimuli x AntPost x Group 0.09 0.91 0.00 1.43 0.25 0.05 Side x AntPost 0.01 0.99 0.00 0.92 0.41 0.04 Side x AntPost x Group 3.63 0.03* 0.13 0.20 0.82 0.01 Stimuli x Side x AntPost 0.57 0.69 0. 02 1.43 0.23 0.05 Stimlui x Side x AntPost x Group 0.25 0.91 0.01 1.21 0.31 0.05 *Significant Table 6 14. Summary of the 2 Group x 3 Stimulus x 3 Side x 2 Anterior/Posterior repeated measures ANOVAs performed on the P600 mean amplitude and latency data Amplitude Latency F p 2 F p 2 Group 0.20 0.66 0.01 4.09 0.05* 0.14 Stimulus 0.71 0.50 0.03 0.57 0.35 0.02 Side 0.06 0.95 0.00 7.21 0.01* 0.22 AntPost 0.00 0.99 0.00 0.14 0.71 0.01 Group x Stim 0.36 0.70 0.01 1.59 0.22 0.06 Group X Side 0.97 0.39 0.04 3.57 0.06 0.13 Gro up x AntPost 0.32 0.58 0.01 0.14 0.71 0.01 Stimuli x Side 2.58 0.04* 0.09 1.03 0.39 0.04 Stimuli x Side x Group 3.07 0.02* 0.11 0.71 0.57 0.03 Stimuli x AntPost 10.99 0.00* 0.31 6.63 0.00* 0.21 Stimuli x AntPost x Group 0.67 0.51 0.03 0.75 0.47 0.03 S ide x AntPost 0.47 0.63 0.02 1.75 0.18 0.07 Side x AntPost x Group 3.97 0.03* 0.14 0.16 0.85 0.01 Stimuli x Side x AntPost 1.02 0.40 0.04 0.82 0.52 0.03 Stimlui x Side x AntPost x Group 0.07 0.99 0.00 1.17 0.33 0.05 *Significant

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123 Figure 6 1. Scatter plot of error and conceptual response percentages on the WCS T for control and TBI groups to demonstrate the large number of outliers in the control group.

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124 Figure 6 2. Scatterplot of RSVP Semantic Anomaly Accuracy and Digit Sp an Backwards performance for control and TBI groups to demonstrate the split in performance on RSVP Semantic Anomaly Accuracy. Group Control TBI

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125 Figure 6 3 Grand averaged nonanomalous, semantic anomaly, and syntactic anomaly ERPs from each electrode region examined for the control group. Microvolts on the y axis, milliseconds on the x axis. 0ms marks the onset of the target word after a 200ms baseline. 1100ms after the target onset is shown in each region. Note that positive polarity is up.

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126 Figure 6 4 Grand averaged nonanomalous, semantic anomaly, and syntactic anomaly ERPs from each electrode region examined for the TBI group. Microvolts on the y axis, milliseconds on the x axis. 0ms marks the onset of the target word after a 200ms baseline. 1100ms after the target onset is shown in each region. Note that positive polarity is up.

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127 Figure 6 5 M ean amplitudes for the N400 component. Error bars reflect the standard error of the mean.

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128 Figure 6 6 Peak latencies f or the N400 component. Error bars reflect the standard error of the mean.

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129 Figure 6 7 M ean amplitudes for the P600 component. Error bars reflect the standard error of the mean.

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130 Figure 6 8 Peak la tencies for the P600 component. Error bars reflect the standard error of the mean.

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131 Fig ure 6 9 P600 m ean amplitudes shown separately for each group to show the Group x S timuli x Side significant interaction ( p = .0 2 )

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132 Figure 6 10 Mean amplitudes combined across groups for the P600 component to show the S timuli x Anterior/Posterior significant interaction ( p< .001 )

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133 Figure 6 1 1 P600 mean amplitudes shown separately for each group to show the Group x Anterior/Posterior x Side significant intera ction ( p=. 03).

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134 Figure 6 1 2 P600 peak latencies showing the Group x Side interaction ( p=. 06). Figure 6 1 3 P600 peak latencies showing the Stimuli x Anterior/Posterior interaction ( p< .01)

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135 CHAPTER 7 DISCUSSION Reading Comprehension Performance Thi s experiment examined the relationship between reading and cognitive components, such as executive function and speed of processing, in healthy young adults and a small group of traumatic brain injury (TBI) survivors. The first aim of this project was to d etermine whether reading comprehension is impaired in TBI survivors relative to matched controls. As predicted, comprehension performance in TBI survivors was significantly impaired relative to the control group though not in all conditions. Although they were expected, finding significant group differences was surprising given that the TBI group size was extremely small. The TBI group was significantly less accurate on rapid serial visually presented (RSVP) sentence judgments There were also interactions between anomaly type and group on whole sentence comprehension accuracy and RTs that did not quite reach significance. In particular, the TBI group was slower to respond to comprehension questions about syntactically anomalous sentences. Comprehension and Cognition The second aim of this study was to determine whether comprehension was related to cognitive impairments. However, there were only two group differences on cognitive measures: Digit Span Backwards (DSB) and Digit Symbol Substitution However, t here was quite a bit of individual variability on the cognitive tasks within the control group. In fact, the participants with TBI numerically outperformed many of the control participants on several tasks, including the WCST, even though the performance d ifference was not significant. Cognitive impairments were therefore not apparent in our

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1 36 small TBI group; thus, we looked at the relationship of comprehension and cognition in the combined groups. The patterns of correlations between comprehension and cogni tion were not entirely straightforward. Whole sentence comprehension question accuracy for semantically and syntactically anomalous sentences was related only to Digit Symbol Substitution and Trails tasks indicating a relationship between comprehension que stion accuracy following anomalous sentences to processing speed and visual set shifting. Sequence maintenance may also be the underlying related cognitive factor between whole sentence comprehension and the Digit Symbols and Trials tasks. RTs to these sam e questions, however, were related only to Digit Span Forward (DSF) and DSB for semantically anomalous and nonanomalous control sentences. The relationships to working memory, set shifting, sequence maintenance and processing speed measures may be due to t he fact that comprehension questions required both reading of the question and reanalysis of the previously seen sentence. The sentence recall may be fairly verbatim, much like the DSF task to which it correlates. The relationship to working memory, execut ive function and processing speed are in accordance with results from the pilot study described in Chapter 4 and with previous findings linking cognitive control, working memory and language (Frattali et al., 2007; Hinchliffe et al., 1998; Youse & Coelho, 2005). Depression and Comprehension Whole sentence s elf paced reading times for all three types of sentences were strongly related to the Beck Depression Inventory (BDI) and syntactically anomalous reading time was related to the State Trait Anxiety Inven tory (STAI) Trait score. Further, RSVP nonanomalous sentence judgment accuracy was related to the BDI and RSVP

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137 syntactically anomalous sentence judgment RTs were related to the BDI and the STAI State scores. Therefore, depression and anxiety levels interf ered with accuracy in judging sentences in RSVP as well as reading times for whole sentences and response times to judge syntactically anomalous sentences. One explanation of this is that depression likely play s a role in a variety of cognitive impairments including executive function and working memory ( Porter, Gallagher, Thompson & Young, 2001; Rose & Ebmeier, 2006 ) Porter and colleagues found that patients with major depressive disorder who were not on psychotropic medications had significantly impaired cognition, especially for tasks of vigilance, spatial working memory, strategy and verbal fluency. Consistent with other findings ( e .g. Just & Carpenter, 1992; Kemper & Sumner, 2001; MacDonald & Christiansen, 2002; Waters & Caplan, 1996 ), w orking memory w as also linked to sentence comprehension in the current study. However, BDI and working memory measures were not correlated in this study suggesting that they are accounting for different portions of variance in comprehension There have been a limited n umber of studies indicating that language performance or at least language use may be affected by depression, mostly in studies of older adults (e.g. Emery & Breslau, 1989 ; Rud e, Gortner & Pennebaker, 2004). In a study of young adult college students, Rude and colleagues (2004) found differences in language use among those with depression. Specifically, those with depression used who formerly had depression. Emery and Bres lau (1989) found a few significant differences between normal elderly and elderly with depression on auditory complex

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138 sentence comprehension tasks from the Western Aphasia Battery and other tasks of syntactic complexity. A directly relevant study by Ruchs ow, Groen, Spitzer, Hermle, Buchheim and Kiefer (2008) directly examined the relationship between the ELAN, N400, LAN and P600 using RSVP in patients with major depressive disorder The N400 had been examined in relation to depression previously (Deldi n K eller, Casas, Best, Gergen & Miller, 2006) but the relationship between the observed negative semantic bias in people with depression did not appear to affect the N400 component Ruchsow and colleagues also found that their group with depression had a sim ilar N400 component to the control group. In addition, there were no observed group differences for the ELAN or the LAN. However, the group with depression did not show a P600 effect in their study while the control group did. This finding is relevant to o ur study since we found a relationship between comprehension performance on semantic and syntactic anomalies and depression symptoms on a scale meant to screen for depression I plan to look more closely at the relationship between the ERP results and the depression scale in future analys e s. The Ruchsow et al. study collected a wider variety of depression and anxiety measures and included information about medication, but they did not utilize the scores in their analysis Their scores and medication informa tion were used to confirm the presence of a severe depressive disorder. Our findings suggest that depression symptoms may relate even at a much milder severity level, since all of our participants scored in the normal mild range on the BDI. Therefore, m ore detailed assessment to identify and describe symptoms could be used to develop a more complete picture of the relationship between mood disorders and language processing.

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139 Exploring this relationship is important to future studies because the prevalence of depression is quite high in the general population with a lifetime prevalence 16.5% of the US population ( Kessler, Berglund, Demler, Jin & Walters, 2005), 15.6% of undergraduates in a large survey study ( Eisenberg, Gollust, Golberstein & Hefner, 2007) and 42% of brain injury survivors ( Kreutzer, Seel & Gourley, 2001). Depression and mood disorders complicate educational and vocational success, and any reading problems associated with those problems could potentially com pound the difficulties. RSVP Perf ormance and Cognition RSVP sentence judgments and cognition also had several notable relationships. Perhaps most notable is the absence of statistical relationships between almost all cognitive measures and accuracy on semantically or syntactically anomalo us sentences. The Shipley vocabulary task correlated with syntactically anomalous RSVP sentence judgment accuracy and the DSB with semantically anomalous RSVP sentence judgment accuracy, but there were no other significant correlations. It is not immediate ly clear what would be special about the one measure, especially in light of the more limited and generally good individual accuracy range of the RSVP accuracy of syntactically anomalous sentences (>.74 for both groups). Vocabulary is clearly related to la nguage comprehension (Braze, Tabor, Shankweiler & Mencl, 2007), and a higher vocabulary size might free up language processing resources so that syntactic errors are detected. However, there was no correlation between the Shipley and other sentence measure s. Another explanation is that t he Shipley task and the accuracy on RSVP syntactic anomaly judgments were both related to exposure to print (Braze et al., 2007) Vocabulary and knowledge of syntactic structure are likely to be related to this

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140 exposure as d iscussed by MacDonald and Christiansen (2002) and could potentially, explain the relationship to the syntactic condition as opposed to other conditions overall. The accuracy of responses to semantically anomalous RSVP sentences were split between a subgro up that did very poorly (just below chance and lower) and people that did more comparably to the other tasks (at .8 and higher). Accuracy on the RSVP semantically anomalous condition correlated with whole sentence semantically anomalous comprehension, and RSVP accuracy on the semantic condition correlated significantly with comprehension question accuracy and self paced reading time in the whole sentence task across all conditions. RTs to the RSVP semantically anomalous condition were significantly slower compared to other conditions, but there was not a split between subgroups as in accuracy. Neither was there a significant correlation between RTs and accuracy rates in the same RSVP semantically anomalous condition. The RSVP task was always presented first to avoid the task being over learned before the EEG data was collected. The correlations between accuracy in the semantic anomaly condition of the two tasks suggest that the very poor accuracy on the semantically anomalous condition is due to more than si mply misinterpreting task instructions or simply looking for the verbs ending in ing That is, we cannot accept the explanation that the poorer comprehenders were only looking for grammatical errors (despite being explicitly told not to) in the RSVP task because the same group also took longer to read whole sentences and was poor on comprehension questions to the same set of sentences One possibility is that the group who made more errors, which included the TBI group, were overall poorer readers who req uired longer exposure times to the verbs to activate the selectional restrictions of verbs in the semantic

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141 anomaly condition than what was provided in the RSVP t ask. T his possibility does not explain the correlation to the whole sentence task but it may e xplain the much worse performance on the RSVP task. The subgroup that did poorly on the semantically anomalous RSVP sentence judgments may also have been limited by working memory to only processing RSVP sentences shallowly. Shallow processing here refers to not fully integrating the sentence into a higher semantic representation or even a fully developed syntactic representation terminology also used by Wassenaar and Hagoort (2007) when referring to patients with Shallow processing in ind ividuals with lower WM spans is consistent with previous literature (Lee & Newman, 2010; Swets et al., 2007) Additionally, shallow processing in RSVP reading is consistent with the findings of the pilot study described in Chapter 4. Shallow processing m ay have led to the particular problems with the semantically anomalous condition because there was no overt cue that a sentence was incorrect as there was in the syntactically anomalous condition ( ing ). In contrast to the lack of relationships between RS VP anomalous sentence judgment accuracy and cognition, nonanomalous control sentence judgment accuracy correlated with the North American Adult Reading Test (NART), DSF, DSB and Digit Symbol Substitution. As mentioned, the TBI group did significantly worse on the DSB and Digit Symbol, but there were no group differences on the NART or DSF. The nonanomalous sentence judgments may have engaged normal language processing and thus the same cognitive variables needed during normal language processing. In additio n, the necessity of double checking to confirm the absence of errors may have further engaged working memory. This possibility is seemingly disputed by the lack of

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142 correlations between RTs and cognitive measures in the nonanomalous condition (i.e. if peopl to do it?). One possibility is that participants may have made their decision about the goodness of some sentences prior to the prompt appearing, leading to the very fast obs erved RTs (within 1 second) for both groups. Thus, the RSVP RTs may not completely reflect processing time differences between conditions, but rather the signaling of a previously computed decision or their confidence of that decision The N400 and P600 T he third aim of this study was to investigate whether typical electrophysiological markers of sentence processing like the N400 and P600 differ in mean amplitude and latency between groups. Our prediction that there would be group differences in the N400 a nd P600 was partially supported. The only group effect found for the N400 window was in amplitude differences across observed electrode regions, independent of stimulus manipulations. Anterior and posterior electrode regions were similar for left and mid e lectrodes in the control group, but the right posterior region detected a larger amplitude than the right anterior region The TBI group, in contrast, had larger amplitudes at left and right anterior than at posterior regions, and mid anterior and mid post erior regions were similar. The amplitude differences across regions may indicate processing differences between groups, but it is difficult to interpret without other significant group or stimuli differences. The lack of a condition related N400 effect c ould be related to task or to material effects. It is possible that participants only processed shallowly in some way to complete the task at the expense of deep semantic processing leading to both the poor accuracy in the semantically anomal ous condition and the lack of a condition related N400 effect.

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143 There could also have been an effect related to animacy violations, which were present in most, but not all of the sentences we used. In the Osterhout and Nicol (1999) study where the stimuli largely origina ted, a robust N400 effect was found, but their task was slightly different than ours There was a 1450ms interval between the sentence and the prompt (my study did not include a delay interval before the prompt) but participants were asked to accept sente nces that were both semantically and grammatically well formed as in our study. Kuperberg and colleagues (2007) offer an alternate explanation for the lack of a condition related N400 effect in the current study T hey found that animacy violations For breakfast the eggs would eat elicited a P600 with a smaller N400 response and their task also included acceptability judgments that followed the final word of each sentence after 1100ms When the agreement violation in the sentence wa s semantic but not animacy related plant they found an N400 but not a P600 response. The possibility of an effect of animacy on what type of ERP component is elicited is worth further study. A f uture analysis of this dataset will explicitly examine the role of animacy on the N400 and P600 responses. It may be the case that sentences with an animacy violation may have elicited a P600 instead of the intended N400 effect. Another possible explanati on for the lack of an N400 effect could be that participants simply did not notice the semantically anomalous word in the RSVP sentences which would also lead to the lack of a condition related N400 observed here and the errors in judgment in the behaviora l measures. Furthermore, the critical verb from which ERPs were measured, was unfortunately not always the point where the

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144 sentence became anomalous. There would not likely be any observable difference on the measures we collected between a focus on synta ctic anomalies due to the task and a lack of deep processing (or full integration) of semantic information leading to poor semantic anomaly judgment accuracy. Moreover shallow semantic processing could also be linked with the use of RSVP rather than the s timuli as was suggested during the pilot study. That is, word by word processing could make identifying semantic anomalies difficult, consciously (as measured through our judgment task) or unconsciously (as measured by the N400). Shallow processing due to RSVP combined with a task bias to focus on morphological markers of syntax and the use of animacy violations as the main semantic violation in this study could have led to the surprising lack of a condition related N400 effect In support of my original p rediction and in contrast to the findings for the N400, there were significant differences between groups for the P600 window. The TBI group had a later latency across all stimuli not related to condition and visual inspection revealed that there were po larity differences between the groups within that window. This later latency could be related to a general slowing of processing, consistent with the Digit Symbol Substitution group difference, as it was not particularly tied to one type of stimulus. Unexp ectedly, the TBI group had negative deflections rather than positive going deflections as in the control group, al though there was not a significant group difference in amplitude. The left posterior negative polarity observed for syntactic anomalies in the averaged TBI group waveform held true only across individual waveforms for 3 participants with the other two participants showing a pattern more like the normal individual waveforms reflecting the individual variability that was expected

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145 This split was n ot obviously related to severity, etiology or any behavioral measures, including accuracy or reaction times. A split between subgroups is not unexpected, as TBI survivors as a group are a highly heterogenous population to begin with, and the studies lookin (Wassenaar et al., 2004; Wassenaar & Hagoort, 2007). The reason for the large negative going wave in the syntactic anomaly condition in the 500 900ms time window is not clear and could simpl y be an artifact of the extremely small group size. Alternatively, i t could reflect a difference in processing when syntactic anomalies are encountered and it does suggest that these three individuals were sensitive to the ungrammaticality since it is lar gest for the syntactic anomaly condition A similar late negative going component has been found under certain conditions in second language processing (Sabourin & Stowe, 2008). It has been interpreted to reflect the recruitment of working memory resources when it has a frontal distribution, and in the case of non native speakers, the negativity to grammatical errors could actually reflect a positivity for the nonanomalous sentences. Sabourin and Stowe describe this positivity in response to the grammatical condition as reflecting the fact that non native speakers might see a chance of success in processing the sentences. In this study, people with language impairments might show a more positive going wave to the nonanomalous and semantic anomalous sentence types because they are attempting to process those sentences more fully in the absence of a overt syntactic error The scalp distribution in the TBI group is different from frontal distribution observed by Sabourin and Stowe in non native speakers, however but the possibility would be interesting to address in future studies.

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146 Taken together with behavioral performance differences, P600 differences both between groups and within the TBI group suggest that event related potentials (ERPs) are a promising tool for sentence processing impairment identification. The findings raise the possibility of fundamentally different strategies for processing syntax in some people with the possibility that a subset of the TBI group and possibly of the control group is proce ssing sentences shallowly for a variety of reasons such as task demands or mode of presentation Additional studies with larger groups and a wider variety of complex syntactic structures would be necessary to reveal the relationship between observable pro cessing differences and ERP waveforms. Clinical Implications These results have several clinical implications. First, the TBI group did show evidence for language processing differences at the sentence level that could be leading to challenges in school or work settings They had near significantly worse accuracy and significantly slower reading times in the whole sentence task. T hey showed that they may not have been fully integrating semantic information especially in the word by word condition, and they may have been using a compensation strategy to complete the tasks that did not require deep processing or full integration of semantic or syntactic sentence level information. Furthermore, performance was related to processing speed and working memory sugg esting that these skills do need to be supported to support reading, which is current clinical practice ( Coelho et al., 2005; Hinchliffe et al., 1998; McDonald et al., 2000; Turkstra et al., 2005 ). However, o ur results suggest that reading for depth or for semantic integration is a potential clinical target, even at the sentence level, that is not typically addressed even when TBI sur vivors receive language therapy ( Coelho et al., 2005; Turkstra et al., 2005 ). Poor

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147 semantic integration at the sentence level would make accurate comprehension of a passage in a textbook, article or book difficult and slow. The relationship between sentence reading measures and depression also has important clinical implications. Language processing problems may be more producti vely addressed after depression is treated. The possibility of a relationship between language and depression has ethical implications for those who work with people who have depression such as doctors, counselors and pharmacists who should be made aware o f the link. These findings suggest that even a non clinically significant number of depression symptoms may adversely affect language performance and should be addressed. Finally, cognitive fatigue may have differentially affected the performance of the TB I group (Belmont, Agar, Hugeron, Gallais & Azouvi, 2006), and should be addressed in future analyses by examining performance changes over the course of the experiment or splitting testing over more than a single session Fatigue is important to address in future studies because it is not controlled for by other measures such as severity or time since injury, which are unrelated (Belmont et al., 2006). It can be related to a wide variety of factors that would be difficult to control for such as fatigue from coping with attention deficits and slowing, depression or pituitary insufficiency, but fatigue itself could be screened. Limitations There were several weaknesses in this project that should be taken into account for future studies. First and foremost, ou r extremely limited TBI group size prevented a more extensive exploration into the relationship among behavioral and electrophysiological variables and group membership. A larger group would allow for more detailed and powerful analyses and will be necessa ry to make any more generalized conclusions about these data. Despite this limitation, however, group

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148 differences were still found suggesting that the hypothesized group differences in reading may be more powerful than initially suspected. A second limita tion of the sample used in this study was that nearly all of the participants in both groups were undergraduates. The homogeneity of the sample prevents generalization of the results to a more varied group. On the other hand, the sample is entirely appropr iate due to the nature of the task. Reading tasks are one of the particular challenges for student survivors of TBI and one of the groups most in need of further research on the effects of TBI on reading. The number of students surviving concussions is lik ely underreported and therefore an interesting subgroup of the TBI population as a whole. The cognitive tasks used also did not likely fully account for all of the cognitive interactions present with the reading tasks, but that is unsurprising given the ex ploratory nature of the study and the time limitations. The interactions seen between working memory and tasks requiring processing speed provide a starting point for future cognitive batteries. The interaction with simple depression and anxiety screening measures also provide a useful starting point. Undesirable task related influences on sentence processing are also easily addressed in future studies, though difficult to tease apart in the current data. It is unclear in this study whether the task influe nced how the RSVP sentences were read and therefore the N400 response. Part of the strength of using electrophysiological data is that ERPs can be elicited in the absence of a task. A task may exacerbate or mask any observed processing, and it is important to distinguish the possibilities. Between the possible task related effects in this current study and possible task related effects in the

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149 TBI population in general, future studies should consider a task free ERP study to identify and examine sentence pro cessing effects in TBI groups. An ERP study using auditory stimuli is another option to look at sentence processing that has been used in the ERP literature looking at aphasia (Hagoort et al., 1996; Swaab et al., 1997; Waassenaar et al., 2004; Wassenaar & Hagoort, 2007). Conclusion This study confirmed that reading is a complex skill that is strongly tied to cognitive processing. In particular, verbal memory, executive function, processing speed and vocabulary are related to sentence comprehension. Further more, depression and immediate anxiety symptoms may affect sentence reading time and comprehension. The overall goal of this study was to explore the relationship between reading and cognition in TBI. The results provided evidence that reading is a challen ge to TBI survivors, especially in light of the fact that four of the five participants were undergraduates. It also suggested that reading processes and reading impairment vary individually. Further exploration of the relationship between cognition and re ading and especially mood and reading is warranted given the strong relationships found in this study.

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150 APPENDIX A RSVP SENTENCE STIMUL I WITHOUT COMPREHENS ION QUESTIONS RSVP Sentences (nonanomalous/syntactic anomaly/semantic anomaly) A live audience will w itness/witnessing/powder the performance by the new composer. A new computer will work/working/paint for many years if maintained properly. After the pleasant meal, the couple will tip/tipping/light the waiter well. Alison used a hammer to crack/cracking/kiss the small lock open. At the end of the day, the dog always waits/waiting/peaks in the driveway. At the front desk, the receptionist will register/registering/ cope new appointments in the calendar. Betsy went out to the orchard to pick/picking/melt apples for a pie. By the end of the semester, the student will earn/earning/pump a good grade Critics say that the rap songs might tend/tending/learn to lead young people astray. Every day at three, the newspapers should land/landing/dance on the porch out front. For the appetizer, the waitress will recommend/recommending/air the cheese dip. Hopefully the painter will notice/noticing/core the areas that need an extra coat of paint. It was hard to get the infant to smile/smiling/vote for the photographer. Mary knew that the food at the hotel would cost/costing/fight too much. Most physicians believe that the new drugs can prevent/preventing/study many forms of disease. My brother bet that this spider could climb/climbing/type faster than you could. normal otherwise. My mother worried that she would not have time to vacuum/vacuuming/box before the party. Simple vegetable oil is used to fry/frying/plow the vegetables for the soup. So many bugs live in the garden, they must devour/devouring/buy a whole ca bbage every minute. Susan was worried that her kitten would scratch/scratching/lift the young child. The accountant wants to count/counting/bat the expense as part of a donation. The administrator will supervise/supervising/upset the plumber behind the new house.

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151 The army did not ambush/ambushing/read while the soldier was digging the trench. The assistant was told that the alibi would prevent/preventing/consider an indictment. The astronomer thinks he should map/mapping/close the new star system firs t. The astronomer's argument might prove/proving/shout that there are three canals on the moon. The biography will fall/falling/laugh off the shelf if the shelf moves The black widow spider likes to hide/hiding/sigh in dark places. The blue knit hat will warm/warming/warn the boy while he plays outside. The booklet says that the contraceptive will fail/failing/complain if used too sparingly. The boss might study/s tudying/kick the analysis more closely next time. The bus driver did merge/merging/contract correctly on the busy freeway. The busy stepfather plans to visit/visiting/staff every holiday with his wife. The carrots need to boil/boiling/frighten before th e stew is served. The cats will not eat/eating/bake the food that Mary gives them. The children want to play/playing/star with the ball outside in the sunshine. The circus elephants get on their hind legs and stand/standing/chirp, which impresses the au dience. The city workman will fix/fixing/bake the bus that broke down yesterday. The clowns will entertain/entertaining/weigh everyone when the circus is here next month. The colors in the sweater should not fade/fading/walk when the sweater is washed. The courier asked the administrator to sign/signing/golf for the package. The courier will drop/dropping/wipe off the form for her to sign. The cowboy always g ives his horse a chance to drink/drinking/fish from the stream. The cowboy will rescue/rescuing/faint the calf that is stuck in the ravine. The crowd will debate/debating/loan whether the army will advance without warning. The customer will pay/paying/f erry only if he likes the steak. The decorator for the mansion will hang/hanging/roof new artwork in the parlor. The deer might spring/springing/coast away from the water if they sense the danger. The deer will leap/leaping/scheme away if you do not mov e quietly.

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152 codefendant. The dog will beg/begging/grip if you start eating that steak. The dust on the stored furniture will aggravate/aggravating/remedy the allerg ies of the man. The experienced classroom instructor will observe/observing/channel the new students talking. The fancy French clock does not tell/telling/ask the time during power failures. The farmhouse is so old that it scares/scaring/writes the neig hbors. The football player wants to practice/practicing/contact the routine again tonight. The gangster in the car might chase/chasing/nibble the man running down the street. The gas stove will leak/leaking/bar again if it is not fixed properly. The ge neral agreed to discharge/discharging/pen the soldier who had been injured. The girl wanted to hug/hugging/ticket her brother before he got on the bus. The guitarist wanted to present/presenting/carve the new piece for the crowd. The hiker used his last match to start/starting/tie the fire. The house painter will paint/painting/feed the hall a bright color. The kindergarteners knew to glue/gluing/market the shapes to the construction paper. The landlord might collect/colleting/fan rent late from the f amily tomorrow. The lecture by the professor will take/taking/sprout all afternoon to finish. The leftover pizza will mold/molding/drive if it is left out too long. The lever on the basement wall does not shut/shutting/lift off the power supply. The li ttle boy went to kiss/kissing/pity his mother on the cheek. The man in the parked van might honk/honking/echo the horn. The man will prepare/preparing/stable the leftover turkey tomorrow for dinner. The manager will vacuum/vacuuming/salt the storage roo m for the furniture. The mercenaries want to hunt/hunting/praise for the escaped prisoner tomorrow. The minister truly does believe/believing/nurse that everyone will benefit from it. The mother and father do love/loving/institute their daughter very mu ch. The movers did not think that the piano would weigh/weighing/cough as much as it did. The musicians in the booth will rehearse/rehearsing/explode the song before they perform. The musicians will tune/tuning/justify their instruments before the perfo rmance this evening. The nanny will dress/dressing/sink the toddler in warmer clothes if it is snowing. The new brand of toothpaste could help/helping/beg to provide protection against disease.

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153 The new chemical additive may tend/tending/desire to lower the freezing point of water. The new cop needs to pursue/pursuing/pipe the criminal down the busy street. The new crop of corn should feed/feeding/scrape everyone in the state. The new dance routine should entertain/entertaining/rush the bored audience tonight. The new detergent is supposed to polish/polishing/burn the floors with ease. The new fighter plane can fly/flying/walk faster than anyone had expected. The new romance novel should sell/selling/leak in every store this year. The new software package will print/printing/glue very elaborate pictures on nice paper. The new songs will impress/impressing/chance the singer of the band. The new species of orchid will thrive/thriv ing/sing in tropical regions. The new stepfather will have to disclipline/discliplining/lead the toddler for hitting his brother. The new teacher will supervise/supervising/cash the exam for the students. The newly planted grass will grow/growing/swim q uite a bit during the next year. The office manager might budget/budgeting/impact for a department party for the holiday. The old engineer could still invent/inventing/pile new devices to save time. The pacifier we bought in Japan will soothe/soothing/d rop the cranky baby. The parked truck will delay/delaying/respect oncoming traffic in the street. The peregrine falcon chicks always chirp/chirping/staple until the father brings food. The pet cats will soon enjoy/enjoying/describe their evening meal to gether. The platter of cheese will feed/feeding/edge all of the guests. The playful dog will only sit/sitting/drain if given a treat. The plumber said that the leaking water might seep/seeping/speak out from behind the refrigerator. The policeman will catch/catching/brief the slow woman on the corner. The poor author will write/writing/harness a new book for children. The portrait of Uncle Henry does not look/looking/sing like him. The powerful magnet will pull/pulling/learn defective parts from the assembly line. The publisher hoped that the textbook would draw/drawing/hear students with a variety of interests. The puppy seems to like/liking/call/calling to sleep a lot during the day. The quiet nanny might read/reading/mortgage a book to the chi ldren in the park.

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154 The rebel attack will surprise/surprising/pioneer the dictator of the country. The red ants in Arizona will bite/biting/wash you if you are not careful. The repairman thinks that the leaky tub might bother/bothering/ask the tenants do wnstairs. The restaurant critic plans to compliment/complimenting/prejudice the well cooked veal. The roommate will promise/promising/crawl to clean the den for the party. The roses in the corner plot will thrive/thriving/spin in the sun. The scientist will carefully review/reviewing/fork the research article with the professor. The security camera at the bank will now take/taking/trip photographs of everyone. The simulated accident might frighten/frightening/ignore the children enough that they will wear their bike helmets. The stamp collector will buy/buying/spite as many stamps as he can find. The stealthy tiger might attack/attacking/slow the village if it is hungry. s more thoroughly. The tailor will consider/considering/purse different designs for the new suit. The tailor will patch/patching/pot the hole in the jeans for a small fee. The tall runner did slip/slipping/raid on the wet track close to the finish line. The tired assistant will iron/ironing/key the dress for the customer. The tired detective might phone/phoning/value the lawyer about his notes. The tourist could only hope/hoping/sweat to see the monument before leaving. The tree in the backyard can not sprout/sprouting/sell new buds in this weather. The two striped cats seemed to fight/fighting/tap all the time at the farm. The undercover cop will inform/informing/range the actor during the raid. The villagers needed to fish/fishing/treat in order to survive the winter. The volunteers offered to repair/repairing/square the house for the family. The waitress will serve/serving/shock the dinner in a few minutes. The wallpaper was removed so the housewife could decorate/decorating/topple the wall. The workmen in the ditch planned to dig/digging/inspire all the way to the pipe. The young horse looked so fast that the gambler might bet/betting/twist on him. The young lion is going to claw/clawing/type the baboon on the rock. These types of grapev ines do not fruit/fruiting/jog well in sandy regions. This exotic spice may add/adding/seek the oriental flavor that John enjoys.

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155 This expensive ointment will cure/curing/loathe all known forms of skin disease. This old electric blender does not crush/c rushing/own ice cubes anymore. This rare herb can heal/healing/count the pains in your back. This test of reasoning might fail/failing/hate to discriminate among students. William thought that he would fit/fitting/dig right in with the crowd at the rece ption.

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156 APPENDIX B WHOLE SENTENCE STIMU LI WITH COMPREHENSIO N QUESTIONS Whole Sentences (nonanomalous / syntactic anomaly / semantic anomaly) Nonanomalous Questions Syntactic Questions Semantic Questions At the aquarium, there are otters that swim / swim ming / fly and do tricks for the crowds. Does the aquarium have otters? Is the aquarium missing otters? Does the aquarium have otters? Is the aquarium missing otters? Does the aquarium have otters? Is the aquarium missing otters? Billy bumped his bicycle, causing it to land / landing / sneeze into the street. Did the bicycle land in the street? Did the bicycle land on the sidewalk? Did the bicycle land in the street? Did the bicycle land on the sidewalk? Did the bicycle sneeze into the street? Did the bicycl e sneeze into the sidewalk? Fountain pens should not be used to sketch / sketching / dust since they were designed only for writing. Were fountain pens designed for writing? Were fountain pens designed for sketching? Were fountain pens designed for writing? Were fountain pens designed for sketching? Were fountain pens designed for writing? Were fountain pens designed for sketching? In case of a break in, the alarm system will warn / warning / swear that there is an intruder. Will the alarm system warn that th ere is an intruder? Will the alarm system warn that there is a storm? Will the alarm system warn that there is an intruder? Will the alarm system warn that there is a storm? Will the alarm system swear that there is an intruder? Will the alarm system swear that there is a storm? landfills, chemicals of different sorts may mix / mixing / hope to create lethal substances. Do chemicals mix in the nation's landfills? Do chemicals mix in the nation's parks? Do chemicals hope to create lethal subst ances in the nation's landfills? Do chemicals hope to create lethal substances in the nation's parks? Do chemicals hope to create lethal substances in the nation's landfills? Do chemicals hope to create lethal substances in the nation's parks?

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157 One kangaro o at the San Diego Zoo would sometimes hop / hopping / write all day. Will the kangaroo sometimes hop all day? Will the kangaroo always hop all day? Will the kangaroo sometimes hop all day? Will the kangaroo always hop all day? Will the kangaroo sometimes wr ite all day? Will the kangaroo always write all day? People hope that the sculpture will inspire / inspiring / invent new forms of artistic expression. Will the sculpture possibly inspire new forms of artistic expression? Will the sculpture definitely inspi re new forms of artistic expression? Will the sculpture possibly inspire new forms of artistic expression? Will the sculpture definitely inspire new forms of artistic expression? Will the sculpture possibly invent new forms of artistic expression? Will the sculpture definitely invent new forms of artistic expression? Physicists will study / studying / lock the long report that arrived yesterday morning. Did the long report arrive yesterday? Did the long report arrive today? Did the long report arrive yesterd ay? Did the long report arrive today? Did the long report arrive yesterday? Did the long report arrive today? She has a rag to dust / dusting / act the living room already. Does she have a rag to dust the room? Does she have a maid to dust the room? Does sh e have a rag to dust the room? Does she have a maid to dust the room? Does she have a rag to clean the room? Does she have a maid to clean the room? The accountant will deliver / delivering / string the reports on the embezzlement to the detective. Will the accountant deliver the reports? Will the accountant deliver the checkbook? Will the accountant deliver the reports? Will the accountant deliver the checkbook? Will the accountant deliver the reports? Will the accountant deliver the checkbook? The award w inning play will run / running / leap for several more months. The play will run for several more months. The play will run for several more years. The play will run for several more months. The play will run for several more years. The play will run for sev eral more months. The play will run for several more years.

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158 The babies will cry / crying / graduate because they are hungry for their dinner. Will the babies cry because they are hungry? Will the babies sleep because they are hungry? Will the babies cry bec ause they are hungry? Will the babies sleep because they are hungry? Will the babies cry because they are hungry? Will the babies sleep because they are hungry? The baker wants to bake / baking / cast a wedding cake for the couple. Does the baker want to ba ke a wedding cake? Does the baker want to bake a ham? Does the baker want to cast a wedding cake? Does the baker want to cast a ham? Does the baker want to cast a wedding cake? Does the baker want to cast a ham? The beavers in the pond sometimes chew / che wing / melt the garden hose. Will the beavers occasionally chew the hose? Will the beavers always chew the hose? Will the beavers occasionally chew the hose? Will the beavers always chew the hose? Will the beavers occasionally melt the hose? Will the beaver s always melt the hose? The bored audience might watch / watching / button the new show and dance routine. Will the audience possibly watch the new show? Will the audience definitely watch the new show? Will the audience possibly watch the new show? Will th e audience definitely watch the new show? Will the audience possibly button the new show? Will the audience definitely button the new show? The boxes in the attic may still hold / holding / find many old photographs and souvenirs. Do the boxes in the attic possibly hold old photographs? Do the boxes in the attic definitely hold old photographs? Do the boxes in the attic possibly hold old photographs? Do the boxes in the attic definitely hold old photographs? Do the boxes in the attic possibly find old photog raphs? Do the boxes in the attic definitely find old photographs? The bull that escaped could smash / smashing / send the wooden fence around the meadow. Will the bull possibly smash the fence around the meadow? Will the bull definitely smash the fence arou nd the meadow? Will the bull possibly smash the fence around the meadow? Will the bull definitely smash the fence around the meadow? Will the bull possibly send the fence around the meadow? Will the bull definitely send the fence around the meadow?

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159 The bu tcher will chop / chopping / influence the meat for the long line of customers. Will the meat be chopped for the customers? Will the vegetables be chopped for the customers? Will the meat be chopped for the customers? Will the vegetables be chopped for the c ustomers? Will the meat be chopped for the customers? Will the vegetables be chopped for the customers? The chatting students tried to ignore / ignoring / fence the scowling librarian at the desk. Did the chatting students try to ignore the librarian? Did t he chatting students try to chat with the librarian? Did the chatting students try to ignore the librarian? Did the chatting students try to chat with the librarian? Did the chatting students try to ignore the librarian? Did the chatting students try to ch at with the librarian? The competitors will race / racing / age in the field with a large audience. Will the field have a large audience? Will the field have a small audience? Will the field have a large audience? Will the field have a small audience? Will the field have a large audience? Will the field have a small audience? The composer agreed that his music should enchant / enchanting / question the public. Did the composer agree about his music? Did the composer disagree about his music? Did the composer agree about his music? Did the composer disagree about his music? Did the composer agree about his music? Did the composer disagree about his music? The constable might question / questioning / cost the man from the convenience store. Will the constable pos sibly question the man? Will the constable definitely question the man? Will the constable possibly question the man? Will the constable definitely question the man? Will the constable possibly cost the man? Will the constable definitely cost the man? The critic plans to complain / complaining / shop about the temperature of the meat. Does the critic plan to complain? Does the critic plan to leave? Does the critic plan to complain? Does the critic plan to leave? Does the critic plan to shop? Does the critic plan to leave?

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160 The electrician will plug / plugging / spell the ceiling fan in when the power turns on. Will the electrician spell the fan? Will the electrician unplug the fan? Will the electrician plug in the fan? Will the electrician unplug the fan? Will the electrician spell the fan? Will the electrician unplug the fan? The essay was due, so the student had to type / typing / gaze all night. Did the student type all night? Did the student sleep all night? Did the student type all night? Did the student sle ep all night? Did the student gaze all night? Did the student sleep all night? The fingerprints on the gun could prove / proving / judge that the defendant is innocent. Will the fingerprints on the gun possibly prove the defendant's innocence? Will the fing erprints on the gun definitely prove the defendant's innocence? Will the fingerprints on the gun possibly prove the defendant's innocence? Will the fingerprints on the gun definitely prove the defendant's innocence? Will the fingerprints on the gun possibl y judge the defendant's innocence? Will the fingerprints on the gun definitely judge the defendant's innocence? The flan might burn / burning / despair badly if the cook leaves the room. Will the flan possibly burn badly? Will the flan definitely burn badly ? Will the flan possibly burn badly? Will the flan definitely burn badly? Will the flan possibly despair badly? Will the flan definitely despair badly? The fugitive has to hide / hiding / repeat at the railway for a few months. Will the fugitive repeat at t he railway? Will the fugitive repeat at the bus stop? Will the fugitive hide at the railway? Will the fugitive hide at the bus stop? Will the fugitive repeat at the railway? Will the fugitive repeat at the bus stop? The gambler would cheat / cheating / soun d the system if he could count cards. Would the gambler cheat the system? Would the gambler always obey the rules? Would the gambler cheat the system? Would the gambler always obey the rules? Would the gambler sound the system? Would the gambler always obe y the rules?

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161 The general admits that the missile might explode / exploding / call before leaving the area. Did the general admit that the missile might explode? Did the general admit that the missile will definitely explode? Did the general admit that the m issile might explode? Did the general admit that the missile will definitely explode? Did the general admit that the missile might call? Did the general admit that the missile will definitely call? The girl could hear / hearing / alter the music from two ho uses away. Did the girl want to hug her brother? Did the girl want to push her brother? Did the girl want to hug her brother? Did the girl want to push her brother? Did the girl want to ticket her brother? Did the girl want to push her brother? The hidden door will open / opening / cook when the secret code is spoken. Will the hidden door open with a secret code? Will the hidden door open with a key? Will the hidden door open with a secret code? Will the hidden door open with a key? Will the hidden door cook with a secret code? Will the hidden door cook with a key? The high court will judge / judging / wish whether he was wrong or not. Will the high court judge him? Will the high court avoid judgement? Will the high court wish him? Will the high court avoid wi shing? Will the high court wish him? Will the high court avoid wishing? The hikers noticed that the boulder seemed to rest / resting / live precariously on the mountain. Did the hikers notice the boulder resting precariously? Did the hikers notice the bould er resting securely? Did the hikers notice the boulder resting precariously? Did the hikers notice the boulder resting securely? Did the hikers notice the boulder resting precariously? Did the hikers notice the boulder resting securely? The housewife in t he kitchen had to bake / baking / enchant the cake early. Did the housewife enchant the cake early? Did the housewife enchant the cake late? Did the housewife bake the cake early? Did the housewife bake the cake late? Did the housewife enchant the cake early ? Did the housewife enchant the cake late? The inventive dancer might perform / performing / sketch a new routine for the crowd. Will the dancer possibly perform a new routine? Will the dancer definitely perform a new routine? Will the dancer possibly perfo rm a new routine? Will the dancer definitely perform a new routine? Will the dancer possibly sketch a new routine? Will the dancer definitely sketch a new routine?

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162 The investigation will persist / persisting / fry until the journalist finds real answers. Wi ll the investigation continue until answers are found? Will the investigation stop until answers are found? Will the investigation fry until answers are found? Will the investigation stop until answers are found? Will the investigation fry until answers ar e found? Will the investigation stop until answers are found? The lead singer did practice / practicing / space the badly performed song a few times. Did the lead singer practice the song a few times? Did the lead singer forget to practice the song a few ti mes? Did the lead singer practice the song a few times? Did the lead singer forget to practice the song a few times? Did the lead singer space the song a few times? Did the lead singer forget to space the song a few times? The local beers in Seattle will satisfy / satisfying / trip every beer drinker. Will the beers satisfy every beer drinker? Will the beers disappoint every beer drinker? Will the beers satisfy every beer drinker? Will the beers disappoint every beer drinker? Will the beers trip every beer d rinker? Will the beers disappoint every beer drinker? The loud reporter might annoy / annoying / beach the performers on the stage. Will the reporter possibly annoy the performers? Will the reporter definitely annoy the performers? Will the reporter possibl y annoy the performers? Will the reporter definitely annoy the performers? Will the reporter possibly beach the performers? Will the reporter definitely beach the performers? The maids clean / cleaning / trace the house while the family is away. Will the ma ids clean the house? Will the maids trash the house? Will the maids clean the house? Will the maids trash the house? Will the maids clean the house? Will the maids trash the house? The man next door does own / owning / carpet his own boat at the lake. Does the man next door own his own boat? Does the man next door rent his own boat? Does the man next door own his own boat? Does the man next door rent his own boat? Does the man next door carpet his own boat? Does the man next door rent his own boat? The meet ing with the politician will continue / continuing / scratch in a few minutes. Will the meeting continue in a few minutes? Will the meeting continue in a few days? Will the meeting continue in a few minutes? Will the meeting continue in a few days? Will the meeting continue in a few minutes? Will the meeting continue in a few days?

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163 The newlywed couple will dance / dancing / port first on the dance floor. Will the newlywed couple dance first? Will the newlywed couple dance third? Will the newlywed couple dance first? Will the newlywed couple dance third? Will the newlywed couple port first? Will the newlywed couple port third? The noisy ducks will soon waddle / waddling / skip away from the lake. Will the manager possibly budget for a party? Will the manager defi nitely budget for a party? Will the manager possibly budget for a party? Will the manager definitely budget for a party? Will the manager possibly impact for a party? Will the manager definitely impact for a party? The pickpocket might flee / fleeing / sing from the policeman down the alley. Will the pickpocket possibly flee down the alley? Will the pickpocket possibly flee down the stairs? Will the pickpocket possibly flee down the alley? Will the pickpocket possibly flee down the stairs? Will the pickpocke t possibly sing down the alley? Will the pickpocket possibly sing down the stairs? The publisher wants the author to edit / editing / harm the novel again. Does the publisher want the author to edit the novel? Does the publisher want the author to trash the novel? Does the publisher want the author to edit the novel? Does the publisher want the author to trash the novel? Does the publisher want the author to harm the novel? Does the publisher want the author to edit the novel? The raging bull will soon char ge / charging / whistle at the waiting man. Will the raging bull charge soon? Will the raging bull charge later? Will the raging bull charge soon? Will the raging bull charge later? Will the raging bull whistle soon? Will the raging bull whistle later? The receptionist will call / calling / reason all the clients in the afternoon. Will the receptionist call all the clients? Will the receptionist fax all the clients? Will the receptionist call all the clients? Will the receptionist fax all the clients? Will the receptionist reason with all the clients? Will the receptionist fax all the clients?

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164 The report on the desk does describe / describing / steam the incident in great detail. Does the report describe the incident in detail? Does the report describe the incid ent without much detail? Does the report steam the incident in detail? Does the report steam the incident without much detail? Does the report steam the incident in detail? Does the report steam the incident without much detail? The retired gymnast will c oach / coaching / guess the athletes for the high school. Will the gymnast coach the athletes? Will the gymnast coach the debate team? Will the gymnast coach the athletes? Will the gymnast coach the debate team? Will the gymnast coach the athletes? Will the gymnast coach the debate team? The rude crowd might interrupt / interrupting / stake the shy singer at the bar. Will the crowd possibly interrupt the singer? Will the crowd definitely interrupt the singer? Will the crowd possibly interrupt the singer? Will the crowd definitely interrupt the singer? Will the crowd possibly stake the singer? Will the crowd definitely stake the singer? The scientist thinks that the lab is supposed to research / researching / neglect the problem more thoroughly. Does the scientis t think the lab should neglect the problem thoroughly? Does the scientist think the lab should never neglect the problem? Does the scientist think the lab should neglect the problem thoroughly? Does the scientist think the lab should never neglect the prob lem? Does the scientist think the lab should neglect the problem thoroughly? Does the scientist think the lab should never neglect the problem? The scouts planned to camp / camping / cure at the national park next winter. Do the scouts plan to camp at the n ational park? Do the scouts plan to camp at the house? Do the scouts plan to camp at the national park? Do the scouts plan to camp at the house? Do the scouts plan to cure at the national park? Do the scouts plan to cure at the house? The sea lions can ba sk / basking / edit on the beach all day. Will the sea lions possible bask all day? Will the sea lions definitely bask all day? Will the sea lions possible bask all day? Will the sea lions definitely bask all day? Will the sea lions possible edit all day? Wi ll the sea lions definitely edit all day?

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165 The skipper in the boat will sail / sailing / match to the dock. Will the skipper sail to the dock? Will the skipper swim to the dock? Will the skipper match to the dock? Will the skipper swim to the dock? Will the skipper match to the dock? Will the skipper swim to the dock? The skyscraper being built by the city would block / blocking / send out the sunlight. Will the skyscraper block out the sunlight? Will the skyscraper block out the garden? Will the skyscraper bl ock out the sunlight? Will the skyscraper block out the garden? Will the skyscraper send out the sunlight? Will the skyscraper send out the garden? The soccer player wanted to jog / jogging / whisper in order to warm up. Did the soccer player want to jog? D id the socker player want to rest? Did the soccer player want to jog? Did the socker player want to rest? Did the soccer player want to whisper? Did the socker player want to rest? The solitary dancer might leap / leap / rule across the stage for the next s cene. Will the dancer possibly leap across the stage? Will the dancer definitely leap across the stage? Will the dancer possibly leap across the stage? Will the dancer definitely leap across the stage? Will the dancer possibly rule across the stage? Will t he dancer definitely rule across the stage? The stage actor will complete / completing / calm the ending of the scene as planned. Will the actor calm the ending of the scene? Will the actor stop performing before the end? Will the actor complete the ending of the scene? Will the actor stop performing before the end? Will the actor calm the ending of the scene? Will the actor stop performing before the end? The strawberry beds might tempt / tempting / sneeze rabbits and other hungry animals. Will the strawberr y beds possibly tempt the rabbits? Will the strawberry beds definitely tempt the rabbits? Will the strawberry beds possibly tempt the rabbits? Will the strawberry beds definitely tempt the rabbits? Will the strawberry beds possibly sneeze rabbits? Will the strawberry beds definitely sneeze rabbits? The student might crease / creasing / poison the paper to take better notes. Will the student possibly crease the paper? Will the student definitely crease the paper? Will the student possibly crease the paper? Wi ll the student definitely crease the paper? Will the student possibly poison the paper? Will the student definitely poison the paper?

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166 The supervisor of the plant wanted to observe / observing / top the work of the technician. Did the supervisor want to top the work of the technician? Did the supervisor want to do the work of the technician? Did the supervisor want to observe the work of the technician? Did the supervisor want to do the work of the technician? Did the supervisor want to top the work of the te chnician? Did the supervisor want to do the work of the technician? The teacher said our report must not last / lasting / cry for more than ten minutes. Should the report last no more than ten minutes? Should the report last longer than ten minutes? Should the report last no more than ten minutes? Should the report last longer than ten minutes? Should the report cry no more than ten minutes? Should the report cry longer than ten minutes? The therapist hoped that the new drug would calm / calming / clean the p atient who was so anxious. Did the therapist hope the drug would clean the patient? Did the therapist hope the drug would excite the patient? Did the therapist hope the drug would calm the patient? Did the therapist hope the drug would excite the patient? Did the therapist hope the drug would clean the patient? Did the therapist hope the drug would excite the patient? The toddler needed to cough / coughing / lean after smelling the smoke in the kitchen. Did the toddler need to cough after smelling smoke? Did the toddler need to swim after smelling smoke? Did the toddler need to cough after smelling smoke? Did the toddler need to swim after smelling smoke? Did the toddler need to lean after smelling smoke? Did the toddler need to swim after smelling smoke? Th e tree branch will break / breaking / lecture if the wind is too strong. Will the tree branch break if the wind is too strong? Will the tree branch break if there is no wind? Will the tree branch break if the wind is too strong? Will the tree branch break if there is no wind? Will the tree branch lecture if the wind is too strong? Will the tree brach lecture if there is no wind? The truck driver will park / parking / finish in the street and not the driveway. Will the truck driver park in the street? Will the truck driver park in the driveway? Will the truck driver finish in the street? Will the truck driver finish in the driveway? Will the truck driver finish in the street? Will the truck driver finish in the driveway?

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167 The underpaid comedian will perform / per forming / heal until the last guest leaves. Will the comedian perform? Will the comedian sleep? Will the comedian perform? Will the comedian sleep? Will the comedian perform? Will the comedian sleep? The vacuum in the storage room should clean / cleaning / s ketch all the furniture. Will the vacuum sketch the furniture? Will the vacuum stain the furniture? Will the vacuum clean the furniture? Will the vacuum stain the furniture? Will the vacuum sketch the furniture? Will the vacuum stain the furniture? The vo lunteer coach will evaluate / evaluating / knit the performance of each player. Will the coach evaluate each performance? Will the coach evaluate each exam? Will the coach evaluate each performance? Will the coach evaluate each exam? Will the coach knit each performance? Will the coach knit each exam? The woman wanted to hate / hating / shell her, but she enjoyed her company too much. Did the woman enjoy her company? Did the woman hate her? Did the woman enjoy her company? Did the woman hate her? Did the woman enjoy her company? Did the woman hate her? Those small spiders would often spin / spinning / burn beautiful webs in the trees. Do the small spiders often spin beautiful webs? Do the small spiders often spin ugly webs? Do the small spiders often spin beauti ful webs? Do the small spiders often spin ugly webs? Do the small spiders often burn beautiful webs? Do the small spiders often burn ugly webs? We hoped that the news of the award would cheer / cheering / wash up the depressed student. Will the award possi bly cheer up the student? Will the award definitely cheer up the student? Will the award possibly cheer up the student? Will the award definitely cheer up the student? Will the award possibly wash up the student? Will the award definitely wash up the stude nt?

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168 Where the road forks / forking / believes, we could not figure out which way to go. Could they not figure out which way to go? Could they figure out which way to go? Could they not figure out which way to go? Could they figure out which way to go? Could they not figure out which way to go? Could they figure out which way to go?

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169 APPENDIX C RSVP SENTENCE FILLER S WITHOUT COMPREHENS ION QUESTIONS RSVP Filler Sentences The accident destroyed the new tire in a few seconds. The adult posted the reward for the lost pet in the newspaper. The air force commander bombed the enemies that were in a pit. The army tank shot the weapon shed of the terrorist organization. The artistic sketch pictured a green pasture out in the country. The aspiring poet typed a trail of words on the page. The bakery cook broke an egg white into the cookie dough. The band calmed the rowdy observers at the sporting event. The baseball player touched the ball with a light tap of the bat. The battle damaged the fleet of naval ships off the coast. The beginning pianist sold his old violin in the music store. The big bubble narrowly escaped the pointy branch of the tree. The biology professor measured the large wing of the rare bird. The breeze flowed through the sails of the large boat. The bright lightning blinded the scared passengers on the bus. The brown calf played with his herd in the shadow of the tree. The business convention misinterpreted the fiscal profile of the company last year. The buzzing bees flew over th e top of the pond. A mosquito landed on the netted food near the campers. The cardboard box sheltered the homeless native from the rain shower. The clever customer determined the freight of the boxed cargo. The cloud caught the colorful tip of the rain bow in the sky. The cold whiskey filled the short cup to the rim. The college student is learning about the aliens through a novel. The construction worker pulled the toast out of the toaster for breakfast. The construction team drilled the metal rod i nto the ground. The costumer designed the cake for the birthday party that night. The couple sought out the perfect couch for their new apartment.

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170 My cousin bought me a vacuum from the department store. The crowd judged the man based on the size of his waist. The dangerous criminal plotted a murder and burial behind his family's back. The dentist commanded the servant that worked in the mansion. The detective voiced his concern for the woman over the phone. The driver threw a green apple out of the window at an angle. The established painter sent the romantic portrait to the museum in Philadelphia. The experienced sergeant controlled the massive fort and all of the officers. The experienced detective questioned the suspect in the expensive suite. The experienced guide scaled the treacherous cliff with ease on the hike. The fad diet promised a short round of rapid results. The famous poet wrote the brief passage at the beginning of the book. The fashion magazine considered a segment on winter we ar for the cover story. The fast hawk attacked the small animal over the sea. The flash flood destroyed all of the lodges in the area. The flat prairie circled the camp on the outskirts of town. The floats rode down a one lane road throughout the parad e. The flowered stems framed the elegant arch in the castle garden. The frame would not stick to the wall with just tape. The gated entrance rose out of the forest wilderness in the north. The genuine smile shaped the drama between the two sisters. Th e grandfather trusted the workers in the day care center with his granddaughter. The group of knights crowded into the fort before they left. A professional styled the outlandish outfit of the guest speaker. The hard fight secured the weapons from the b uilding in the village. The horse drawn carriage parked at the curb near the tourists. The hungry flock ate the lush grass in the plentiful field. The iron gate met the picket fence at the front of the property. The judge filed a bunch of legal paperwo rk at the courthouse. The judges rated the band and composer with a perfect score. The kind nurse comforted the sick patient in the waiting room. The large vessel silenced the prayers of the people in town.

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171 The lawyer was seated at the bar with a drink in hand. The lean messenger turned the red shoes so they would fit better. The lightning struck the tall bridge on Tuesday night during the storm. The link to the city aided the goals of the governor. The lip synched tune fooled the ecstatic fans at t he concert. I listened carefully to the loud thunder and pelting hail. The long pipe oiled the drawbridge near the hinges at the front. The long train on the track weighed a sum of one hundred thousand pounds. The loud orchestra blocked out the opera s inger's beautiful voice. The lounge singer saved her wages to pay off her loans. The man farmed the land with a tractor and a rake. The mare landed the impressive jump in the amateur competition. The captain guided the massive ship through the dangerou s cape. The master watched carefully over his fish in the large tank. The military raid defeated a large branch of the terrorist organization. The mold hated the intense heat of the arid environment. My mother cooked fried fish for dinner and apple pie for dessert. The motor forced the gas through the pistons in the car. The movie recalled the birth of one of the greatest inventions of all time. The movie star murdered her mate in the horror film. The new coach traded his worst player in order to be come a champion. The new treasurer improved the financial disaster by holding many fundraisers. The news channel taped the natural disaster from a distance. The next speaker counted the watches on the front table. The novel listed the lofty goals of th e main character. The old rug joined the pile of linens at the garage sale. The old woman called the front desk of the resort for tea. The old rabbi replied to the letter with a short prayer. The older gentleman carried the worn saddle to the stables f or the ride. The painter emptied the new package of art supplies onto the table. A parade of tractors rolled through the center of town. The patriotic lieutenant battled the enemy with his men in the desert.

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172 The people were angered by the buzzing bee t hat was on the bush. The pony smelled the green grass on top of the hill. The prestigious institute reviewed the pile of applications for the teaching position. The prestigious bank assisted the flock of eager investors after hours. The princess pocket ed her private journal in the crowded room. The prison guard signaled to the inmate with a hand sign. The promising candidate failed the important interview on Tuesday afternoon. The protruding pipe tripped the tourist in the hotel room. The purple bal loon crossed the green valley after sunset on Wednesday evening. The quiet grandfather reached the old library just in time. The receiver hurt his shoulder before the football game in Tennessee. The red barn held the winning pony from the contest. The refrigerated trailer shipped the specialty beef across the country. The renowned poet spoke about the Italian landscape in his greatest work. The researchers tested the new drug with a series of tests on the nose. The resounding echo trailed the noisy c amp of summer vacationers. The respected scholar remarked about the new design for the engine. The robed priest disputed the segment of the document about the church. The rocky soil lined the slope of the tall mountain. I completed a large jigsaw puzzl e in the ski lodge during the blizzard. The science professor named the planet in the distant galaxy. The scientific tool fired a powerful beam of charged protons. The navy stationed the seaman on the quiet sea base. The seasoned farmer planted green p eppers in the fertile valley. The seasoned commander watched his troops with a pair of keen eyes. The ship was grounded on the east coast of Florida. The signal noted the steep curve in the road up ahead. The skilled builder engineered the decorative m antle above the fireplace. The small store feared the financial drain of the poor economy. The soccer match leveled a track of grass on the playing field. The spark rode the stem of the fuse on the explosive. The sticky mud covered the dairy farm after the spring rains.

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173 The stiff collar of my shirt brushed against my palm. My strict aunt quieted my three brothers in the carpet store. The talented builder developed a new roof for the church. The tank raced the roll of rapid gunfire in the war zone. The teacher phoned the library for a book about organs. The team secured the loose lumber before the arrival of the storm. The thick smoke passed the cape of the island after the volcanic eruption. The tired pupil dreamed of more comfortable furniture f or his dorm room. We tracked our distance on foot with a computerized map. The triple jump beat the lateral twist in the figure skating competition. The unhappy queen suspected the flowers on her table because of the smell. The unhealthy diet increased the weight of the participants in the study. The visitor mailed the envelope at the post office on Thursday. The visitor tasted the savory steak at the new restaurant. The warm sunlight heated the small lake in the summer. The water from the fountain cooled the sweaty foot of the child. The wheel of the car missed the platform by an inch. The wind storm moved across the small kingdom at a quick pace. The witness viewed a photograph of the criminal in court. The dress design called for a narrow skir t down to the ankle. The woman's salary was wasted on skirts, shoes, and jewelry. The young princess and elegant queen exchanged glances over the table. The young teacher challenged her class with a heap of difficult assignments. The young woman was tr oubled by her dream that was about an assault. The young boy motioned to the scar on his elbow with sad eyes. The hostile natives claimed their land from the new settlers.

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174 APPENDIX D WHOLE SENTENCE TASK FILLERS WITH COMPREH ENSION QUESTIONS Whole Fill er Sentences The hot steam from the shower kept the suite warm. Did the steam keep the suite cool? Did the steam keep the suite warm? The lively seal traveled towards the sunset near the shore. Did the lively seal travel t owards the sunrise? Did the lively seal travel towards the sunset? The needle stick transferred the deadly poison from the frog. Did the needle stick cure the poison? Did the needle stick transfer the poison? The doctor financed his medical school educat ion with money from an accidental injury. Was the education paid for with money from a scholarship? Was the education paid for with money from an accidental injury? The church minister permitted the tourist group to see the service. Did the tourist group miss the service? Did the tourist group see the service? The flood killed many plants and animals in the kingdom. Did the flood kill few plants? Did the flood kill many plants? The large orchestra stayed in the resort after the concert series. Did the or chestra stay in the lodge? Did the orchestra stay in the resort? The coach rewarded his new team with a pint of ice cream. Did the coach give his team warm up drills? Did the coach give his team ice cream? The hysterical laughter summarized the comical s ketch of the politician in the paper. Was there a professional portrait of the politician? Was there a comical sketch of the politician? The repairman rewired the phone line in the new apartment. Was the phone line disconnected? Was the phone line rewired ?

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175 The black bear fought the large creature in the forest. Did the black bear fight in the meadow? Did the black bear fight in the forest? The rough tide rocked the small ferry back and forth. Was the ferry sitting calmly on the water? Was the ferry rocki ng on the water? The rich lawyer welcomed his new clients over to his desk. Did the lawyer welcome his partners? Did the lawyer welcome his clients? The tent moved around our campsite with the calm breeze. Did the tent blow into the lake? Did the tent bl ow around the campsite? The adult interviewed the witness on trial in the courtroom. Did the adult interview the witness in the office? Did the adult interview the witness in the courtroom? The tired server stepped with a limp up the stairs. Did the serv er limp up the sidewalk? Did the server limp up the stairs? The loud motor shook the flimsy trailer in the parking lot. Did the motor shake the car? Did the motor shake the trailer? The marinated steak supplied the savory juice for the gravy. Did the roa st supply the juice for the gravy? Did the steak supply the juice for the gravy? The priest administered the written prayer in church on Sunday. Did the nun administer the written prayer? Did the priest administer the written prayer? The lieutenant plann ed the entire conference for the military academy. Did the cadet plan the conference? Did the lieutenant plan the conference? The elegant dancer won a medal and became the state champion. Did the soccer player win a medal? Did the dancer win a medal?

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176 The green mold grew on the fruit left out overnight. Did the mold grow on the bread? Did the mold grow on the fruit? The policeman searched for his harness in his messy car. Did the policeman search for his badge? Did the policeman search for his harness? T he young doctor showed the hospital nursery to the new parents. Did the nurse show the nursery to the parents? Did the doctor show the nursery to the parents? The small insect laid on the forehead of the man. Did the insect lay on the man's arm? Did the i nsect lay on the man's forehead? The friendly nurse smiled at her new patient in the hospital. Did the nurse frown at her patient? Did the nurse smile at her patient? The judge stored the bottles of alcohol in the cabinet behind the desk. Did the judge s tore soda? Did the judge store alcohol? The boss smoothed out the quarrel with a lame joke. Did the employee smooth out the quarrel? Did the boss smooth out the quarrel? The sad minister stood alone outside of the tiny cottage. Did the minister stand ins ide the cottage? Did the minister stand outside the cottage? The accomplished musician taught the aspiring pianist on Monday afternoons. Did the musician teach the violinist? Did the musician teach the pianist? The travelling scholar glimpsed the ship in the distance from the port. Did the scholar glimpse a port? Did the scholar glimpse a ship? The federal government taxes liquor in order to build an empire. Does the government ban liquor? Does the government tax liquor?

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177 The new steel decreased the weig ht of the heavy automobile. Did the steel increase the weight? Did the steel decrease the weight? The anchor dropped into the sand to keep the boat still in the bay. Did the anchor drop into the deck? Did the anchor drop into the sand? The busy sergeant marked the card with his personal stamp yesterday. Was the card marked with his signature? Was the card marked with his stamp? The fabric of the shirt matched the texture of the long skirt. Did the shirt clash with the skirt? Did the shirt match the skirt ? The political convention displayed a bar graph of the results on the computer. Were the results shown on a line graph? Were the results shown on a bar graph? The talented composer expressed his emotions and ideas through a string of music. Were his emo tions expressed through writing? Were his emotions expressed through music? The woman strained to see the moon that was on the bay's horizon. Was the moon on the field's horizon? Was the moon on the bay's horizon? The art institute picked the winning por trait of the woman. Did the woman pick the winning portrait? Did the art institute pick the winning portrait? The travel guide lost the troop of tourists in the busy city. Did the travel guide lose the keys? Did the travel guide lose the tourists? The me tal revolver was loaded in case there was a robbery. Was the revolver unloaded? Was the revolver loaded? The powerful drill neared the oil deep under the ground. Was the drill getting close to water? Was the drill getting close to oil?

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178 The brown hawk bit the trainer on her left cheek. Did the hawk scratch the trainer? Did the hawk bite the trainer? The new jury examined the evidence for a gruesome murder. Did the jury ignore the evidence? Did the jury examine the evidence? The robbery victim guarded the stables for hours after the incident. Did the victim guard the house? Did the victim guard the stables? The leader returned the dinner plate after he was finished. Did the leader keep the plate? Did the leader return the plate? The innovative musician s ang the famous passage from the Shakespearian play on stage. Did the musician sing a passage from Mozart? Did the musician sing a passage from the Shakespearian play? The famous actress wore a dress to the movie premier. Did the actress wear pants to the premier? Did the actress wear a dress to the premier? The malicious post shocked the humble candidate in the campaign. Did the post calm the candidate? Did the post shock the candidate? The keen observer reported accurate information of the quarrel to th e news team. Was the information reported inaccurately? Was the information reported accurately? The aluminum foil protected the slice of pizza in the refrigerator. Was the pizza in the freezer? Was the pizza in the refrigerator? The kindergarten student drew a circle on the hot cement. Did the student draw a square? Did the student draw a circle? The server boxed the tray of delicious food for the guests. Did the chef box the food for the guests? Did the server box the food for the guests?

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179 The new empl oyee was trained on the register at the store. Was the new employee trained at the meeting? Was the new employee trained at the store? The metal rail supported the ski lift on the mountain. Did the metal rail support the bridge? Did the metal rail support the ski lift? The sharp knife split the fresh pork at the dinner table. Did the knife split the ham? Did the knife split the pork? The enemy submarine surfaced along the coast early yesterday morning. Did the submarine surface last night? Did the submar ine surface yesterday? The English teacher graded the spelling test with a pencil. Did the teacher grade the test with a pen? Did the teacher grade the test with a pencil? The narrow corridor stopped at the edge of the small living room. Did the corridor stop at the edge of the dinning room? Did the corridor stop at the edge of the living room? The officer's bark advanced the fleet of war ships along the coast. Did the officer's bark cause the ships to retreat? Did the officer's bark cause the ships to a dvance? The movie star chose a fancy ring for her engagement. Did the singer choose a ring? Did the movie star choose a ring? The cracked bell in the town rang loudly throughout the crowd. Did the bell ring softly? Did the bell ring loudly? The strange creature surprised the troop of explorers in the rainforest. Did the creature surprise the tourists? Did the creature surprise the explorers? The bright red cardinal quietly approached the covered porch for bird seed. Did the cardinal approach the garden ? Did the cardinal approach the porch?

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180 The alien built the flying vessel from materials in outer space. Was the vessel built from materials from Earth? Was the vessel built from materials in outer space? The disciplined guard raised his gun toward the da ngerous driver. Did the guard lower his gun? Did the guard raise his gun? The wide receiver patted the sweat on his forehead with a towel. Was his forehead dry? Was his forehead sweaty? The talented pupil painted the fruit in the still life. Did the pupi l paint the vase? Did the pupil paint the fruit? The tall oak tree pushed the root into the ground. Did the root push into the house? Did the root push into the ground? The black button matched the dark wool on the coat. Did the button match the cotton? Did the button match the wool? The foreign enemy desired the jeweled purse of the queen of Scotland. Did the enemy desire the shoes? Did the enemy desire the purse? The experienced panel of engineers voted for the funniest joke. Did the engineers vote on the design? Did the engineers vote on the joke? The long tunnel through the mountain cut the mileage in half. Was the mileage doubled? Was the mileage cut in half? The policeman issued a statement about the robbery at the bank. Was the statement about t he kidnapping? Was the statement about the robbery?

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196 BIOGRAPHICAL SKETCH Sarah Key-DeLyria received her Bachelor of Arts in linguistics and c ognitive sciences from Rice University in Houston, Texas, her hometown, in 2004. It was while at Rice that she first became interested in speech-language pathology research. She earned her Master of Arts in speech-language pathology from The University of Texas at Austin in 2006 where she studied aphasia treatment with Swathi Kiran and acquired apraxia of speech with Thomas Marquardt. While earning her Doctor of Philosophy at the University of Florida, she conducted research on cognition and language in the Language over the Lifespan Lab with Lori Altmann and in the Clinical-Cognitive Neuroscience Lab using electroencephalography (EEG) with William Perlstein. She has presented several posters and given talks about her research at national and international conferences. She also earned clinical certification in speech-language pathology from the American Speech-Language-Hearing Association (ASHA) while completing her studies.