1 VERB AND THEMATIC ROLES PRIMING IN YOUNGER AND OLDER ADULTS: IMPLICATIONS FOR SEMANTIC PROCESSING By SARA E. MIZRAHI A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQ UIREMENTS FOR THE DEGREE OF MASTER OF ARTS UNIVERSITY OF FLORIDA 2009
2 2009 Sara E. Mizrahi
3 To my Parents
4 ACKNOWLEDGMENTS I appreciate all the support I have received over the course of working on t his project. I thank my committee, who have continuously challenged and inspired me to think independently and apply my knowledge. I thank my parents, fianc, and friends who encouraged me through the long hours of data collection and writing. I also wa nt to thank all the individuals who I worked. This has been an incredible experience, from start to finish. Reaching what is hopefully the commencement of my r esearch experience, I now see that investigating research questions produces as many questions as it does answers.
5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ ............... 4 LIST OF TABLES ................................ ................................ ................................ ........................... 6 LIST OF FIGURES ................................ ................................ ................................ ......................... 7 ABSTRACT ................................ ................................ ................................ ................................ ..... 8 CHAPTER 1 INTRODU CTION ................................ ................................ ................................ .................. 10 Introduction to Semantic Priming ................................ ................................ ........................... 10 Noun Noun Pair Semantic Priming in Older Adults ................................ .............................. 12 Semantic Priming in Noun Verb Relationships ................................ ................................ ..... 19 2 METHOD ................................ ................................ ................................ ............................... 24 Participants ................................ ................................ ................................ ............................. 24 Stimuli ................................ ................................ ................................ ................................ ..... 25 Procedures ................................ ................................ ................................ ............................... 26 3 RESULTS ................................ ................................ ................................ ............................... 29 Data Analysis ................................ ................................ ................................ .......................... 29 Participant Analysis ................................ ................................ ................................ ................ 29 Item Analysis ................................ ................................ ................................ .......................... 30 4 DISCUSSION ................................ ................................ ................................ ......................... 34 APPENDIX A VERB RELATED AGENT PAIRS (WITH RELATEDNESS RATINGS) AND VERB UNRELATED AGENT PAIRS ................................ ................................ ............................. 39 B VE RB RELATED PATIENT PAIRS (WITH RELATEDNESS RATINGS) AND VERB UNRELATED PATIENT PAIRS ................................ ................................ .............. 40 LIST OF REFERENCES ................................ ................................ ................................ ............... 41 BIOGRAPHICAL SKETC H ................................ ................................ ................................ ......... 44
6 LIST OF TABLES Table page 2 1 Participant Demographic Information ................................ ................................ ............... 28 3 1 Reacti on Time Data for Participants ................................ ................................ .................. 31 3 2 Reaction Time Data for Items ................................ ................................ ............................ 31 3 3 Summary of Statistical Analyses ................................ ................................ ....................... 32
7 LIST OF FIGURES Figure page 3 1 Reaction times for each group, organized by item. ................................ ............................ 33
8 Abstract of Thesis Presented to the Graduate Sc hool of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Arts VERB AND THEMATIC ROLES PRIMING IN YOUNGER AND OLDER ADULTS: IMPLICATIONS FOR SEMANTIC PROCESSING By Sara E. Mizrahi May 2009 Ch air: Lisa A. Edmonds Major: Communication Sciences and Disorders Verbs are central to the semantics and syntax of a sentence via their relationship with their arguments. Online priming studies in young adults have found that verbs (e.g., arrest ) provide i mmediate access to typical agents (e.g., policeman ) and patients (e.g., criminal ) by generating expectancies from a verb and its related thematic roles and vice versa. This relationship links lexical semantic knowledge to event memory. These findings sug gest a neural co activation whenever either a verb or its closely related noun is selected in a relevant context. Using a lexical decision task with a short stimulus onset asynchrony (250ms), this study aims to 1) replicate agent and patient priming of ve rbs in younger adults, 2) investigate agent and patient priming of verbs in older adults (not previously done), and 3) incorporate adaptations of the procedure in order to test adults with aphasia in future studies. Consistent with our predictions, partic ipants showed significantly faster reaction times for related agent verb ( thief/stealing ) and patient verb ( coffee/brewing ) pairs than for unrelated agent verb ( thief/winning ) and patient verb ( pizza/brewing ) pairs by participants and items. Reaction time s were significantly faster for younger adults than older adults. These findings replicate previous younger adult results and demonstrate the maintenance of automatic thematic role verb processing in older adults. These
9 findings provide a foundation for t reating acquired neurogenic disorders characterized by changes in semantic processing.
10 CHAPTER 1 INTRODUCTION Introduction to Semantic Priming Semantic priming studies generally examine if participants respond faster when a target word is accompanied by compared to a target that is not related to the prime (Neely, 1990). Semantic priming effects (i.e., faster reaction time for related items) depend on semantic memory, requiring a meanin gful relationship between target and prime (Giffard, Desgranges, & Eustache, 2005). Priming paradigms can be manipulated so they can activate either automatic or attentional levels of semantic processing? (Del Toro, 2000; Myerson, Ferraro, Hale, & Lima, 19 92). Automatic processing assumes semantic relationships are processed at an automatic or implicit level, whereas attentional processing requires more cognitive effort, attention, and executive resources (Myerson et al., 1992). Many studies have different iated between levels of processing by manipulating the onset of presentation of stimuli (stimulus onset asynchrony (SOA); i.e. temporal distance between target and prime) and have identified different levels of consciousness associated with short and long lexical decision paradigm (LDT), where participants decide whether a string of letters represents a legal word or not, to measure semantic priming trends (Myerson et al., 1992). Two main mechani sms have offered explanations for single word priming trends: spreading activation and expectancy generation (Neely, 1990). The spreading activation theory proposes that information is stored in memory at specific nodes and presenting semantically related information initiates the spread of activation between nodes. For example, the word dog may be represented at one node, which may in turn activate or be activated by related features (paw, tail) or categories (animal, poodle). In automatic priming tasks this manifests in
11 participants responding to semantically related words faster than unrelated word pairs. Another suggestion for such results has been explained by the expectancy model, which has been described in sentence and single word processing ( Mc Rae, Hare, Elman, and Ferretti, 2005). According to the model, individuals make predictions about an item most likely to follow a prime. In sentence comprehension, this implies expectations between noun and verb phrases based on general event knowledge ( individuals predict a girl will ride a carousel more frequently than a motorbike) On the single word level, one might also build an expectation that apple will follow the presentation of fruit This theory also has been broken into two types of expectan cies: implicit and explicit expectancy. Implicit expectancy generation occurs at an automatic level and has been used to describe normal sentence processing as well as automatic priming results (e.g., semantic priming paradigms with short SOA). Explicit expectancy generation, alternately, involves conscious strategizing and is often used in attentional noun noun priming paradigms (e.g., investigator instructs participant to decide if the prime and target are related). Spreading activation and expectancy models both seek to validate the pattern of semantic processing as evidenced by priming studies. Semantic priming is of interest because it provides insight into semantic organization and processing in normal adults (i.e., those without pathological neuro logical changes) as well as in individuals with a variety of neurological changes due to neurodegenerative disease such as damage due to stroke and traumatic brain injury. Within the healthy adults, investigations further examine similarities and differences in younger and older subgroups from which information about semantic memory in normal aging can be inferred. Understanding semantic memory in older adults is vit al to differentiating normal aging from pathological changes and so that normal
12 older groups can be compared to neurological patients to understand better the effects of neurological changes and damage. Understanding semantic changes in patients also allow s researchers and clinicians to diagnose more accurately and to develop targeted behavioral treatment paradigms. Noun Noun Pair Semantic Priming in Older Adults The majority of research conducted in older adults has been in noun pair relationships. Noun p airs have been classified as vertically related or horizontally related (Ober, Vinogradov, & Shenaut, 1995). Vertically related nouns refer to superordinate subordinate semantic relationships, which are hierarchically related within a category. These may i nclude category exemplar ( animal dog ) relationships or attribute feature ( zebra stripe ) relationships. Horizontally related nouns, on the other hand, are intracategorical, serving as coordinate co members of a category ( dog cat ). Noun relationships are not always of equal association, as they may be combinations of atypical typical ( penguin robin ), atypical atypical ( penguin ostrich ), typical typical ( robin cardinal ), and typical atypical ( robin penguin ) pairs (Ober et al., 1995). Overall, the results of the noun noun semantic priming studies have shown that older adults are consistently slower in their reaction times as compared to younger adults (e.g., Laver & Burke, 1993; Myerson et al., 1992; Myerson, Hale, Chen, & Lawrence, 1997). Although older adu lts generally show the same priming effects that younger adults do, some studies show that the priming effects for older adults are actually greater than those observed for younger adults (e.g., Laver & Burke, 1993). A brief discussion of the findings, int erpretations, and theoretical implications for the slowing and inconsistent priming effects literature follows. Two general explanations for slower rates of reaction for older adults have been proposed based on semantic priming findings. One explanation po sits a general cognitive slowing in the lexical domain and the other argues for process specific slowing, or visual processing slowing
13 (Laver & Burke, 1993). While the issue is not resolved, it appears that there is more support for the lexical domain slow ing hypothesis based on meta analyses of a number of semantic priming studies (Balota & Ferraro, 1992; Lima, Hale, & Myerson, 1991; Madden, 1989; Madden, Pierce, & Allen, 1993; Nebes & Madden, 1988; Salthouse, 1985) where researchers found a proportional r elationship of increased reaction times with slopes ranging from 1.3 to 1.5 when plotting older single, global factor of speed reduction in older adults (Myers on et al., 1997). As the global rate reduction theory has developed through the years, proponents of the general cognitive slowing hypothesis have made distinctions between degrees of slowing within lexical and non lexical domains (Lima et al., 1991). W ithin more recent studies, theories have stated that despite these differential degrees of slowing (i.e. visuospatial information is processed domains (Myerson, Hal e, Zheng, Jenkins, & Widaman, 2003). Within the lexical domain, specifically, various meta analyses have identified a general slowing factor of approximately 1.5 among older adults processing verbal information. Hale & Myerson (1995) specified that this factor is best realized when there is a fifty year gap between younger populations (cutoff in mid In an attempt to investigate the mechanism for slowing in older adults directly, Myerson et al. (1997) conducted three sema ntic priming studies on younger and older adults and found that older adults were 1.3 times slower than young adults across all three studies. In addition, they examined the nature of the slowing by comparing within subject results on lexical tasks that re quired more (double lexical decision task, for which lexical decisions are made for a pair of words) and less (category membership) processing time than the lexical decision task. Results
14 revealed consistent slopes across tasks, regardless of processing s peed. These findings support general lexical slowing. Madden et al. (1993) also defended a generalized, age related slowing based on results in a series of four experiments. Their description of the generalized slowing hypothesis, however, did not diffe rentiate between lexical and non lexical domains, as previous studies had (e.g., Lima et al., 1991; Myerson et al., 1992). Rather, they focused on the lexical domain. In their study, Madden et al. (1993) varied the time course of semantic priming over a series of lexical decision and pronunciation tasks, finding that results of age related slowing across time course conditions and tasks were somewhat variable across experiments. Upon regression analysis, however, mean 8, which was consistent with that of most past meta analyses in length of SOA) and prime type variables (e.g., related, unrelated, or neutral). (Madden et al., 1993). Madden et al. (1993) also explored semantic priming effects across age groups. Priming effects resulted in a generalized slowing function of less than 1.0. These results fall in line with the task dependent slowing hypothesis rather than generalized lexical slowing (Laver & Burke, 1993). Hale & Myerson (1995) proposed that the inconsistency of priming effect results with the generalized slowing hy pothesis may have been related to small data set, reliability, and effect size differences relative to past meta analyses. While Madden et al. (1993) generally supported the generalized cognitive slowing hypothesis, elements of their results point to inco nsistent age related differences. Likewise, others have pointed to different age related factors.
15 analysis did not support the general lexical slowing hypothesis supported in several other meta analyses. The authors evaluated 1 5 studies and 49 priming conditions with a regression analysis for priming effects and absolute mean. In both cases, the slopes were not different from 1.0. The authors concluded from these findings that the ality specific (e.g., orthographic versus auditory) rather than a generalized lexical slowing process. Such conclusions are based on a variety of possible explanations that differentiate between the degrees of slowing of various cognitive processes in agi Myerson (1995) responded to these findings and argued that if analyzed with a few additional sl owing. Their work applied such considerations (maintaining constant age difference and these changes, the regression analyses for response times and semantic pr iming effects revealed a slope consistent with other meta analyses (1.5), further supporting the lexical slowing hypothesis (Hale & Myerson, 1995). In addition to reduced speed, differences in semantic priming effects may be another age related factor in o lder adults; however, the findings across studies have not been consistent. Some meta analyses have found that there is no significant difference in the priming effects in older adults as compared to younger adults, despite overall slower reaction times (e .g., Myerson et al., 1992; Myerson et al., 1997), while others have found larger priming effects (i.e., longer reaction times for related vs. unrelated prime target pairs) (e.g., Laver & Burke, 1993). Since most evidence suggests that the semantic system d oes not degrade with normal aging (Giffard et al., 2005), processes of semantic priming are not expected to differ in older adults. Myerson et al.
16 (1992) described the correspondence axiom a hypothesis by Cerella (1990) that attempts to explain the nature of priming effects in aging. Specifically, it suggests that the product rather than the process of priming is measured in semantic priming. With this assumption, the process of priming in older adults corresponds to that in younger adults. In a lexical de cision paradigm, following an unrelated prime. Conversely, this increased processing time is not needed to process the related prime. Since the additional proce ssing time required for older adults is greater than that for younger adults, the slowed rate of processing in older adults appears to manifest in increased priming effects, but truly only represents the additional processing time in which one engages in a n unrelated context (Myerson et al., 1992). Other researchers have attempted to explain increased priming effects in older adults as a function of changes in processing. Giffard, Desgranges, and Kerrouche (2003) proposed that increased priming effects are at least in part due to changes in attentional processes, despite a common perspective that in automatic priming, attentional differences are not relevant. Giffard et al. (2003), found that even in automatic semantic priming conditions, attentional diffe rences impacted variability and slowed processing in older adults. These authors also characterized hyperpriming Giffard et al. (2003) compared the trends of hyperpriming in normal aging to those among adults with Alzheim study, these researchers controlled for attention and cognitive slowing to investigate priming effects and the nature of semantic memory in these two groups. Based on their findings, Giffard et al. (2003) concluded that increase d semantic priming effects were a characteristic of general slowing in normal aging, in which semantic memory is intact. Among adults with AD, however,
17 they attributed the hyperpriming phenomenon to deficits in semantic memory. These findings further suppo rt the integrity of the semantic system outlined in aging literature. Laver and Burke (1993) put forth two additional explanations for increased priming effects in older adults. Their main argument relates to the interactive compensatory framework (see Nee ly, 1990), where there is an inverse relationship between semantic activation from semantic context (for spreading activation or attentional expectancy mechanisms) and sensory processing (e.g., word recognition), so that when semantic activation increases during semantic priming, there is a reduction in visual processing requirements for word recognition. According to the authors, since visual perception slows with age, there is a greater effect of the semantic activation, thus increased priming effects. An alternative explanation Laver and Burke (1993) proposed is the transmission deficit hypothesis which holds that the transmission of priming is slowed in old age. The slowing is compensated for by enhanced connections between nodes as a result of more ex perience in life. Accordingly, this results in increased priming effects for older adults. analysis results that showed increased priming effects. Hale and Myerson (1995) reviewed Laver a data set used for effect size and noted that the same problem data sets used by Laver and Burke (1993) for RT analysis were used for semantic priming effect analyses. They also acknowledged, as past researchers had, that the analysis of the dif ference provides half of the (Hale & Myerson, 1995; Myerson et al., 1992; Myerson et al., 1997). In attempt to reevaluate their results, Hale and Myerson (199 5) compared results of regression analyses with and without the questionable data sets. The results of the modified analysis revealed a slope of 1.32 as
18 of 1. 5 supported by other meta analyses. The slowing factor in their analysis was the same for that processing differences are stable across a variety of tasks. Al so, when the amount of facilitation (SPE) was compared between groups, no difference was found between effect sizes. among older adults. These conclusions contrad ict those of Laver and Burke (1993), who included the questionable outlier data sets in their analyses. These modified results are consistent with Myerson et al. (1992) and also coincide with the general lexical slowing hypothesis. The extensive researc h exploring semantic processing in older adults via noun noun semantic priming has yielded significant findings about aging patterns. Generally, older adults have demonstrated similar priming patterns to younger adults, showing significant facilitation fo r semantically related stimuli (Hale & Myerson, 1995; Myerson et al., 1992; Myerson et al., 1997; Laver & Burke, 1993; Madden et al., 1993). While the priming pattern appears to remain intact, these researchers have also identified a slower rate of proces sing with aging. The majority of literature has characterized these reductions in speed as a function of generalized lexical slowing, consistent across all lexical processing tasks (Myerson et al., 1992; Myerson et al., 1997; Lima et al., 1991; Hale & Mye rson, 1995). Despite the slower rates of processing, evidence has generally pointed to similar semantic priming effect sizes in older adults and younger adults (Myerson et al., 1992; Myerson et al., 1997). These findings have provided an important founda tion for related single word semantic processing questions.
19 Semantic Priming in Noun Verb Relationships Though most single word priming paradigms in older adults have explored automatic semantic processing through noun noun relationships, Hagoort (1993) va ried grammatical class in a priming paradigm with older adults. In his work, Hagoort (1993) compared participants with decision task. The task consisted of a two p rime sequence in which the second prime was a homographic homophone with at least two unrelated meanings (e.g., bank ). The prime pairs included mostly noun noun (e.g., ball ) and noun verb (e.g., bark ) ambiguities. Additionally, there were four priming co nditions presented, in which the prime target relationships were varied. These conditions included concordant pairs (i.e., second prime related to first prime and target by same meaning: beer hangover DRINK ), discordant pairs (i.e., second prime related to first prime and target in different ways: cat hangover DRINK ), neutral pairs (i.e., second prime related to target but not to first prime: piano hangover DRINK ), and unrelated pairs (i.e., all three words were unrelated: cat piano DRINK ). The results fo r the control subjects indicated a main effect of Priming Condition and an interaction between Type of Ambiguity and Priming Condition. Furthermore, older adult controls showed facilitation for concordant, discordant, and neutral conditions for noun noun items. For noun verb items, however, they only demonstrated facilitation for concordant and neutral conditions, indicating more selective activation of the appropriate meanings for noun verb pairs than for noun noun ambiguous pairs. Hagoort explained thi s phenomenon as a result of two types of representations being accessed in noun verb ambiguities (i.e., attention to meaning and form class). When the same experiment was run on a group of young adults, they showed the same selective activation for noun n oun pairs as they did for noun verb pairs. Hagoort (1993) postulated that the discrepancy in findings across age groups may be attributed to
20 attentional differences that the change in grammatical class requires in older adults relative to younger adults. T semantic processing in normal adults, he used the noun verb relationship to compare this processing to so investigated lexical semantic processing via the noun verb relationship. According to the thematic role model, verbs and nouns place constraints on one another based on expectancies (McRae et al., 2005; Ferretti, McRae, & Hatherell, 2001; McRae, Spivey Knowlton, & Tanenhaus, 1998). Events are constrained by verbs, which are further constrained by related nouns (McRae, Ferretti, Amyote, 1997). The tendency for verbs to co occur in events with particular nouns constrains the meaning initially associated with the word pairs. These expectancies are the result of general event knowledge (e.g. experience with accusing guides typically associated people who accuse and of what they are accused) (McRae et al., 2005). Studying the noun verb relationship in sing le word priming paradigms can provide insight into the interaction between lexical and conceptual knowledge. A number of priming studies have shown that a verb makes information available about its typical agents (i.e., doer of the action) and patients (i. e., receiver of the action). In four separate experiments with undergraduate adult participants, Ferretti et al. (2001) paired transitive verbs with related agents (e.g., arresting/policeman ), patients (e.g., arresting/criminal ), instruments (e.g., cutting /scissors ), and locations (e.g., skating/arena ) in addition to pairs that were not related (e.g., arresting/parent ). A group of normal, young subjects read the verb (prime) silently, and then made a semantic (animacy) decision for each target (noun) (i.e., decided whether the noun was animate or not). Reaction times for decision of animacy were recorded after
21 presentation of the noun. The results showed significantly faster reaction times when the prime (verb) was paired with typical agents (e.g., policeman after arresting ), patients (e.g., criminal after arresting ), and instruments (e.g., scissors after cutting ) than when the verbs were paired with non typical agents, patients, and instruments. Typical locations (e.g., arena ) for a verb (e.g., skating ) did not show significantly faster reaction times than locations not typical for a particular verb (e.g., danced/court ). The researchers suggested that the lack of priming may be explained by the insufficiency of a location independently to prime a verb (e.g., locations are not well defined and actions may take place across various locations) McRae et al. (2005) examined whether the reverse trend would be true, i.e., if thematic roles that are typically associated with a verb would prime the verb. In this stu dy young undergraduate participants saw the prime (noun) and silently read the target (verb), completing a pronunciation or a naming task. As in Ferretti et al. (2001), they investigated typical agents (e.g., nun/praying ), patients (e.g., dice/rolled ), ins truments (e.g., shovel/digging ), and locations (e.g., arena/skating ) as well as non typical noun/verb pairs and found that all of the nouns (including locations) primed related verbs (i.e., had significantly faster reaction times than noun primes paired wi th unrelated verbs). McRae et al. (2005) and Ferretti et al. (2001) concluded that there appears to be neural co activation whenever either a verb or its closely related noun argument is selected in a relevant context. The implication is that memory is st ructured so that when a verb is activated a generalized situation model is also activated. Additionally, event memory appears to be organized so that nouns activate the event class in which they typically play a role (Lancaster & Barsalou, 1997). For exam ple, an event (e.g., driving) can be accessed via participatory nouns (e.g., chauffer, limousine). Thus verbs fit into a generalized schema and are surrounded by
22 related nouns, which are accessed directly from event memory (Ferretti et al., 2001). Genera lized situations, just like individual words, can be ordered hierarchically, denoting different levels of representation and thus different degrees of detailed memories. These conclusions, based on the findings of McRae et al. (2005) and Ferretti et al. ( 2001), can only be extended to young adults, since that is the population they studied. Whether these generalized verb schemas respond similarly in normal aging has yet to be examined. However, semantic priming patterns in older adults have been quite exte nsively researched, but the primary semantic relationship explored has been noun pair combinations. Similar to McRae et al. (2005) and Ferretti et al., (2001), we investigate verb thematic role (verb agent, agent verb, verb patient, and patient verb) prim ing in younger adults and extend our investigation to older adults. We replicated previous methodology in young adults with a different priming paradigm (lexical decision versus animacy and naming). The investigation of older adults aims to discover wheth er noun verb priming patterns in young adults are maintained in normal aging since the majority of what is known about older adult semantic processing is derived from work involving noun noun relationships. As suggested by McRae (2005), expectations of ve rb noun processing may not directly map onto models of noun noun processing. The relationship between verbs and their thematic roles may be more dependent on syntactic cues, even when removed from the context of a sentence (Ferretti et al., 2001). Accord ingly, these authors proposed that verb thematic role pairs are representations that often co occur in specific language and events, while noun noun pairs may not. Regarding expectations for older adult semantic processing, the difference in nature of int eractions between noun noun and noun verb relationships is important to identify at the outset of the current study. An additional reason for understanding the priming patterns in older adults is to provide a
23 foundation upon which researchers of acquired neurogenic disorders that affect, at least in part, example, the findings of McRae, Ferretti, and colleagues have already been directly applied as theoretical suppor t for a treatment paradigm for individuals with aphasia (Edmonds, Nadeau, & Kiran, in press). This treatment, called Verb Network Strengthening Treatment (VNeST), presumes that there is bidirectional activation of verbs and their related thematic roles and capitalizes on this presumption by promoting activation and retrieval of agent verb patient networks to aid word retrieval in sentence contexts. However, since the single word online priming studies of McRae, Ferretti and colleagues were only conducted wi th young populations, there is limited empirical evidence to suggest that the robust bidirectional priming they reported persists in older adults. Thus, the current study seeks to both replicate findings of past verb thematic role priming studies in younge r adults and to further investigate priming patterns in older adults. Our specific questions and predictions are as follows: Is the reaction time for related noun verb pairs faster than for unrelated noun verb pairs in younger adults? o It is expected tha t the younger adult groups will replicate the findings of McRae, Hare, Elman, & Ferretti (2005) and Ferretti, McRae, & Hatherell (2001) and show significantly faster reaction times for related noun verb pairs than unrelated noun verb pairs. Is the same pri ming pattern for younger adults (YA) seen in older adults (OA)? o It is expected that the same priming pattern will be observed for the older adult group, but that the older group will exhibit significantly slower reaction times (Myerson, Hale, Jing, & Lawr ence, 1997).
24 CHAPTER 2 METHOD Participants Forty five younger adults ( M = 20.4 years, range 18 to 22) and forty older adults ( M = 73.6 years, range 60 to 91) participated in the study. Twenty saw pairs of words in the order noun verb for both agent verb (e.g., pilot flying ) and patient verb (e.g., flying airplane ) conditions (details to follow). Twenty and twenty noun). Statis tical analyses revealed no difference for order of presentation (i.e. noun to verb or verb to noun) for any condition ( t (83) = 1.143, p = .255 for related agents; t (83) = 0.988, p = .326 for unrelated agents; t (83) = 0.465, p = .643 for related patients; t (83) = 0.318, p = .751 for unrelated patients), so participants were collapsed. Younger adults were recruited at the University of Florida and received course credit for their participation. Older adults were recruited throughout Gainesville, Florida and received $10/hour for their participation. Both older and younger adults completed at least 12 years of education. See Table 2 1 for participant demographic information. All participants were right handed, native English speakers who reported no history o f neurological diagnosis or injury, alcohol or drug addiction, depression, or learning disorder based on their responses to a questionnaire. Additionally, older adults were screened for cognitive and linguistic deficits using the Cognitive Linguistic Quick Test (Helm Estabrooks, 2001), which has attention (e.g., symbol cancellation tasks and symbol trails), executive functioning (e.g., mazes, clock drawing), memory (e.g., story retell, design recall), visuospatial (e.g., symbol trails, design generation), a nd language (e.g., confrontational naming, generative naming) subtests. Semantic processing was screened using the Pyramids and Palm Trees (Howard & Patterson, 1992) for noun processing and Kissing and Dancing (Bak & Hodges,
25 2003) for verb processing. For each of these tests, a triad of words or pictures is shown to the participant with one word on top (e.g., stethoscope ) and two on the bottom (e.g ., tongue heart ). The participants are required to point to the word or picture on the bottom that goes best w ith the word on the top. Participants were tested with words since the priming study consisted of making judgments about written words. All participants scored within normal limits on all subtests of the CLQT according to the standard scoring procedures. F urther, all older adults scored a minimum of 90.4% on the Pyramids and Palmtrees and Kissing and Dancing tests. See Table 2 1 for participant information. Two younger adults and two older adults who were tested were not included in the study. One of the younger adults failed to comply with task instructions and the other younger adult was multi lingual. Both of the older adults demonstrated mild moderate deficits on the language and attention subtests of the CLQT. Stimuli There were two conditions for eac h experiment, an agent condition and a patient condition. For each condition, five sets of word pairs were created. Set 1 consisted of related noun (either agent or patient) verb pairs, and Set 2 consisted of unrelated noun verb pairs. The remaining three sets were noun verb pair foils and pairs consisting of non word targets. Thus, the ratio of target pairs to foil pairs was 2:3. In order to develop the noun verb pairs of interest, 13 University of Florida undergraduates completed two questionnaires (Fer retti et al., 2001). The questionnaires required participants to rate how common it is for someone to perform an action (agent pairs) and for something to be the receiver the action (patient pairs) on a scale of 1 (not common) to 7 (very common). Thirty on e related agent verb pairs (e.g., thief/stealing ) ( M = 6.73, SD = 0.14) and 26 related patient verb pairs ( M = 6.67, SD = 0.19) were used. Several pairs were exact duplicates of McRae et al.
26 (2005) and Ferretti et al. (2001), while others were developed i ndependently (e.g., pilot/fly ). Unrelated pairs were formed by shuffling words used in sets of related pairs (e.g., pilot/hiring ). Filler sets were created from additional verbs (e.g., button/scrubbing ) and nonword pairs (e.g., barber/prafing ). Nonwords w ere of equal length to the verbs in the target (i.e., related and unrelated) words and all were phonotactically legal in English. All verbs, both real and nonwords, were presented with present progressive inflection (i.e., ing ending). See Appendix A and B for details. The experiment was developed on DirectRT software (Empirisoft, 2004) and run on a Dell computer with a 17 inch monitor. In each trial, participants saw a focal attention fixation point (#) for 250 ms, followed by a prime (noun or verb) for 200 ms, a mask (&&&&&&&&&) for 50 ms, and last, the target (verb or noun), until a lexical decision was made. The inter stimulus level (ISI) was 250 ms and the inter trial interval (ITI) was 1500 ms. The durations of stimuli presentation as well as the IS I and ITI durations were all consistent with McRae et al. (experiment 1, 2005) and Ferretti et al (2001). Procedures In order to compare young adult results of this study to those of McRae et al. (2005) and e procedures of those studies was made. However, some modifications were made to allow for the eventual implementation of the experiment on individuals with aphasia. Modifications included the use of a lexical decision task (LDT) in place of an oral readi ng task (McRae et. al., 2005) or animacy decision task (Ferretti et al.), since both of these tasks were expected to be more difficult for persons with aphasia than a lexical decision task. LDT has been used previously in studies involving persons with ap hasia (Hagoort, 1993). Past research has also suggested that LDT performance has been found to be minimally dependent on strategy (Myerson et al., 1997). This limits variability between participant
27 responses and more directly attributes duration of proces s to speed of semantic processing. and disordered populations (Myerson et al. 1997; Giffard et al., 2005). Additionally, all participants were instructed to use t heir left hand to complete the computerized tasks for future implementation on persons with aphasia who often have hemiparesis of their right hand and arm (Kiran & Thompson, 2003). The present study was comprised of two phases. In phase 1, the noun (prime ) was followed by a related or unrelated verb pair (target). In phase 2, the verb (prime) was followed by a related or unrelated noun pair (target). The related and unrelated pairs were the same in both phases: only the order of presentation was different Participants were asked to make a lexical decision about words presented in a random order. Participants received directions on the screen, which were read to them before each practice session and trial. Instructions stated that they were to read the fir st word silently to themselves and for the second, decide whether or not it is a real word. If sessions and both test conditions (agent verb and patient verb) and expressed understanding of the task. The order of conditio ns presented was counterbalanced across participants.
28 Table 2 1. Participant Demographic Information Group (by age) Age (years) Education (years) CLQT Pyramids and Palmtrees Kissing and Dancing YA (N = 45) 20.4 14.2 N/A N/A N/A OA (N = 40) 73.6 15.1 3.93 (0.14)* 50.08 (1.53)** 50.50 (1.34)*** Based on composite scores, a score of >3.5 is considered within normal limits (WNL). ** > 90% is considered WNL (Howard & Patterson, 1992). ***> 90% is WNL (Bak & Hodges, 2003).
29 CHAPTER 3 RESULTS Data Ana lysis All reaction times were recorded by the DirectRT software (Empirisoft, 2004). Lexical decision reaction times greater than three standard deviations above the mean for participants and items were replaced by the value for three standard deviations ab ove and below the mean (Ferretti et al., 2001). For the noun verb condition, the percentage of responses that were > 3 SD was less than 2.0% for both age groups (range = 1.2 1.8%). For the verb noun condition, the percentage of responses > 3 SD was les s than 2.5% for both older and younger adults (range = 1.36 2.19%). When errors were made in lexical decisions, reaction times were replaced by the mean value for that data set (participant or item). See Ferretti et al. (2001) and McRae et al. (2005). For phase 1, accuracy for both age groups was greater than 98% (range = 98.25 99.82%). Participant Analysis Results of an independent t test showed that order of prese ntation of stimuli (noun verb, verb noun) was not a factor in reaction times across participants for any condition (related agents: t (83) = 1.146, p = .255; unrelated agents: t (83) = .988, p = .326; related patients: t (83) = .465, p = .643; unrelated patie nts: t (83) = .318, p = .751), so all participants were grouped together for the participant analysis. This was advantageous because p ast research has identified increased variability among response times of their older adult sample (Myerson et al., 1997), and including more older adults for adequate statistical power is necessary. See Table 3 1 and 3 2 for raw reaction times for participants and items. There was a significant difference in reaction times between age groups (F(1, 83) = 46.096, p < .001), with the younger adult group responding significantly faster than the older adult group.
30 A repeated measures ANOVA revealed a main effect for relatedness (F(1, 83) = 5.386, p = .023) within participants, with unrelated items being responded to slower than related items. There was no relatedness/thematic role interaction (F(1, 83) = .867, p = .355), indicating that reaction time differences were not dependent on whether the observed stimuli were agents verb or patient verb pairs. See Table 3 3 for a summary of statistics and Figure 3 1 for a graphic depiction of reaction time trends by participant for each group. Item Analysis A repeated measures ANOVA revealed a significant difference in reaction times within items (F(1, 4843) = 47.328, p < .001) and a si gnificant difference in item reaction time across age groups (F(1, 4843) = 1302.614, p < .001). To answer the question whether reaction times for items for each condition within each group were different, paired t tests were conducted. There was a signif icant difference for the agent ( t (1394) = 3.946), p < .001) and patient ( t (1169) = 6.5, p < .001) conditions in younger adults, with related noun verb pairs being significantly faster than unrelated noun verb pairs. There was also a significant differenc e in both conditions in the older adult group (agents: t (1239) = 2.101, p = .036; patients: t (1039) = 4.248, p = .000), with significantly faster reaction times for related noun verb pairs than unrelated noun verb pairs. See Table 3 3 for a summary of s tatistics and Figure 3 2 for a graphic depiction of reaction time trends by item for each group.
31 Table 3 1. Reaction Time Data for Participants Dependent Measure Agents M SD Patients M SD Younger Adult Response Latency Unrelated 678.54 151.10 663.72 138.42 Related 647.20 143.20 622.33 136.72 Facilitation 31.34 41.39 Older Adult Response Latency Unrelated 1043.73 377.09 1007.08 350.46 Related 999.76 282.28 947.13 307.16 Facilit ation 43.97 59.95 Table 3 2. Reaction Time Data for Items Dependent Measure Agents M SEM SD Patients M SEM SD Younger Adult Response Latency Unrelated 676.58 6.19 231.30 667.36 6.91 236.21 Related 647.65 6.36 237.51 62 1.24 6.37 217.71 Facilitation 28.93 46.12 Older Adult Response Latency Unrelated 1042.39 18.38 647.16 1009.75 16.64 536.68 Related 1004.60 12.89 454.01 949.43 13.28 428.25 Facilitation 37.79 60.32
32 Table 3 3. Summary of Statistical Analyses Comparisons Test Condition Results Significance PARTICIPANT ANALYSIS Difference in RT across groups Repeated Measures ANOVA YA/OA F(1, 83) = 46.096, p < .001 Yes Difference in related vs. unrela ted pairs Repeated Measures ANOVA By Participant F(1, 83) = 5.386, p = .023 Yes Relatedness by Thematic Role (agent/patient) Repeated Measures ANOVA By Participant F(1, 83) = .867, p = .355 No ITEM ANALYSIS Difference in related vs. unrelated pairs Repeated Measures ANOVA By Item F(1, 83) = 47.328, p < .001 Yes Group by Relatedness by Thematic Role (agent/patient) t test YA Ag YA Pt OA Ag OA Pt t (1394) = 3.946, p < .001 t (1169) = 6.5, p < .001 t (123 9) = 2.101, p = .036 t (1039) = 4.248, p < 001 Yes Yes Yes Yes YA: Younger adult; OA: Older adult; Ag: Agent; Pt: Patient; Part: Participant
33 Figure 3 1. Reaction times for each group, organized by item. The standard error of the mean is indicated for each condition and group.
34 CHAP TER 4 DISCUSSION The current study investigated bi directional priming in verbs and their thematic roles in the context of normal language in younger adults and older adults. As predicted, young adult participants demonstrated significantly faster reactio n times for related noun verb and verb noun pairs than for unrelated pairs when nouns were agents and patients. T hese results are consistent with semantic priming effects previously found in young adult populations in McRae et al. (2005) and Ferretti et a l. (2001). The existence of the semantic priming trend among young protocol, providing evidence that the trend is not dependent on a particular task, handedness or participant. As predicted, the older adult group showed bidirectional semantic priming effects for noun verb pairs across all conditions. Thus, as with noun noun semantic priming studies in older adults, noun verb pairs also exhibit semantic primin g patterns similar to younger adults (Laver & Burke, 1993; Myerson et al. 1992; Myerson et al., 1997; Madden et al., 1993). Few studies have explored noun verb relationships within older adult populations. However, those that have have identified older a dults without disorders as demonstrating strong semantic priming effects. This pattern is most drastically emphasized in studies comparing priming effects of normal older adults as control subjects against older adult populations with a variety of neurolo gical disorders (Hagoort, 1993). Using lexical decision tasks, these studies identified that older adults maintain the semantic priming pattern of younger adults at the automatic level. Older adult research in the area of automatic semantic priming has generally yielded two main patterns. The first finding of slower reaction times among the older adult population as compared to younger adults has been identified in this study. The question regarding the nature
35 of this slowing trend, as generalized or process specific, was neither asked nor directly addressed in the present study. While literature that supports the current work generally asserts the general lexical slowing argument, the current research does not support one theory over another. Rat her it focuses on the pattern of semantic processing that does exist within the older adult population (Laver & Burke, 1993; Myerson et al., 1997; Myerson et al., 1992; Hale & Myerson, 1995). This pattern among the older adults generally parallels the eff ect of relatedness in younger adults. Another widespread trend among the aging semantic priming literature is the presence of a larger priming effect among older adults than younger adults (Giffard et al., 2003). This has often been described as a pheno menon that manifests as a result of the increased processing latency among the older adults. The results of the present study do not suggest that the priming effect among older adults is greater than the priming effect among younger adults. Raw latency t imes demonstrate more facilitation for older adults than for younger adults in both agent and patient conditions for participants and item. This difference does not appear significant (approx. 12.63 ms difference for agents and 18.56 ms difference for pat ients by participant; 8.86 ms for agents and 14.20 ms for patients by item). Additionally, the difference in degree of the semantic ticipant. This suggests that the difference in facilitation may be adults. The older adult findings indicate that there is an automatic co activation of rel ated verbs/thematic roles that is maintained in normal aging. The results of older adult work represent a wide variety of ages (adults from 60 91), which together demonstrate the same pattern of semantic priming that young adults exhibited. These results differentiate semantic
36 processing, which is maintained in normal aging, from a generalized slowing, noted in consistently slower reaction times among older adults than younger adults. The literature on semantic priming in older adults also contrasts norm al semantic priming trends with the disease and semantic access deficits in aphasia (Giffard et al., 2003; Hagoort, 1993). Future examination of noun verb relatio nships in these clinical populations is warranted. on verb thematic role semantic priming contextualizes the proposed mechanism of expectancy generation. In their work, McRae et al. (2005) used the expectancy model to explain their findings. More specifically, they stated that their findings can only be described by expectancy generation that relies on lexical and world knowledge (McRae et al., 2005). According to McRae et al. (2005), this mechanism explains the specific semantic relationship between verbs and their thematic roles, namely that a verb is connected to particular thematic roles by way of experiential knowledge. This knowledge is a generalized compila tion of specific encounters with words, assembled in a memory for particular events. This organization allows for more general, frequent verbs to have more thematic roles associated than more specific, less frequent expectation for related noun. McRae et al. (2005) did not only attribute the priming effects to expectancies based on event memories, but also the stimuli themselves. They suggested that the word pa irs chosen are bound by their co occurrence in real life events and thus their application to event memory. McRae et al. (2005) ventured further to assert why the results from their study cannot be explained by an alternative mechanism, spreading activat ion. As previously mentioned, many
37 automatic priming paradigms cite this model as a means of explaining noun noun priming effects. If the same model were used for noun verb relationships, it would fail to specify all of the important components of this i ntegral relationship (i.e. specific features that link a verb and its thematic role) (McRae et al., 2005). Similarly, the structure of nodal representations of noun and verb associations in the spreading activation network does not specify degree of rela tedness between specific associations. Thus, McRae et al. (2005) claimed that the nodal links are not sufficient in explaining the event representations portrayed by noun verb relationships in their study. For example, Ferretti et al. (2001) found eviden ce that use of the imperfect verb is more salient in event memory and thus has been used for priming in McRae et al. (2005) as well as the current study. The presence of voice does not even exist in the spreading activation theory, as different forms of t he word are not specified at particular nodes (McRae et al., 2005). McRae et al. (2005) furthermore asserted that even if words were located at particular nodes in the brain, priming occurs as a result of connectivity between thematic relationships rather than word associated links. Thus, in line with McRae et al. (2005) and Ferretti et al. (2001), the results of this study can be explained by expectancy generation, which are founded on general event knowledge and event memory. The methodology of the cur rent study is based on the structure of McRae et al. (2005) and Ferretti et al. (2001). Within this construct, many of the same stimuli, which were paired in accordance with event knowledge, are consistent between the studies. Those stimuli, which were a ltered or added, were rated on the same scale as previous used stimuli and were identified as being highly related by raters. Furthermore, the results of the current study are consistent with results of McRae et al. (2005) and Ferretti et al. (2001), name ly in degree and nature of relatedness (i.e. patient verb pairs generally faster than agent verb pairs). Nonetheless,
38 as McRae et al. (2005) suggested, it may be possible to incorporate some aspects of spreading activation semantic organization (i.e. noda l representations) in interpreting the neural correlates of noun verb processing, provided that the underlying mechanism is greater event knowledge. Based on the status of current literature, verb thematic role priming has been left fairly unexplored. The majority of the single word queries have focused on priming within a part of speech (i.e., noun), altering the SOA to see differences in processing effects. Another area of interest has been the area of aging, which has also been primarily explored throu gh noun noun paradigms. This study confirms previous hypotheses that a verb is central to the organization of event structure (McRae et al., 2005). Within the context of a sentence, a verb may form the foundation as well. Semantic relationships between a verb and its arguments are structured around the function of the verb. The stability of the semantic system through aging proposes that this noun verb relationship remains a strong foundation in semantic processing throughout adulthood. The current stu dy bridges the lines between noun verb semantic processing and semantic processing in aging to gain a greater understanding of the function of these concepts within normal language processing. One direction in which the researchers have shown interest is expanding the current questions to other populations. Namely, this paradigm can be used in the future to explore semantic processing of verbs and their thematic roles with individuals with aphasia. While these findings suggest that the semantic system re mains intact with aging, the paradigm could yield findings of the nature of the semantic system in persons with aphasia. These findings would be helpful in further supporting semantic treatment paradigms for aphasia, such as Verb Network Strengthening Tre atment (VNeST) (Edmonds et al., in press) and other related interventions.
39 APPENDIX A VERB RELATED AGENT PAIRS (WITH RELATEDNESS RA TINGS) AND VERB UNRELATED AGENT PAIR S Verb Related agent Average Relatedness ratings (1 7) SD Unrelated agent Accusing Pr osecutor 6.31 1.18 Audience Buying Customer 6.77 0.60 Bully Calculating Accountant 6.77 0.83 Actor Cleaning Janitor 6.69 1.11 Athlete Competing Athlete 6.69 1.11 Janitor Cooking Chef 6.85 0.55 Mechanic Defending Lawyer 6.46 1.33 Artist Delivering Ma ilman 7.00 0.00 Lawyer Driving Chauffer 6.77 0.83 Surgeon Fixing Mechanic 6.77 0.83 Champion Flying Pilot 6.62 1.12 Boss Hiring Boss 6.46 1.20 Pilot Interviewing Reporter 6.77 0.60 Butcher Investigating Detective 6.85 0.38 Quarterback Killing Assass in 6.92 0.28 Nun Lecturing Professor 6.77 0.60 Secretary Operating Surgeon 6.62 0.87 Detective Performing Actor 6.77 0.83 Customer Praying Nun 6.85 0.55 Reporter Serving Waitress 6.77 0.60 Professor Sewing Seamstress 6.69 1.11 Assassin Sketching Art ist 6.62 1.12 Prosecutor Slicing Butcher 6.77 0.83 Mailman Stealing Thief 6.62 1.12 Scholar Studying Scholar 6.69 0.85 Seamstress Teasing Bully 6.54 1.20 Chauffer Throwing Quarterback 6.77 0.83 Tourist Traveling Tourist 6.69 0.85 Waitress Typing Sec retary 6.77 0.83 Chef Watching Audience 6.62 1.12 Accountant Winning Champion 6.69 0.85 Thief 6.73 0.14
40 APPENDIX B VERB RELATED PATIENT PAIR S (WITH RELATEDNESS RATINGS) AND VERB UNRELATED PATIENT PA IRS Verb Related patient Average Relatedness rati ngs (1 7) SD Unrelated patient Arresting Criminal 6.38 1.50 Ice cream Baking Cookies 6.54 1.66 Envelope Brewing Coffee 6.54 1.13 Pizza Brushing Teeth 7.00 0.00 Money Celebrating Birthday 6.85 0.55 Dice Chewing Gum 6.85 0.38 Dishes Climbing Stairs 6. 69 1.11 Letter Drinking Juice 6.31 1.55 Lawn Grilling Chicken 6.85 0.38 Ribbon Inviting Guest 6.62 0.96 Bike Licking Popsicle 6.77 0.60 Sermon Mowing Lawn 6.69 1.11 Criminal Opening Envelope 6.85 0.55 Teeth Ordering Pizza 6.38 1.33 Stairs Pedaling Bike 6.62 1.12 Cookies Preaching Sermon 6.54 1.13 Gum Rolling Dice 6.23 1.79 Students Scooping Ice Cream 6.77 0.60 Juice Smoking Cigarette 6.62 1.39 Popsicle Spending Money 6.77 0.83 Song Singing Song 6.77 0.83 Coffee Teaching Students 6.77 0.83 Chi cken Tying Ribbon 6.85 0.38 Birthday Washing Dishes 6.85 0.55 Cigarette Wrapping Gift 6.62 1.39 Guest Writing Letter 6.69 1.11 Gift 6.67 0.19
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44 BIOGRAPHICAL SKETCH Sara Elisabeth Mizrahi was born in Jacksonville, FL. The oldest of four children, she grew up in Jacksonville in close proximity to her entire extended family. She graduated from Mandarin High School in 2002. She earned a Bachelor of Arts degree at Washington University in St. Louis in psychology and Jewish, Islamic, and near eastern studies in 2006. In the fall of 2006, Sara began her coursework in the Department of Communication Sciences and Disorders at the University of Florida. She graduated with a Master of Arts degree in speech language pathology in May 2009. Upon completio n of her M.A. program, Sara plans to pursue clinical work as a Speech Language Pathologist. Her interests include language processing and acquired neurological disorders.