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Age-Group Differences in Response Inhibition during an Emotional Go/No-go Task

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Age-Group Differences in Response Inhibition during an Emotional Go/No-go Task
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Buzzanca, Katherine E.
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English

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The ability to accurately read emotions across different age groups is a crucial skill throughout the lifespan in terms of socializing and creating and maintaining relationships. It has been found that as aging progresses, cognitive declines may hinder this ability to accurately read emotions. This study examined the differences between younger and older adults in their ability to accurately respond to emotional face stimuli during a go/no-go trial, while also investigating differences in reaction time as well as participant responses to own age faces. This study found that older compared to younger adults were slower in their reaction time during this task to identify these emotions. It was additionally found that there were no significant differences in accuracy between older and younger adults, nor were there significant differences in accuracy between younger and older adults when identifying own age faces. These findings suggest that age differences do in fact exist between older and younger adults in terms of reaction time when responding to emotional face stimuli and that these differences must be further looked at.       ( en )
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Awarded Bachelor of Science, magna cum laude, on May 8, 2018. Major: Psychology
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College or School: College of Liberal Arts and Sciences
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Advisor: Natalie Ebner. Advisor Department or School: Psychology

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University of Florida
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Copyright Katherine E. Buzzanca. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

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Running Head: AGE DIFFERENCES IN RESPONSE INHIBITION Age Group D ifferences in R esponse I nhibition during an E motional G o/ N o go T ask Katherine Buzzanca Supervised by: Dr. Natalie Ebner and Marilyn Horta Committee Members: Dr. Natalie Ebner (chair), Dr. M Jeff re y Farrar and Dr. Lisa Scott University of Florida

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AGE DIFFERENCES IN RESPONSE INHIBITION 2 ACKNOWLEDGMENTS I thank my committee chair, Natalie Ebner, as well as my co chairs, Jeffrey Farrar and Lisa Scott. I also thank Marilyn Horta, Tian Lin, and Ian Frazier for their guidance and motivation throughout this project.

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AGE DIFFERENCES IN RESPONSE INHIBITION 3 Abstract The ability to accurately read emotions across different age groups is a crucial skill throughout the lifespan in terms of socializing and creating and maintaining relationships. It has been found that as aging progresses, cognitive declines may hinder th is ability to accurately read emotions. This study examined the differences between younger and older adults in their ability to accurately respond to emotional face stimuli during a go/no go trial, while also investigating differences in reaction time as well as participant responses to own age faces. This study found that o lder compared to young er adults were slower in their reaction time during this task to identify these emotions. It was additionally found that there were no significant differences in a ccuracy between older and younger adults, nor were there significant differences in accuracy between younger and older adults when identifying own age faces. These findings suggest that age differences do in fact exist between older and younger adults in terms of reaction time when responding to emotional face stimuli and that these differences must be further looked at.

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AGE DIFFERENCES IN RESPONSE INHIBITION 4 Age Differences in Response Inhibition It is widely accepted that older adults experi ence a general cognitive decline that impacts performance in tasks that involve, but are not limited to, executive function (Cauffman et al., 2010; Olincy, Ross, Youngd, & Freedman, 1997; Sit & Fisk, 1999; Verhaeghen & Cerella, 2002) Executive function, a term used interchangeably with executive control refers to the capacity to pay attention to actions and thoughts while simultaneously utilizing knowledge from previous experiences to make appropriate, goal related decisions (Miller & Wallis, 2010) Response inhibition is a lower level cognitive process and function of executive control that involves the suppression of actions that are contextually inappropriate and interfere with goal driven behavior (Mostofsky & Simmonds, 2008) Response inhibition also describes the ability to inhibit pre determined actions in a dynamic environment. 1 From a developmental per spective, response inhibition is an ability that improves throughout childhood and young adulthood, however as aging progresses this ability diminishes (Williams, Ponesse, Schachar, Logan, & Tannock, 1999) Declines in executive function have been sh own to negatively impact daily life for older adults in regards to attention (e.g., shifting attention) working and long term memory, perception, speech and language, and decision making (Marshall et al., 2011) For example, o ne study looked at age related differences in the suppression of non target material and performance using a go/no go paradigm with visual, non emotionally salient stimuli 1 Similarly, selective attention refers to the ability to choose goal related targets and suppress actions directed towards irrelevant information (Samanez Larkin, Robertson, Mikels, Carstensen, & Gotlib, 2014; Vallesi et al., 2010) Response inhibition and selective attention can be exhibited simultaneously during decision making tasks. Ofte n, the terms selective attention, response inhibition, and selective inhibition are used interchangeably. For the purpose of this proposal, response inhibition will be referred to, rather than the term selective attention, and tested specifically.

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AGE DIFFERENCES IN RESPONSE INHIBITION 5 (Vallesi, Hasher, & Stuss, 2010) There were d ifferences in selective at tention between the young er and older adults in that advanced ag e wa s associated with the failure to suppress irrelevant information. A study using the Victoria Stroop Test, a version of the paradigm in which the examiner interrupts and corrects the partic ipant once an error is made, examined response inhibition within healthy older adults (Troyer, Leach, & Straus s, 2006) Ratio time scores (scores that demonstrate the relationship between the time taken to complete the task and interference) were generated from the Victoria Stroop Test and indicated that interference was correlated with a slower response rate a nd increased errors. These results were compared to previously conducted studies and the results consistently found time scores that demonstrated increased interference with age (Delis, Kaplan, & Kramer, 2001; Ivnik, Malec, Smith, Tangalos, & Petersen, 1996; Klein, Ponds, Houx, & Jolles, 1997; West, 1999; Whelihan & Lesher, 1985) However, overall, findings on age differences in response inhibition are mixed, with s everal studies also suggesting no significant age effects For example, one study tested individuals from a wide age range ( 6 to 81 years ) regarding age differences in re sponse inhibition using the stop signal procedure, a paradigm that tests the ability to stop a planned or continuing thought and action (Williams et al., 1999) Images of e motionally salient human faces are arguably significant to nearly all individuals (Bruce & Young, 1998) and this significance can further increase when age is a common factor, referred to as own age bias (Anastasi & Rhodes, 2006; B ckman, 1991 ; Bartlett & Fulton, 1991; Lamont, Stewart W illia ms, & Podd, 2005; Mason, 1986; Perfect & Harris, 2003; Wright & Stroud, 2002) An additional factor, known as the own age effect (Ebner & Johnson, 2009) states that individuals are generally more exposed to people of their own age, and are therefore more familiar with faces that belong to their own age group. Both of these own age effects can

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AGE DIFFERENCES IN RESPONSE INHIBITION 6 have a great impact on the amount of attention that a person directs towards an emotionally salient image of a human face. Being more familiar with faces in one s own age group, in addi tion to experiencing own age bias, can lead to a slower response time for participants when presented with faces in the same age group. Thus it has been found that there is an increase in interference from own age faces (Ebner & Johnson, 2010) i n that participants become more distracted when presented with a face that is similar to their own age. Age related differences in e xecutive function have been found both in healthy and pathological aging and may be due to physiological changes, such as reductions in brain volume (Bennett & Madden, 2014; MacPherson, Phillips, Della Sala, & Sala, 2002) An alternative explanation comes from the notion that aging is associated with changes in motivation, such as reflected in the prioritization of emotionally meaningful goals over information seeking goals, as proposed by the Socioemotional Selectivity T heory (SST) (L. L. Carstensen, 1995) These changes in motivation could be attributed to changes in motivational and affective circuits in the aging brain that alter decision making (Samanez Larkin & Knutson, 2015) Age Differences in Response Inhibition to Social and Affective Stimuli Non significant age effects found in previous studies may be due to the use of non affective stimuli (i.e., fixation crosses, letters). It is possible that older compared to young er adults are more responsive to emotionally sali ent or arousing stimuli due to the motivational and attentional shift with advance age as described by SST (L. L. Carstense n, 1992) Understanding age related differences in executive functioning in social and emotional contexts is relevant because of the implications that executive functioning has on effectively carrying out everyday tasks which are typically social in nat ure (e.g., social decision making, social problem solving)

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AGE DIFFERENCES IN RESPONSE INHIBITION 7 (MacPherson et al., 2002; M uscara, Catroppa, & Anderson, 2008; Thornton & Dumke, 2005) However, c urrently very little is known about how declines in executive function are characterized in healthy aging within social and emotional contexts It is possible that e xecutive function and perceptual processing is influenced by affect through shifts in visual processing and direct attention observed in aging (Pessoa, 2009) The dual competition framework, presented by Pessoa ( 2009 ) which relates to the influence emotion and motivation can have on executive control, relays that perception and executive control occur simultaneously and are in competition with one another. When introduced, affective stimuli can impact this relat ionship between executive control and perceptual competition, strengthening stimulus driven processing and hindering task performance. At the neural level, these connections take place between the dorsolateral prefrontal cortex and the anterior cingulate c ortex (Pessoa, 2009) Further, changes in executive function with age affect these connections, which may lead to greater visual attention towards emotional stimuli. While similar brain regions are im plicated in both executive function and affective processing (i.e., the amygdala, anterior cingulate cortex, and the dorsolateral prefrontal cortex) (Corbetta & Shulman, 2002; Kastner & Unge rleider, 2000) affective stimuli receive prioritized attention over non affective stimuli (Harris, Pashler, & Coburn, 2004) Assessment of Age Differences in Response Inhibition in Social and Affective Contexts Different tasks have been used to measure response inhibition (i.e the Stroop Task, Go / No go task) H owever, many of them have not been used in older adults, and even less apply to socioemotional context s The Stroop paradigm constitutes a typical non social, non affective cognitive task to measure response inhibition (Stroop, 1935) It measures response inhibition and respons e interference, that is the decline of performance when a desired response must be

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AGE DIFFERENCES IN RESPONSE INHIBITION 8 suppressed and instead the irrelevant response must be given (Richler, Cheung, Wong, & Gauthier, 2009; Stins, Polderman, Boomsma & De Geus, 2007) There are variations of this task that are more emotionally salient One such variation used auditory stimuli to present an emotionally salient word in a contrasting tone of voice (Wurm, Labouvie Vief, Aycock, Rebucal, & Koch, 2004) In this task, older adults had a slower response rate in comparison to young er adults to the critical emotion words. Another variation of the Stroop paradigm presents emotionally arousing faces with an overlying contrasting emotional word. There is only limited research using this paradigm in regards to healt hy aging, but existing evidence suggests impairments in goal related tasks in older adults (Berger & Davelaar, 2015) The G o/ N o go T ask was designed to assess response inhibition throug h the ra p id p resentation of stimuli. Similar to a two choice procedure, participants are required to respond to one choice (go stimulus) by pressing a response key, however they must suppress their response for another choice (no go stimulus) (Gomez, Ratcliff, & Perea, 2009) The stimuli are typically presented in a pseudorandom order and in quick succession to maintain participant engagement. There are multiple variations of stimuli, ranging from non affective (e.g., letters, objects) to emotionally salient (e.g., faces, emotionally arousing scenarios) Purpose of the Proposed Study Ther e is some evidence of i mpaired response inhibition in older compared to young er adults with non affective stimuli (Troyer et al., 2006; Williams et al., 1999) A ge differences in response inhibition related to socioemotional stimuli however, are currently understudied. Therefore, the present study will set out to investigate differences in response inhibition among young er and older adults using an emotional go/no go task. The following research question s and associated hypothes e s will be addressed:

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AGE DIFFERENCES IN RESPONSE INHIBITION 9 (1) Does adult age (young er vs. older) affect response inhibition during an emotional go/no go task? (i.e., main effect of age). I hypothesize that older compared to young er adults will be slower ( Hypothesis 1a ) and less accurate ( Hypothesis 1b ) in inhibiting res ponses to the emotional face stimuli (2) Does the age (youn ger vs. old er ) of the face stimuli influence performance during an emotional go/no go task? I hypothesize that older and younger adults will be slower ( Hypothesis 2a ) and less accurate in responding to their own age ( Hypothesis 2b ) compared to other age, faces regardless of emotion Methods The proposed project is part of a larger study, including functional magnetic resonance imaging (fMRI) conducted as a collaboration between t he Social Cognitive and Affective Development (Ebner) Lab at the University of Florida and the Adult Development and Decision (Lighthall) Lab at the University of Central Florida to examine consumer and affective judgements in young er and older adults. Data collection for young er adults has already been completed and data collection for older adults is currently underway. Participants The study includes 24 healthy young er adults (age 18 35 years) and 15 healthy older adults (age 65 90 years ; target n = 26 ; data collection is ongoing for this sample ) An original sample of 26 young er adults were consented into the study, but two young er participants were not included in the present project due to missing data. Participants were recruited via lab internal participant databases flyer advertising and word of mouth in the Gainesville community and Orlando area. Young er participants receive d either 5 course credits or $30 (in cash or electronic gift cards) for participating. Older participants receive d $50 (i n cash or electronic gift cards) to make up for the increased time commitment over two sessions (versus

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AGE DIFFERENCES IN RESPONSE INHIBITION 10 only one for young er participants ). Both age groups were comprise d of a pproximately equal numbers of women and men. P articipants must be right handed (for reason of comparability of brain anatomy) and generally healthy and meet MRI eligibility criteria Further, o lder participants must score 30 or higher on the Telephone Interview of Cognitive Status (Brandt, Spencer, & Folstein, 1988) indicating no cognitive impairment relating to dementia. Separate one way univariate analyses revealed no significant age group differences in mood as measured by the Positive and Negative Affect Schedule (PANAS) (Watson, Clark, & Tellegen, 1988b) or years of education between youn ger and older adults (See Table 1) While older adults did have a higher average for years of education, this is an expected finding due to the fact that some of the younger adult age group has not yet had the opportunity to complete their education Proc edure Prior to study enrollment, initial contact was made by phone call in which young er and older participants complete d a phone screening to determine eligibility. Young er and older p articipants will verbally consent to participating in the phone screening portion of the study. Eligible p articipants will then arrive at the McKnight Brain Institute at the University of Florida are consented, review the task instructions and p ractice trials, receive information regarding the MRI scanning procedure in the 3T Philips MRI scanner. Prior to the MRI scan, participants respond to a series of questionnaires relating to their demographics, health, mood, decision making processes, and MRI eligibility for about 30 minutes. The following questionnaires are inc luded: the lab internal Demographic and Health Information Form, the Behavioral Inhibition/Behavioral Activation Scale to measure levels of appetitive and avoidance motivation (Carver & White, 1994) the General Decision Making Style Invent ory (Scott &

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AGE DIFFERENCES IN RESPONSE INHIBITION 11 Bruce, 1995) the Melbourne Decision Making Q uestionnaire (Mann, Burnett, Radford, & Ford, 1997) the Empathy Quotient Questionnaire (Baron Cohen & Wheelwright, 2004) the Interpersonal Reactivity Inde x (Davis, 1980) and the MRI Eligibility Form provided by the imagi ng facility Responses to these questionnaires will not be included in the proposed thesis apart from the demographic and health information which will be used to describe the current sample. Participant s will then engage in a consumer judgment task (the main project task, which will not be reported in this senior thesis) and anatomical image acquisition for a total of 90 minutes. After the MRI scan, participants complete various tasks on a laptop, including a behavioral version of the emotional go/no go task as described in detail below (Somerville, Hare, & Casey, 2011) At the end of the session, participants complete a post event questionnaire about their experience in the scanner and are debriefed and compensated. The following modifications in the procedure of the experimental sessions were implemented for the data collection of older adults. Specifically, older participants complete d the study in two separate visits rather than one to ease partic ipant burden On Day 1 (30 50 min) older participants completed the questionnaires, MRI eligibility, and the Emotional Go/No go task. During this visit, participants also received instructions on scanning procedure and on Consumer Judgement Task Older participants came to either the Ebner lab at UF (if recruited in Gainesville) or the Lighthall lab at UCF (if recruited in Orlando) On Day 2 (90 120 min) older participants will come to the behavioral test room at the McKnight Brain Institute a nd complete the Positive and Negative Affect Schedule (Watson et al., 1988b) They will then review the task instructions and practice trials and receive scanning procedur e information. The experimenter will then prepare participants for scanning. The scan session for older adults is

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AGE DIFFERENCES IN RESPONSE INHIBITION 12 identical to that for young er adults. After scanning is complete, participants will complete a post event questionnaire about their experience in the scanner, be debriefed, and compensated Emotional Go/No Go Task Parameters The task was presented using Eprim e software (version 2.0) on a Dell laptop (Intel Core i7, 7 th generation model). Responses and reaction times were recorded by the software program. Face stimuli used for the Emotional Go/No Go task were from the FACES Lifespan Database (Ebner, Riediger, & Lindenberger, 2010) which comprise s of 2,052 young er and older men and women aged 19 to 80 wearing gray shirts upon a gray background Data were acquired in 96 behavioral trials representing each combination of facial emotion (happy, neutral) and response (go, no go). There were two conditions of the task in order to counterbalance the task instructions across participants : happy/neutral and neutral/happy Participants were randomly assigned to the task condition The happy /neutral condition instructed that participants press a key whenever a happy face appears (go trials, 36 trials) and not to press a key (no go, 12 trials) when a neutral face appeared. Du ring the neutral /happy condition of the study, participants were instructed to press a key when a neutral face was presented (go, 36 trials), and to not press a key when a happy face was presented (no go, 12 trials). Participants completed both conditions but were randomly assigned to which condition was presented first. There was a 30 second break after completion of one of the two experimental conditions. A total of 36 go neutral and 12 no go happy faces were presented in a pseudorandom order. The neutra l/happy condition of the task followed this same format, but the instructions were reversed totaling to 96 trials altogether

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AGE DIFFERENCES IN RESPONSE INHIBITION 13 In both conditions, stimuli contained an equal amount of female ( 24 ) and male faces ( 24 ) as well as an equal amount of older ( 24 ) and young er faces ( 24 ), for the two facial expressions happy ( 24 ) and neutral ( 24 ). Each face identity was only presented once throughout the task As shown in Figure 1, each face was presented for 5 seconds during which participants had to give their response Facial emotion was counterbalanced across participants by presenting in pseudo random ized order with no more than four same age face s no more than four same gender faces, and no more than seven same em otion faces presented in a row for both trials. The jittered fixation ranged from 2 .0 to 14.5 seconds in the happy/neutral condition and from 2.5 to 11.5 seconds in the neutral/happy condition. 2 A nalysis To test my study hypotheses both r eaction time and accuracy data was analyzed using SPSS Two separate mixed model univariate analyses of variance (ANOVA) were used to test the four hypothesis. The first mixed model ANOVA examined differences in reaction time, the dependent variable, with the age group of face stimuli as the within subject factor and the participant age group as the between subject factor ( Hypothesis 1a and 2a ). The second examined differences in accuracy, the dependent variable, with the age group of face stimuli as the wi thin subject factor and the participant age group as the between subject factor ( Hypothesis 1b and 2b ). In particular, hit (correct response), miss (incorrect lack of response), correct rejection (correct withholding of response), and false alarm (incorrec t response) rates were calculated for younger and older face stimuli respectively D prime signal detection analysis 2 Due to a programming oversight, the jittered fixation range varied from 2000ms to 14500ms for happy/neutral and 2500ms to 11500ms for neutral/happy, which resulted in a mean difference of about 83.3ms. This variation was counterbalanced during the collection of older adult data, in which half of the older adults completed the task with a jittered fixation of 2500ms to 11500ms for happy/neutral and 2000ms to 14500ms for neutral/happy.

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AGE DIFFERENCES IN RESPONSE INHIBITION 14 was used to calculate accuracy by computing hits to determine response bias. Results Hypothesis 1 a and 1b Preliminary assumption testing was used to check for normality and homogeneity of variance covariance matrices, noting no serious violations. A p < .05 level indicated s ignificant differences in mean reaction time between the two age groups ( H ypothesis 1a) ; F (1, 40) = 14.18, p = .00, p 2 = .27. These results show ed that younger adults ( M = 537.86; SD = 87.35) were significantly faster in reaction time than older adults ( M = 672.49; SD = 139.43). Additionally, statistically significant differences were not found for the effect of age on accuracy ( H ypothesis 1b); F (1,40) = .01, p = .94, p 2 = .00. The interaction between the age of the participants and the age of face stimuli was not significant; F (1,40) = 1.74, p = .195, p 2 = .04. Hypothesis 2a and 2b Preliminary assumption testing was used to check for normality and homogeneity of variance covariance matrices and no serious violations were noted. There were no differences in reaction time to own versus other age faces ( H ypothesis 2a) ; F (1,40) = 1.9 5, p = .17, p 2 = .05. Additionally, no significant difference w as found across age groups for accuracy ( H ypothesis 2b); F (1,40) = 1.33, p = .26, p 2 = .03. Lastly, the interaction between the age of the participants and the age of the face stimuli were not significant; F (1,40) = 1.33, p = .26, p 2 = .03. Discussion Older a dults were slower but not less accurate, than young adults in the emotional g o n o g o task

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AGE DIFFERENCES IN RESPONSE INHIBITION 15 Hypothesis 1a and 1b This study aimed to look at differences in reaction time between older and younger adults and in response to own age versus other age faces. Hypothesis 1a predicted that older adults would be slower in reaction time, and findings of this study support this hypothesis. While older adults were slower in their reaction time, it is a possibility that if other emotions were to be added to the task that there would be more variability in reaction times for correct go trials of both young and older adults. Hypothesis 1b predicted that older adults would also be less accurate than younger adults when responding to own versus other age faces, however findings did not support this hypothesis. The fact that older adults are more accurate is in line with what some preexisting research has found (Salthouse, 1979; Schuch, 2016) Additional research into these differences in accuracy between older adults suggest that there may be a tradeoff between accuracy and speed within the older adult population during two choice tasks (Ratcliff, Thapar, & McKoon, 2013) Further, older adults may choose being accurate over responding quickly to tasks when presented with the option (Starns & Ratcliff, 2010) Hypothesis 2a and 2b Hypothesis 2a predicted that younger and older adults would be slower in responding to their own age faces rather than other age faces, however findings did not support this hypothesis. Significant differences were not found in the average reaction time for both younger and older adults in response to own age and other age face stimuli. T hese findings may be due to the fact that the task was relatively easy and responding to either one s own age or a different age was not a challenge for participants. Hypothesis 2b aimed to answer whether or not the age of the emotional face stimuli used influenced accuracy during an emotional go/no go task. It was hypothesized that young er and older adults would be less accurate in their performance in the task when responding to own age,

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AGE DIFFERENCES IN RESPONSE INHIBITION 16 compared to other age faces. While younger and older adults did perform along the lines of what was hypothesized, differences in accuracy scores between the two age groups and in relation to their own face age were not statistically significant These findings do not support the hypot hesis that young er and older adults would be less accurate in their task performance when responding to own age faces. It has been found that age and emotion affect the amount of time an individual spends looking at an emotional face stimuli (Ebner, He, & Johnson, 2011) and this prolonged looking time can ultimately affect the amount of time that an individual takes to respond to a stimuli. One reason that a statistically si gnificant difference in the two age groups was not found could be because of the emphasis on accuracy that both groups aimed for during the task M eaning that a trade off between accuracy and reaction time may be present and that being accurate may be more of a goal for the two age groups than being quick in response time. Limitations The task only consisted of two emotions and was therefore not as challenging as some other go/no go tasks that consist of more emotional face stimuli. Supporting this, t here was a ceiling effect, in that most participants had a high rate of accuracy. Further, b ecause of the limit on emotional stimuli and the fact that there are many more emotions that are presented on the human face in everyday life, this study can only show a slight representation of differences between response inhibition and emotional processing in age. In addition to other emotions, the speed and accuracy trade off was not examined in the present thesis and this is an aspect that future research should a im to investigate. Because the study is still ongoing, all of the older adult data has not been collected. Larger sample sizes may have contributed to more significant findings.

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AGE DIFFERENCES IN RESPONSE INHIBITION 17 The use of a cross sectional design, rather than a longitudinal design, cre ates another limitation for the study. With a cross sectional design, it is uncertain if differences exist between cohort or between age and in order to test change, a longitudinal design is necessary (Ployhart & Vandenberg, 2010; Schaie & Willis, 2011) Because a longitudinal approach is very time and cost intensive, it is less frequently used and future research needs to adopt a longitudinal or a cross sequential design in order to differentiate between these cohort effects and discuss change. Future Directions While it was shown that older adults are slower in their overall reaction time when compared to younger adults, this study does not take into consideration whether or not these older adults could be suffering from initial stages of a disease, s d ementia. The higher amount of variability that was found within the reaction times of the older adults suggests that there is likely more variables to consider in the older adult population than there is in that of young er adults and it may be possible that these changes are attributed to an undetected early onset of a disease or more simply age related executive dysfunction (Georgiev, Dirnberger, Wilkinson, Limousin, & Jahanshahi, 2016) A future direction for this study would be to extend on current findings and examine the cognitive status of older adults. Alt hough the Telephone Interview of Cognitive Status was an eligibility criterion for the existing study, it would be beneficial to compare the scores of the measure across participants when looking at reaction time. It is currently known that patients with P D become increasingly slow in decision making (Cooper, Sagar, Tidswell, & Jordan, 1994) and s tudies that use d the go/no go paradigm have found that PD patients made more anticipatory errors than their healthy, age matched controls. Additionally, s tudies that have focused on AD in relation to the go/no go task have found that when compared to norma l older adult s AD patients have a significantly higher average reaction

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AGE DIFFERENCES IN RESPONSE INHIBITION 18 time as well as amount of errors made (Terasawa et al., 2014) While it is important to understand how neurodegenerative disease affect cognition and be havior in aging, healthy older adults also undergo age related cognitive changes that impact dail y life and social interactions (Harada, Natelson Love, & Triebel, 2013) Therefore, future directions of this study could aim to better understand the implications of pathol ogical aging on cognition as well as executive It can also be argued that the greater standard deviation of older adults in terms of reaction time and accuracy may be the product of habituation and fatigue. It is possible that h abituation, or the decline of psychological and emotional response to a repeated stimulus, could vary between younger and older adults during sessions due to the fact that there are differences in the level of emotional reactivity between younger and older adults. Studies have found that as people become older, they are better able to regulate their responses to emotional situations due to prolonged exposure and experience (Birditt, Fingerman, & Almeida, 2005; Calder et al., 2003; L. Carstensen et al., 2011) In addition to habituation, results of olde r adults may also vary due to an increase in fatigue that older adults experience (Allman & Rice, 2003; Avlund, 2 010; Eldadah, 2010) Although fatigue may play a role for the task performance of older adults, this study did aim to limit fatigue during sessions by splitting the session into two days for older adults, rather than one day for young er adults. Future analysis can help determine effects of habituation or fatigue trial by trial individual change in reaction and accuracy. Conclusion The findings of the present study provide evidence for age having an effect on response inhibition during an emotio nal go/no go task. Specifically, older adults were slower in reaction time to respond to emotional stimulus No significant differences in accuracy in response to own

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AGE DIFFERENCES IN RESPONSE INHIBITION 19 age rather than other age faces were noted, however this could be due to several factors, including a small sample of older adults and a potential ceiling effect due to the relatively unchallenging nature of the task Much of the research on response inhibition in older, compared to young er adults prior to this study had been conduc ted without the use of affective stimuli and this research presented some evidence of altered response s in older adults. It has been demonstrated that differences do exist between older and young er adults in terms of response inhibition to affective stimul i, suggesting that older adults do in fact suffer from cognitive declines that impact their reaction time However, it is still unclear how aspects such as trade offs between accuracy and reaction time, variations in cognitive status, habituation, or fatig ue could play a role. Future research needs to be focused on investigating these features and the effects that they have on response inhibition in aging in order to provide a more accurate depiction of how response inhibition develops across non pathologic al aging.

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AGE DIFFERENCES IN RESPONSE INHIBITION 20 References Allman, B. L., & Rice, C. L. (2003). Perceived exertion is elevated in old age during an isometric fatigue task. European Journal of Applied Physiology 89 (2), 191 197. https://doi.org/10.1007/s00421 002 0780 4 Anastasi, J. S., & Rhodes, M. G. (2006). Evidence for an own age bias in face recognition. North American Journal of Psychology, 8 (2), 237 252. https://doi.org/10.3758/BF03206441 Avlund, K. (2010). Fatigue in older adults: An early indicator of the aging process? Aging Clinical and Experimental Research 22 (2), 100 115. https://doi.org/10.1007/BF03324782 B ckman, L. (1991). Recognition memory across the adult life span: The role of prior knowledge. Memory & Cognitio n 19 (1), 63 71. https://doi.org/10.3758/B F03198496 Baron Cohen, S., & Wheelwright, S. (2004). The empathy quotient: an investigation of adults with Asperger syndrome or high functioning autism, and normal sex differences. Journal of Autism and Development al Disorders 34 (2), 163 175 Retrieved fr om http://www.ncbi.nlm.nih.gov/pubmed/15162935 Bartlett, J. C., & Fulton, A. (1991). Familiarity and recognition of faces in old age. Memory & Cognition 19 (3), 229 238 Bennett, I. J., & Madden, D. J. (2014). Disconnected aging: Cerebral white matter integrity and age related differences in cognition. Neuroscience 276 187 205. https://doi.org/10.1016/j.neuroscience.2013.11.026 Berger, N., & Davelaar, E. (2015). Effects of emotion and age on cognitive control in a Stroop Task. EAP Cognitive Science 370 3 75. Birditt, K. S., Fingerman, K. L., & Almeida, D. M. (2005). Age differences in exposure and reactions to interpersonal tensions: a daily diary study. Psychology and Ag ing 20 (2), 330

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AGE DIFFERENCES IN RESPONSE INHIBITION 24 related differences in stroop interference. Journal of Clinical and Experimental Neuropsychology 19 (1), 77 82. https: //doi.org/10.1080/01688639708403838 Lamont, A. C., Stewart Williams, S., & Podd, J. (2005). F ace recognition and aging: Effects of target age and memory load. Memory & Cognition 33 (6), 1017 1024. https://doi.org/10.3758/BF03193209 MacPherson, S. E., Phillips, L. H., Della Sala, S., & Sala, S. Della. (2002). Age, Executive Function, and Social Dec ision Making: A Dorsolateral Prefrontal Theory of Cognitive Aging. Psychology and Aging 17 (4), 598 609. https://doi.org/10.1037//0882 7974.17.4.598 Mann, L., Burnett, P., Radford, M., & Ford, S. (1997). The Melbourne decision making questionnaire: an instrument for measuring patterns for coping with decisional conflict. Journal of Behavioral Decision Making 10 (1), 1 19. https://doi.org/10.1002/(SICI) 1099 0771(1997 03)10:1<1::AID BDM242>3.0.CO;2 X Marshall, G. A., Rentz, D. M., Frey, M. T., Locascio, J. J., Johnson, K. A., & Sperling, R. A. (2011). Executive function and instrumental activities of daily living in mild cognitive impairment and Alzheimer s disease. Alzheimer s and Dementia 7 (3), 300 308. https://doi.org/10.1016/j.jalz.2010.04.005 Mason, S. (1986). Age and gender as factors in facial recognition and identification. Experimental Aging Research 12 (3), 151 154. https://doi.org/https://doi.or g/10.1080/0361 0738608259453 Miller, E. K., & Wallis, J. D. (2010). Executive function and higher order cognition: Definition and neural substrates. Encyclopedia of Neuroscience 4 99 104. https://doi.org/10.1016/B978 008045046 9.00418 6

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AGE DIFFERENCES IN RESPONSE INHIBITION 28 analyses. Neuroscience and Biobehavioral Reviews 26 849 857. https://do i.org/10.1016/S0149 7634(02)00071 4 Watson, D., Clark, L. A., & Tellegen, A. (1988a). Development and validation of brief measures of positive and negativ e affect: The PANAS scales. Journal of Personality and Social Psychology 54 (6), 1063 1070. Retrieved from http://psycnet.apa.org/psycinfo/1988 31508 001 Watson, D., Clark, L. A., & Tellegen, A. (1988b). Development and validation of brief measures of posi tive and negative affect: The PANAS scales. Journal of Personality and Social Psychology 54 (6), 1063 1070. Retrieved from http://psycnet.apa.org/psycinfo/1988 31508 001 West, R. (1999). Age differences in lapses of intention in the Stroop task. The Journa ls of Gerontology. Series B, Psychological Sciences and Social Sciences 54 (1), P34 43. https://doi.org/10.1093/geronb/54B.1.P34 Whelihan, W. M., & Lesher, E. L. (1985). Neuropsychological changes in frontal functions with aging. Developmental Neuropsychol ogy 1 371 380. Williams, B. R., Ponesse, J. S., Schachar, R. J., Logan, G. D., & Tannock, R. (1999). Development of inhibitory control across the life span. Developmental Psychology 35 (1), 205 213. https://doi.org/10.1037/0012 1649.35.1.205 Wright, D. B., & Stroud, J. N. (2002). Age differences in lineup identification accuracy: People are better with their own age. Law and Human Behavior 26 (6), 641 654. https://doi.org/10.1023/A:1020981501383 Wurm, L. H., Labouvie Vief, G., Aycock, J., Rebucal, K. A., & Koch, H. E. (2004). Performance in auditory and visual Emotional Stroop Tasks: A comparison of older and

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AGE DIFFERENCES IN RESPONSE INHIBITION 29 younger adults. Psychology and Aging 19 (3), 523 535. https://doi.org/10.1037/0882 7974.1 9 3.523

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AGE DIFFERENCES IN RESPONSE INHIBITION 30 Figure 1 This figure is a snapshot of the first half of the task to illustrate how responses were made for the different conditions It does not depict a 30 sec break and that the instructions switch after the first 4 8 trials and goes on for another 48.

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AGE DIFFERENCES IN RESPONSE INHIBITION 31 Table 1. Means and standard deviations for age group differences in education level for 2 6 younger participants and 1 6 older participants. Measures Young er Participants M (SD) Older Participants M (SD) Age group Differences Education Level (total years) 15. 00 (2. 56 ) 18.75 (3. 99 ) F(1, 42 ) = 13.83 p = 0. 00 2 p = 0. 26 Notes: Education level measured by total years of formal education (total years of education unavailable for one older participant).

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AGE DIFFERENCES IN RESPONSE INHIBITION 32 Table 2. Means and standard deviations for age group differences in mood for 25 younger and 12 older participants. Measures Younger Participants M (SD) Older Participants M (SD) Age group Differences PANAS; Positive Affec t 2.86 (0. 76 ) 3. 00 (0. 83 ) F(1, 35 ) = .30 p = 0. 592 PANAS; Negative Affect 1. 72 (0. 71 ) 1. 08 (0. 12 ) F(1, 35 ) = 30.71 p = 0. 00 Notes: Mood at the present moment was measured by the Positive Affect Negative Affect Scale (PANAS; Watson, Clark, & Tellegen, 1988) M = Mean, SD = Standard Deviation

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AGE DIFFERENCES IN RESPONSE INHIBITION 33 Figure 2 This graph shows reaction time s for younger and older adults in responding to own age versus other age faces. The E rror bars represent the standard error for the data set.

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AGE DIFFERENCES IN RESPONSE INHIBITION 34 Figure 3 This graph shows the levels of accuracy for younger and older adults in responding to own age versus other age faces The Error bars represent the standard error for the data set.