• Learning and recognizing faces across variability in appearance: An examination of children and older adults

      Matthews, Claire M.; Department of Psychology
      Recognizing facial identity requires two skills: telling a person apart from similar looking people and recognizing them across changes in their appearance. Until recently, the vast majority of studies relied on tightly controlled images to examine face learning and recognition. Research using ambient images (i.e., images that capture within-person variability in appearance) is necessary to assess the true challenge of face learning and recognition in daily life. Only a few studies have examined face learning and recognition using ambient images in children, and, to the best of my knowledge, no studies have examined them in older adults. My dissertation was designed to address these gaps in the literature. In Study 1, children aged 6 to 11 were tested to examine two mechanisms that underlie face learning in young adults: Ensemble coding and the ability to benefit from exposure to variability in appearance in a perceptual matching task. My results revealed that both mechanisms are adultlike by the age of 6. First, children extracted the average of a set of images of an identity, regardless of whether those images were presented simultaneously or sequentially. Second, although their overall accuracy was lower than that of young adults, children showed comparable benefit from viewing multiple images of a to-be-learned identity in a perceptual face learning task. In Study 2, I examined whether younger children (4- and 5-year-olds) benefit from exposure to multiple images when learning a new face in a perceptual task. Although viewing multiple images made young children more sensitive to identity, it also led them to adopt a less conservative response bias, driven both by an increase in hits and an increase in false alarms. This increase in false alarms was not found for older children and adults in Study 1, suggesting that the ability to benefit from exposure to variability in appearance during face learning is not fully refined before the age of 6. In Study 3, I provided the first examination of face learning and recognition in older adults using a battery of tasks. On three of the five tasks, older adults showed comparable learning and recognition to young adults: 1) Older adults recognized a familiar face without error; 2) they showed ensemble coding of facial identity, regardless of whether the images were presented simultaneously or sequentially and 3) despite making more errors than young adults overall, they showed comparable benefit from viewing multiple images of a newly encountered face in the perceptual learning task. In the remaining two tasks, older adults showed a different pattern than young adults: 1) Older adults made fewer hits and more false alarms than young adults when matching images of wholly unfamiliar faces; and 2) after being exposed to low variability in appearance in a face memory task, older adults became more conservative than did younger adults, despite showing comparable benefits in sensitivity. My results reveal that the same abilities that show prolonged development during childhood are those undergo changes in aging. Collectively, my dissertation provides novel insights about learning and recognizing facial identity during childhood and aging and has important implications for understanding models of face processing.
    • The light and dark sides of perfectionism : implications for health and well-being

      Sirianni Molnar, Danielle; Department of Psychology (Brock University, 2011-10-14)
      The present work presents two studies that examined the association of perfectionism, operationally defined by Hewi t t and Fl e t t ' s (1991) multidimensional mode l of perfectionism, with health and subjective well-being (SWB). The underlying question of this research was whether perfectionism could be beneficial as well as detrimental to health and well-being, as this is one of the mos t highly debated questions in the current literature. In samples of relatively healthy university students (n = 538) and community adults suffering from various chronic illnesses (n = 772), results from Study One indicated that socially prescribed perfectionism (SPP) is directly associated wi th poor e r he a l th and well-being. Results further showed f rom a personcentered perspective that there is a l a rge group of individuals wi th high levels of SPP and that i t is indeed these individuals who reported the poorest health and lowe s t levels of well-being. Other-oriented perfectionism was found to be unrelated to health and SWB. Findings revealed that when perfectionism is self-imposed (i.e., self-oriented perfectionism; SOP), i t is neither healthy nor unhealthy in an absolute sense. From the variable-centered perspective, this conclusion was supported by the f a c t tha t SOP was associated wi th both positive (e.g., be t t e r mental health and highe r levels of SWB in the student sample), and nega t ive correlates (e.g., higher levels of negative affect, stress, and neuroticism in both samples). Evidence f rom the chronically-ill sample further substantiated this conclusion by showing that there may be an optimal level of SOP, because mode r a t e levels of SOP we r e found to be associated with be t t e r health and highe r levels of SWB, whereas levels tha t we r e too low or too high we r e found to be associated with poor e r health and lowe r levels of SWB. Findings f rom the person-centered approach we r e particularly informative, in that they not only demonstrated tha t unique profiles of
    • A Longitudinal Examination of Bidirectional Associations between Subjective Sleep Characteristics and Psychosocial Functioning among University Students

      Tavernier, Royette; Department of Psychology (Brock University, 2014-08-27)
      A number of studies have found a significant link between sleep and psychosocial functioning among university students. A critical examination of this literature, however, indicates that one important gap within the literature is the need for longitudinal studies that specifically test for bidirectional associations between these two constructs. The main purpose of my dissertation was to address this gap by conducting three studies that examined bidirectional associations between sleep and psychosocial functioning among a sample of university students. Participants were 942 (71.5% female) undergraduate students enrolled at a Canadian university, who completed survey assessments annually for three consecutive years, beginning in their first year of university. In the first study, I assessed bidirectional associations between two sleep characteristics (sleep quality and sleep duration) and three psychosocial functioning variables (academics, friendship quality, and intrapersonal adjustment). Results based on cross-lagged models indicated a significant bidirectional association between sleep quality and intrapersonal adjustment, such that more sleep problems predicted more negative intrapersonal adjustment over time, and vice versa. Unidirectional associations indicated that both higher academic achievement and more positive friendship quality were significant predictors of less sleep problems over time. In the second study, in which I examined bidirectional associations between sleep and media use, results provided support only for unidirectional associations; such that more sleep problems predicted increases in both time spent watching television and time spent engaged in online social networking. In the third study of my dissertation, in which I examined social ties at university and sleep quality, results indicated a significant bidirectional association, such that more positive social ties predicted less sleep problems over time, and vice versa. Importantly, emotion regulation was a significant mediator of this association. Findings across the three studies, highlight the importance of determining the direction of effects between different sleep characteristics and various aspects of university students’ psychosocial functioning, as such findings have important implications for both methodology and practice. A better understanding of the nature of the associations between sleep and psychosocial functioning will equip students, parents and university administrators with the tools necessary to facilitate successful adjustment across the university years.
    • A Longitudinal Examination of Indirect Effects involving Parenting, Temperament, and Antisocial Behavior in Adolescence

      Stoner, Amanda Jane; Department of Psychology
      The current dissertation examined whether authoritative parenting was indirectly related to adolescent antisocial behavior over time through adolescent temperament, and whether adolescent temperament was indirectly related to authoritative parenting over time through antisocial behavior. My original contribution to knowledge through this dissertation was to demonstrate the longitudinal, direct and indirect relations between a broad view of parenting, several aspects of temperament, and antisocial behavior during early adolescence. A community sample of 10- to 15-year-old male and female adolescents and their mothers responded to questionnaires at two times spanning 18 months. The dissertation is comprised of three studies, each focusing on a different aspect of temperament: effortful control in Study 1, affiliation in Study 2, and frustration in Study 3. In each study, two different models were tested. In the first model, path analyses were used to simultaneously estimate the direct and indirect effects between each of the Time 1 parenting dimensions (psychological autonomy granting, acceptance-involvement, knowledge, tracking, and limit setting) and Time 2 antisocial behavior through Time 2 adolescent temperament. In the second model, path analyses were used to simultaneously estimate the direct and indirect effects of Time 1 temperament on Time 2 parenting through Time 2 antisocial behavior. The analyses in the current studies used a statistically conservative approach in that the initial levels of both the mediators and outcome variables were controlled for in the path models. Results showed that even with high stability of temperament and antisocial behavior, parenting still related to changes over time in antisocial behavior directly and indirectly through adolescent temperament. Also, even with high stability of antisocial behavior and parenting, temperament still related to changes over time in parenting directly and indirectly through antisocial behavior. Overall, the current dissertation builds on the case for a temperament-based foundation of antisocial behavior, and shows that the link between parenting and antisocial behavior is sometimes indirect through adolescent temperament which itself uniquely accounts for changes in parenting, directly and indirectly through antisocial behavior. Applied implications and suggestions for future research are discussed.
    • The Mental Representation of Visual Information

      Robitaille, Joel; Department of Psychology
      Despite working in relative independence, the working memory and imagery literatures investigate the mental representation of visual information. Recent reports investigating the neural structure and their associated functional activity responsible for the creation and maintenance of these cognitive representations suggest a significant overlap between these fields of study. Because each field has adopted methodologies that does not allow for a direct comparison of the mental representation described by their respective literatures, it is difficult to determine whether imagery and working memory representations are related. Hence, the current thesis further investigates the properties of the visual representation of visual information to bridge between the imagery and working memory fields. In a first study, I compare the psychophysical properties of simple stimuli commonly used in working memory reports with more complex objects adopted by the imagery field. In the course of three experiments, I demonstrate that the cost of stimulus complexity predominantly affects the quality of the mental representation while still providing evidence of a shared cognitive mechanism driving the formation and maintenance of these representations. In a second study, I evaluate the impact of mental rotation on these mental representations as well as whether the adoption of different paradigms, along with different performance metrics, assess the same cognitive construct. Here again, I show strong evidence in support of a common cognitive mechanism driving the performance across mental manipulation and through assessment methods. Finally, the last study attempted to track the manipulation of these visual representations by applying an encoding model to raw EEG activity. While I show evidence of the orientation-relevant activity during perception, the encoding model does not detect reliable enough activity to allow for tracking the orientation of the stimulus during retention and mental rotation. Together, this thesis provides evidence of a shared cognitive mechanism that drives visual working memory and imagery representation, but tracking these mental representations using EEG activity during manipulation remains unclear.
    • Nonsuicidal Self-Injury and Suicidal Risk: An Examination among Young Adults

      Chloe, Hamza; Department of Psychology
      Nonsuicidal self-injury (NSSI), which refers to the direct and deliberate destruction of bodily tissue in the absence of suicidal intent, is a serious and widespread mental health concern. Although NSSI has been differentiated from suicidal behavior on the basis of non-lethal intent, research has shown that these two behaviors commonly co-occur. Despite increased research on the link between NSSI and suicidal behavior, however, little attention has been given as to why these two behaviors are associated. My doctoral dissertation specifically addressed this gap in the literature by examining the link between NSSI and several measures of suicidal risk (e.g., suicidal ideation, suicidal attempts, pain tolerance) among a large sample of young adults. The primary goal of my doctoral research was to identify individuals who engaged in NSSI at risk for suicidal ideation and attempts, in an effort to elucidate the processes through which psychosocial risk, NSSI, and suicidal risk may be associated. Participants were drawn from a larger sample of 1153 undergraduate students (70.3% female) at a mid-sized Canadian University. In study one, I examined whether increases in psychosocial risk and suicidal ideation were associated with changes in NSSI engagement over a one year period. Analyses revealed that beginners, relapsed injurers, and persistent injurers were differentiated from recovered injurers and desisters by increases in psychsocial risk and suicidal ideation over time. In study two, I examined whether several NSSI characteristics (e.g., frequency, number of methods) were associated with suicidal risk using latent class analysis. Three subgroups of individuals were identified: 1) an infrequent NSSI/not high risk for suicidal behavior group, 2) a frequent NSSI/not high risk for suicidal behavior group, and 3) a frequent NSSI/high risk for suicidal behavior group. Follow-up analyses indicated that individuals in the frequent NSSI/high risk for suicidal behavior group met the clinical cutoff score for high suicidal risk and reported significantly greater levels of suicidal ideation, attempts, and risk for future suicidal behavior as compared to the other two classes. Class 3 was also differentiated by higher levels of psychosocial risk (e.g., depressive symptoms, social anxiety) relative to the other two classes, as well as a comparison group of non-injuring young adults. Finally, in study three, I examined whether NSSI was associated with pain tolerance in a lab-based task, as tolerance to pain has been shown to be a strong predictor of suicidal risk. Individuals who engaged in NSSI to regulate the need to self-punish, tolerated pain longer than individuals who engaged in NSSI but not to self-punish and a non-injuring comparison group. My findings offer new insight into the associations among psychosocial risk, NSSI, and suicidal risk, and can serve to inform intervention efforts aimed at individuals at high risk for suicidal behavior. More specifically, my findings provide clinicians with several NSSI-specific risk factors (e.g., frequent self-injury, self-injuring alone, self-injuring to self-punish) that may serve as important markers of suicidal risk among individuals engaging in NSSI.
    • Novices' learning from the Internet : an exploration of navigation behaviours, learner-related factors, and mental effort

      Desjarlais, Malinda; Department of Psychology (Brock University, 2011-03-08)
      The current study was an exploration of why some novices are more successful than their peers when learning from the Internet by examining the relations among time spent with relevant information and changes in invested mental effort during Internet navigations as well as achievement. Navigation behaviours and learner characteristics were investigated as predictors of time spent with relevant information and changes in mental effort. Undergraduates (N = 85, Mage = 20 years, 5 months) searched the Internet for information corresponding to a low knowledge topic for 20 min while their eye gaze and pupil size were recorded. Pupil diameter was used as an objective, continuous measure of mental effort. Participants also completed questionnaires or computer tasks pertaining to s e l f-regulated learning characteristics (general intrinsic goal orientation and effort regulation) and cognitive factors (working memory control, distractibility and cognitive style). All analyses controlled for general mental ability, reading comprehension, topic and Internet knowledge, and overall motivation. A greater proportion of time spent with relevant information predicted higher scores on an achievement test. Interestingly, time spent with relevant information partially mediated the positive relation between the frequency of increases in invested mental effort and achievement. Surprisingly, intrinsic goal orientation was negatively related to time spent with relevant information and effort regulation was negatively related to the frequency of increases in invested mental effort. These findings have implications for supports when novices guide their own learning, especially when using the Internet.
    • Patterns of Endocrine, Behavioural, and Neural Function Underlying Social Deficits after Social Instability Stress in Adolescent Rats

      Hodges, Travis; Department of Psychology
      Adolescence is a time of social learning as well as a period of heightened vulnerability to stressors and enhanced plasticity, compared with adulthood. Previous research found that repeated social instability stress (SS; daily isolation and return to an unfamiliar peer from postnatal day (PND) 30 - 45) administered in adolescent rats alters social function when tested in adulthood. The main goal of my thesis research was to characterize how SS in adolescent rats affects the development of social brain regions and social behaviour when tested soon after the procedure. In chapter 2, I found that SS potentiated corticosterone release in rats repeatedly paired with an unfamiliar cage-mate after isolation compared with rats that were paired with an unfamiliar cage-mate for the first time after isolation on PND 45. In chapter 3, I found that in social interaction tests (i.e., not in home cage), SS rats had lower social interactions despite having higher social approach with unfamiliar peers relative to control (CTL) rats. Social stimuli carried the same reward value for SS and CTL rats based on tests of conditioned place preference, and SS in adolescence impaired social recognition. Further, SS increased oxytocin receptor density in the nucleus accumbens and dorsal lateral septum in rats compared with CTL rats. In chapter 4, I found that the correlations between time spent in social interaction with an unfamiliar peer and Fos immunoreactivity (a marker of neural activity) in the arcuate nucleus, dorsal lateral septum, and posterior medial amygdala were in the opposite direction in SS rats to those in CTL rats. In chapter 5, I found differences in the expression of proteins relevant for synaptic plasticity and in dendritic arborisation in the lateral septum and medial amygdala. My findings of behavioural and neural differences between SS and CTL rats highlight the heightened vulnerability of the brain to the quality of social experiences during the adolescent period that may lead to long-lasting deficits in social function in adulthood.
    • Physical Correlates of Sexual Orientation: The Association of Height, Birth Weight, and Facial Structure with Sexual Orientation.

      Skorska, Malvina N.; Department of Psychology
      Researchers have examined whether certain physical characteristics are associated with sexual orientation to gain insight into the mechanisms that may be implicated in its development. Three relatively new and/or understudied physical correlates (height, birth weight, facial structure) were investigated to determine whether they are reliably associated with sexual orientation and to gain insight into the specific mechanism(s) that may be driving the association between these physical correlates and sexual orientation. In Study 1, gay men were found to be shorter, on average, than heterosexual men in a nationally representative US sample. There was no significant height difference between lesbian and heterosexual women. No evidence was found that stress and nutrition at puberty mediated the association between sexual orientation and height in men. Thus, other mechanisms (e.g., prenatal hormones, genetics) likely explain the sexual orientation-height link. In Study 2, firstborn gay male only-children had, on average, a significantly lower mean birth weight than firstborn children in four other sibship groups. There was also evidence of increased fetal loss among mothers of gay male only-children. Birth weight and fetal loss have been shown to be indicators of a mother’s immune system responding to a pregnancy. Thus, Study 2 provides support for the idea that a maternal immune response (and one that appears to be distinct from the maternal immune response hypothesized to explain the traditional fraternal birth order effect) is implicated in sexual orientation development. In Study 3, lesbian and heterosexual women differed in 17 facial features (out of 63) at the univariate level, and four were unique multivariate predictors. Gay and heterosexual men differed in 11 facial features at the univariate level, and three were unique multivariate predictors. Some of the facial features related to sexual orientation implicated a sexual differentiation related mechanism (e.g., prenatal hormones), whereas others implicated a non-sexual differentiation mechanism (e.g., developmental instability) to explain the sexual orientation-facial structure association. In addition to extending the empirical literature on the physical correlates associated with sexual orientation, the studies included in this dissertation extend our understanding of the various mechanisms likely implicated in the development of sexual orientation.
    • Players and Avatars: The Connections between Player Personality, Avatar Personality, and Behavior in Video Games

      Worth, Narnia; Department of Psychology
      The increasing variety and complexity of video games allows players to choose how to behave and represent themselves within these virtual environments. The focus of this dissertation was to examine the connections between the personality traits (specifically, HEXACO traits and psychopathic traits) of video game players and player-created and controlled game-characters (i.e., avatars), and the link between traits and behavior in video games. In Study 1 (n = 198), the connections between player personality traits and behavior in a Massively Multiplayer Online Roleplaying Game (World of Warcraft) were examined. Six behavior components were found (i.e., Player-versus-Player, Social Player-versus-Environment, Working, Helping, Immersion, and Core Content), and each was related to relevant personality traits. For example, Player-versus-Player behaviors were negatively related to Honesty-Humility and positively related to psychopathic traits, and Immersion behaviors (i.e., exploring, role-playing) were positively related to Openness to Experience. In Study 2 (n = 219), the connections between player personality traits and in-game behavior in video games were examined in university students. Four behavior components were found (i.e., Aggressing, Winning, Creating, and Helping), and each was related to at least one personality trait. For example, Aggressing was negatively related to Honesty-Humility and positively related to psychopathic traits. In Study 3 (n = 90), the connections between player personality traits and avatar personality traits were examined in World of Warcraft. Positive player-avatar correlations were observed for all personality traits except Extraversion. Significant mean differences between players and avatars were observed for all traits except Conscientiousness; avatars had higher mean scores on Extraversion and psychopathic traits, but lower mean scores on the remaining traits. In Study 4, the connections between player personality traits, avatar traits, and observed behaviors in a life-simulation video game (The Sims 3) were examined in university students (n = 93). Participants created two avatars and used these avatars to play The Sims 3. Results showed that the selection of certain avatar traits was related to relevant player personality traits (e.g., participants who chose the Friendly avatar trait were higher in Honesty-Humility, Emotionality, and Agreeableness, and lower in psychopathic traits). Selection of certain character-interaction behaviors was related to relevant player personality traits (e.g., participants with higher levels of psychopathic traits used more Mean and fewer Friendly interactions). Together, the results of the four studies suggest that individuals generally behave and represent themselves in video games in ways that are consistent with their real-world tendencies.
    • Posttraumatic stress disorder symptoms might be destroying your intimacy : a test of mediational models in a community sample of couples

      Perrier, Colin; Department of Psychology (Brock University, 2011-03-08)
      The present research focused on the pathways through which the symptoms of posttraumatic stress disorder (PTSD) may negatively impact intimacy. Previous research has confirmed a link between self-reported PTSD symptoms and intimacy; however, a thorough examination of mediating paths, partner effects, and secondary traumatization has not yet been realized. With a sample of 297 heterosexual couples, intraindividual and dyadic models were developed to explain the relationships between PTSD symptoms and intimacy in the context of interdependence theory, attachment theory, and models of selfpreservation (e.g., fight-or-flight). The current study replicated the findings of others and has supported a process in which affective (alexithymia, negative affect, positive affect) and communication (demand-withdraw behaviour, self-concealment, and constructive communication) pathways mediate the intraindividual and dyadic relationships between PTSD symptoms and intimacy. Moreover, it also found that the PTSD symptoms of each partner were significantly related; however, this was only the case for those dyads in which the partners had disclosed most everything about their traumatic experiences. As such, secondary traumatization was supported. Finally, although the overall pattern of results suggest a total negative effect of PTSD symptoms on intimacy, a sex difference was evident such that the direct effect of the woman's PTSD symptoms were positively associated with both her and her partner's intimacy. I t is possible that the Tend-andBefriend model of threat response, wherein women are said to foster social bonds in the face of distress, may account for this sex difference. Overall, however, it is clear that PTSD symptoms were negatively associated with relationship quality and attention to this impact in the development of diagnostic criteria and treatment protocols is necessary.
    • Psychopathic Traits and Impulsivity Subtypes: An Examination of Two Complex, Multifaceted Constructs

      Hosker-Field, Ashley; Department of Psychology
      Research has demonstrated inconsistent results regarding the relationship between impulsivity and the interpersonal and affective facets of psychopathy. Therefore, the purpose of this work was to clarify and reconcile the variable empirical findings. Generally speaking, the relationship between psychopathic traits and impulsivity was expected to differ based on the psychopathy factor and type of impulsivity under investigation. Studies 1 and 2 examined psychopathy and impulsivity in on-line and student samples, utilizing the Self-Report Psychopathy Scale and several self-report measures of impulsivity. Study 2 included laboratory-assessed behavioural impulsivity measures. Results indicated that across studies erratic lifestyle was uniquely, positively associated with all self-reported impulsivity measures, but surprisingly unrelated to laboratory-assessed behavioural impulsivity. Interpersonal manipulation was uniquely, negatively associated with lack of premeditation and non-planning, and callous affect was uniquely, negatively associated with urgency across studies. Studies 3 and 4 examined the psychopathy-impulsivity relationship in youth and on-line samples. Psychopathy was examined using the Antisocial Process Screening Device (youth) and the Self-Report Psychopathy Scale (adults). Impulsivity was approximated via preselected facets of the HEXACO-PI-R and the UPPS Impulsive behavior scale (Study 4 only). Results indicated that the impulsivity (youth) and erratic lifestyle (adults) subscales were uniquely associated with heightened impulsivity. Callous-unemotional traits in youth were also associated with higher levels of impulsivity. In adults, interpersonal manipulation and callous affect were largely unrelated to impulsivity at the multivariate level (with few exceptions). Findings demonstrated that the behavioural characteristics of psychopathy contributed to a pervasive tendency towards a variety of impulsive behaviours. This relationship was consistent across the youth, adult, on-line, and student samples. Among adults, the emotional and interpersonal psychopathy traits may be unrelated to impulsivity. Interpersonal manipulation traits may result in a slightly greater tendency to demonstrate premeditated, planned behaviour, whereas callous affect may reflect slightly lower urgency. However, callous-unemotional traits in youth do appear to be related to heightened impulsivity. Findings provide a better understanding of the psychopathy-impulsivity relationship. This is the first set of studies to utilize the HEXACO model to approximate pre-established impulsivity domains. Findings also address the issue of suppression when examining multifaceted constructs, particularly psychopathic traits.
    • Recognizing Own- and Other-race Faces: Cognitive Mechanisms Underlying the Other-Race Effect

      Zhou, Xiaomei; Department of Psychology
      Other-race faces are discriminated and recognized less accurately than own-race faces. The other-race effect (ORE) emerges during infancy and is robust across different participant populations and a variety of methodologies (Meissner & Brigham, 2001). Decades of research has been successful in characterizing the roots of the ORE, however certain aspects regarding the nature of own- and other-race face representations remain unspecified. The present dissertation attempts to find the commonalities and differences in the processing of own- vs. other-race faces so as to develop an integrative understanding of the ORE in face recognition. In Study 1, I demonstrated that the ORE is attributable to an impaired ability to recognize other-race faces despite variability in appearance. In Study 2, I further examined whether this ability is influenced by familiarity. The ORE disappears for familiar faces, suggesting a fundamental difference in the familiar and unfamiliar other-race face recognition. Study 3 was designed to directly test whether the ORE is attributable to a less refined representation of other-race faces in face space. Adults are more sensitive to deviations from normality in own- than other-race faces, and between-rater variability in attractiveness rating of individual faces is higher for other- than own-race faces. In Study 4, I investigated whether the ORE is driven by the different use of shape and texture cues. Despite an overall ORE, the transition from idiosyncratic shape to texture cues was comparable for own- and other-race faces, suggesting that the different utilization of shape and texture cues does not contribute to the ORE. In Study 5, applying a novel continuous-response paradigm, I investigated how the representations of own- and other-race face are stored in visual working memory (VWM). Following ample encoding time, the ORE is attributable to differences in the probability of a face being maintained in VWM. Reducing encoding time caused a loss of precision of VWM for other- but not own-race faces. Collectively, the results of this dissertation help elucidate the nature of representations of own- and other-race faces and clarify the role of perceptual experience in shaping our ability to recognize own- and other-race faces.
    • Relation of temperament and authoritative parenting on subtypes of adolescent behaviour

      Reker, Dana L.; Department of Psychology (Brock University, 2011-03-08)
      Over the years, researchers have investigated direct, conditional, and meditational pathways of adolescent aggression in relation to both temperament and parenting behaviours. However, no study to date has considered these relations with respect to a measure of aggression differentiated by form (e.g., overt, relational) and function (e.g., proactive, reactive). The present study examined the differential association of adolescent temperament and authoritative parenting on four subtypes of aggression. Participants included mothers, fathers, and one adolescent (between the ages of 10-19) from 663 families, recruited through random digit dialing. Parents reported on their child's temperament and occurrence of aggressive behaviours in addition to the perception of their own authoritative parenting. Adolescents reported on their own temperament and aggressive behaviours as well as on both their mother and father's authoritative parenting. Multiple regression analyses confirmed predictions that some aspects of temperament and authoritative parenting provide motivation towards the engagement of different aggressive behaviours. For example, higher negative affect was related to reactive types of aggression, whereas a strong desire for novel or risky behaviours related to proactive aggression. However, differences in effortful control altered the trajectory for both relationships. Higher levels of self-regulation reduced the impact of negative affect on reactive-overt aggression. Greater self-regulation also reduced the impact of surgency on proactive-overt aggression when age was a factor. Structural equation modeling was then used to assess the process through which adolescents become more or less susceptible to impulsive behaviours. Although the issue ofbi-directionality cannot be ruled out, temperament characteristics were the proximal correlate for aggression subtypes as opposed to authoritative parenting dimensions. Effortful control was found to partially mediate the relation between parental acceptancelinvolvement and reactive-relational and reactive-overt aggression, suggesting that higher levels of warmth and support as perceived by the child related to increased levels of self-regulation and emotional control, which in tum lead to less reactive-relational and less reactive-overt types of aggression in adolescents. On the other hand, negative affect partially mediated the relation between parental psychological autonomy granting and these two subtypes of aggression, supporting predictions that higher levels of autonomy granting (perceived independence) related to lower levels of frustration, which in tum lead to less reactive-relational and reactive-overt aggression in adolescents. Both findings provide less evidence for the evocative person-environment correlation and more support for temperament being an open system shaped by experience and authoritative parenting dimensions. As one of the first known studies examining the differential association of authoritative parenting and temperament on aggression subtypes, this study demonstrates the role parents can play in shaping and altering their children's temperament and the effects it can have on aggressive behaviour.
    • The Role of Experience in the Organization and Refinement of Face Space

      Short, Lindsey; Department of Psychology (Brock University, 2014-09-12)
      Adults code faces in reference to category-specific norms that represent the different face categories encountered in the environment (e.g., race, age). Reliance on such norm-based coding appears to aid recognition, but few studies have examined the development of separable prototypes and the way in which experience influences the refinement of the coding dimensions associated with different face categories. The present dissertation was thus designed to investigate the organization and refinement of face space and the role of experience in shaping sensitivity to its underlying dimensions. In Study 1, I demonstrated that face space is organized with regard to norms that reflect face categories that are both visually and socially distinct. These results provide an indication of the types of category-specific prototypes that can conceivably exist in face space. Study 2 was designed to investigate whether children rely on category-specific prototypes and the extent to which experience facilitates the development of separable norms. I demonstrated that unlike adults and older children, 5-year-olds rely on a relatively undifferentiated face space, even for categories with which they receive ample experience. These results suggest that the dimensions of face space undergo significant refinement throughout childhood; 5 years of experience with a face category is not sufficient to facilitate the development of separable norms. In Studies 3 through 5, I examined how early and continuous exposure to young adult faces may optimize the face processing system for the dimensions of young relative to older adult faces. In Study 3, I found evidence for a young adult bias in attentional allocation among young and older adults. However, whereas young adults showed an own-age recognition advantage, older adults exhibited comparable recognition for young and older faces. These results suggest that despite the significant experience that older adults have with older faces, the early and continuous exposure they received with young faces continues to influence their recognition, perhaps because face space is optimized for young faces. In Studies 4 and 5, I examined whether sensitivity to deviations from the norm is superior for young relative to older adult faces. I used normality/attractiveness judgments as a measure of this sensitivity; to examine whether biases were specific to norm-based coding, I asked participants to discriminate between the same faces. Both young and older adults were more accurate when tested with young relative to older faces—but only when judging normality. Like adults, 3- and 7-year-olds were more accurate in judging the attractiveness of young faces; however, unlike adults, this bias extended to the discrimination task. Thus by 3 years of age children are more sensitive to differences among young relative to older faces, suggesting that young children's perceptual system is more finely tuned for young than older adult faces. Collectively, the results of this dissertation help elucidate the development of category-specific norms and clarify the role of experience in shaping sensitivity to the dimensions of face space.
    • Sleep and information processing in individuals who have sustained a traumatic brain injury

      Milner, Catherine; Department of Psychology (Brock University, 2011-05-17)
      Individuals who have sustained a traumatic brain injury (TBI) often complain of t roubl e sleeping and daytime fatigue but little is known about the neurophysiological underpinnings of the s e sleep difficulties. The fragile sleep of thos e with a TBI was predicted to be characterized by impairments in gating, hyperarousal and a breakdown in sleep homeostatic mechanisms. To test these hypotheses, 20 individuals with a TBI (18- 64 years old, 10 men) and 20 age-matched controls (18-61 years old, 9 men) took part in a comprehensive investigation of their sleep. While TBI participants were not recruited based on sleep complaint, the fmal sample was comprised of individuals with a variety of sleep complaints, across a range of injury severities. Rigorous screening procedures were used to reduce potential confounds (e.g., medication). Sleep and waking data were recorded with a 20-channel montage on three consecutive nights. Results showed dysregulation in sleep/wake mechanisms. The sleep of individuals with a TBI was less efficient than that of controls, as measured by sleep architecture variables. There was a clear breakdown in both spontaneous and evoked K-complexes in those with a TBI. Greater injury severities were associated with reductions in spindle density, though sleep spindles in slow wave sleep were longer for individuals with TBI than controls. Quantitative EEG revealed an impairment in sleep homeostatic mechanisms during sleep in the TBI group. As well, results showed the presence of hyper arousal based on quantitative EEG during sleep. In wakefulness, quantitative EEG showed a clear dissociation in arousal level between TBls with complaints of insomnia and TBls with daytime fatigue. In addition, ERPs indicated that the experience of hyper arousal in persons with a TBI was supported by neural evidence, particularly in wakefulness and Stage 2 sleep, and especially for those with insomnia symptoms. ERPs during sleep suggested that individuals with a TBI experienced impairments in information processing and sensory gating. Whereas neuropsychological testing and subjective data confirmed predicted deficits in the waking function of those with a TBI, particularly for those with more severe injuries, there were few group differences on laboratory computer-based tasks. Finally, the use of correlation analyses confirmed distinct sleep-wake relationships for each group. In sum, the mechanisms contributing to sleep disruption in TBI are particular to this condition, and unique neurobiological mechanisms predict the experience of insomnia versus daytime fatigue following a TBI. An understanding of how sleep becomes disrupted after a TBI is important to directing future research and neurorehabilitation.
    • Social Anxiety and Psychosocial Functioning: Investigating Relations Across Emerging Adulthood

      Brook, Christina; Department of Psychology
      The social, emotional and academic tasks associated with emerging adulthood are particularly challenging for those with social anxiety, a behavior defined as fear of negative evaluation, distress with social interactions, and/or avoidance of new or all social situations. The goal of this dissertation was to research the longitudinal effects of social anxiety on psychosocial functioning in university students, looking at various behaviors key to this developmental stage of life. In my first study, I examined the relation between social anxiety, social ties, and academic achievement in an autoregressive cross-lagged analysis across three years of university. There were two major findings: the symptoms of social anxiety directly linked to academic achievement, and social ties appeared to play a pivot role through their reciprocal negative and positive relation with social anxiety and academic achievement, respectively. Study two examined social anxiety with respect to alcohol use over three years of university through latent class growth analysis. Five classes were identified, two with social anxiety that differed in levels of alcohol use, and three with low social anxiety and varying levels of alcohol use. The heterogeneity in social anxiety was related to psychosocial functioning. While both social anxiety groups reported similar social anxiety symptomology, only the group linked to higher alcohol use exhibited a greater vulnerability to other at-risk behaviors in year one (e.g., self injury). The third study followed the previously identified five groups through latent growth analysis for a total of seven years, to determine whether there was stability or change in psychosocial functioning over the long term. The results indicated that there was stability within and among groups across time in psychosocial functioning. Notably, the differences detected between the two social anxiety groups in year one continued over the long term, indicating that the at-risk behaviors associated with the social anxiety group reporting higher alcohol use persisted. Overall, this program of research revealed that those with social anxiety in university struggled more than their peers in a variety of domains. From a developmental perspective, the findings of stability in behavior suggested it might be important for intervention and prevention programs to target younger populations with strategies that are continued in a cohesive manner across university, a time when students are exposed to the pressures of achieving in competing developmental tasks.
    • Social neuroendocrinology of competition

      Carré, Justin M.; Department of Psychology (Brock University, 2010-10-26)
      The relationship between testosterone concentrations and aggressive behaviour in studies of people has produced very inconsistent findings. However, one consistent fmding that has emerged is that competitive and aggressive interactions potentiate testosterone release in both human and non-human species. It has been argued that socially-induced alterations in testosterone concentrations may function to influence ongoing and/or future social behaviour. Nonetheless, few studies have empirically tested this hypothesis. The current series of experiments was designed to address the extent to which competitioninduced fluctuations in testosterone concentrations were associated with ongoing and/or subsequent social behaviour. In Study 1, men (n = 38) provided saliva samples prior to, and at the conclusion of, the Point Subtraction Aggression Paradigm (PSAP). Although baseline testosterone concentrations were not related to aggressive behaviour, there was a positive correlation between change in testosterone and aggressive behaviour such that men who were most aggressive on the PSAP demonstrated the largest increase in testosterone concentrations. Furthermore, a rise in testosterone during the PSAP predicted willingness to choose a subsequent competitive task. In Study 2, men and women provided saliva samples prior to and after competing against a same-sex opponent on the Number Tracing Task (NTT). The outcome of the competition was rigged such that half of the individuals won most of the races, while the other half lost most of the races, thus experimentally creating a winner and loser in the laboratory. Following the competitive interaction, men and women played the PSAP with their same-sex partner. Results indicated that men selected the aggressive response (but not reward or protection responses), more frequently than women. For men assigned to the loss condition, an increase in testosterone concentrations in response to the NTT predicted subsequent aggressive behaviour. For men assigned to the win condition, an increase in testosterone concentrations in response to the NTT predicted subsequent aggressive behaviour, but only among those men who scored high on trait dominance. Change in testosterone and trait dominance did not predict aggressive behaviour in women. In Study 3, men provided saliva samples prior to, during, and at the end of the PSAP. They were randomly assigned to one of four experimental conditions that differed in the extent to which they were provoked and whether they received reward for behaving aggressively (i.e., stealing points). Results indicated that baseline testosterone concentrations did not correlate with aggression in any of the experimental conditions. Consistent with Study 1, there was a positive correlation between change in testosterone and aggressive behaviour among men who were provoked, but did not receive reward for aggression (i.e., reactive condition). Men who were provoked but did not receive reward for aggression enjoyed the task the most and were more likely to choose the competitive versus non-competitive task relative to men assigned to the other experimental conditions. Also, individual differences in aggressive behaviour among these men were positively correlated with the extent to which they enjoyed the task. Together, these studies indicate that testosterone dynamics within the context of competition influence subsequent competitive and aggressive behaviours in humans and that testosterone may be a marker of the intrinsically rewarding nature of costly aggressive behaviour.
    • Testing a Hypothesis of Non-REM Sleep Reinforcement and REM Sleep Refinement for the Benefits of Post-Learning Sleep on Memory Retrieval

      MacDonald, Kevin John; Department of Psychology
      It is well established that post-learning sleep benefits later memory retrieval, but there is still much to learn about the processes involved and the nature of these benefits. Sleep is composed of stages of non-REM (NREM) and REM sleep: NREM sleep, especially slow wave activity of NREM sleep, and REM sleep have been implicated in memory performance benefits, but the specific contributions of each state remain unclear. This thesis presents a hypothesis proposing that post-learning NREM sleep supports memory accessibility, benefitting the likelihood of successful memory retrieval, and that post-learning REM sleep supports memory fidelity, allowing for more accurate retrieval when retrieval is successful. This hypothesis was tested over studies examining the effects of an afternoon nap (Chapter 2), targeted memory reactivation during NREM slow wave sleep (Chapter 3), and both targeted memory reactivation during NREM slow wave sleep and selective deprivation of REM sleep (Chapter 4) on measures of memory accessibility and memory fidelity in visuospatial memory tasks. In each study, measures of sleep architecture and electroencephalographic power in sleep were examined as predictors of memory performance. Several identified associations and interactions further inform an understanding of how NREM sleep and REM sleep may benefit memory performance. Most notably, these studies consistently found greater slow wave activity of NREM sleep to be specifically associated with better maintenance of memory accessibility. These studies did not identify a clear effect of REM sleep. It is hoped that the hypothesis and findings presented stimulate additional inquires that will further our understanding of the individual and combined contributions of NREM and REM sleep.
    • Top-down and Bottom-up influences on ACC activation: Evaluation of a proposed model of the feedback-related negativity

      Dzyundzyak, Angela; Department of Psychology (Brock University, 2014-07-18)
      The Feedback-Related Negativity (FRN) is thought to reflect the dopaminergic prediction error signal from the subcortical areas to the ACC (i.e., a bottom-up signal). Two studies were conducted in order to test a new model of FRN generation, which includes direct modulating influences of medial PFC (i.e., top-down signals) on the ACC at the time of the FRN. Study 1 examined the effects of one’s sense of control (top-down) and of informative cues (bottom-up) on the FRN measures. In Study 2, sense of control and instruction-based (top-down) and probability-based expectations (bottom-up) were manipulated to test the proposed model. The results suggest that any influences of medial PFC on the activity of the ACC that occur in the context of incentive tasks are not direct. The FRN was shown to be sensitive to salient stimulus characteristics. The results of this dissertation partially support the reinforcement learning theory, in that the FRN is a marker for prediction error signal from subcortical areas. However, the pattern of results outlined here suggests that prediction errors are based on salient stimulus characteristics and are not reward specific. A second goal of this dissertation was to examine whether ACC activity, measured through the FRN, is altered in individuals at-risk for problem-gambling behaviour (PG). Individuals in this group were more sensitive to the valence of the outcome in a gambling task compared to not at-risk individuals, suggesting that gambling contexts increase the sensitivity of the reward system to valence of the outcome in individuals at risk for PG. Furthermore, at-risk participants showed an increased sensitivity to reward characteristics and a decreased response to loss outcomes. This contrasts with those not at risk whose FRNs were sensitive to losses. As the results did not replicate previous research showing attenuated FRNs in pathological gamblers, it is likely that the size and time of the FRN does not change gradually with increasing risk of maladaptive behaviour. Instead, changes in ACC activity reflected by the FRN in general can be observed only after behaviour becomes clinically maladaptive or through comparison between different types of gain/loss outcomes.