Social anxiety disorder (SAD) is characterized by an intense fear of negative evaluation from others in social and/or performance situations. Research has demonstrated that socially anxious individuals' post-event processing, or post-mortem review of social situations, often affects their levels of anxiety, negative emotions, interpretations, and memories of events (Brozovich & Heimberg, 2008). Furthermore, research has shown that processing negative descriptions using imagery is more emotion-evoking than semantic processing of the same material (Holmes & Mathews, 2005; Holmes & Mathews, 2010). The present study investigated post-event processing involving mental imagery and its effects on mood, anxiety, and potentially biased interpretations of social and nonsocial events. Socially anxious and non-anxious participants were told they would give a 5 min impromptu speech at the end of the experimental session. They were then randomly assigned to one of three manipulation conditions: post-event processing imagery (PEP-Imagery), post-event processing semantic (PEP-Semantic), or a Control condition. In the post-event processing conditions, participants recalled a past anxiety-provoking speech and thought about the anticipated speech either using imagery (PEP-Imagery) or focusing on their meaning (PEP-Semantic). Following the condition manipulation, participants completed a variety of affect, anxiety, and interpretation measures. Consistent with our predictions, socially anxious individuals in the PEP-Imagery condition displayed greater anxiety than individuals in the other conditions immediately following the induction and before the anticipated speech task. Socially anxious individuals in the PEP-Imagery condition also interpreted ambiguous scenarios in a more socially anxious manner than individuals in the Control condition. The impact of imagery during post-event processing in social anxiety and its implications for cognitive-behavioral interventions are discussed. / Psychology

Person-environment interactions are the rule, not only for development but also for moment-to-moment experience. Knowledge about environmental influences on the manifestation of psychological symptoms is an important area of research, particularly with regard to social anxiety where symptoms vary dramatically depending on the social context. Like other forms of anxiety, social anxiety is thought to have evolved to help us pay attention to, assess, and respond to potential (in this case, intra-species) threats. The current study was based on (1) the theoretical proposition that social anxiety represents an adaptation to hierarchical, or agonic, modes of social organization; (2) the observation that in the non-hierarchical hedonic systems seen in some of our closest primate relatives, submissiveness is not required for group functioning, and (3) more recent empirical data showing that social anxiety symptoms are dependent on contextual factors. The current study integrated these three ideas and examined whether participating in a hedonic system, as compared to an agonic system, diminishes social anxiety, and whether social context moderates the relationship between trait social anxiety and activation of state anxiety. Participants of all different levels of trait social anxiety were randomly assigned to play a group game, the context and rules of which were consistent with either agonic or hedonic social structures. Self-reported anxiety and behaviors associated with social anxiety were then measured. Results from the experiment were mixed, sometimes seemingly conflicting, and therefore difficult to interpret. The more hierarchical, agonic social system was associated with higher anxious affect. However, the type of social system did not appear to affect self-reported submissive behavior, social comparison, or social behavior. Additionally, experimental condition did not moderate the effect of trait social anxiety on these variables. Although our findings were mixed, they hint at the role of social structure in the activation of anxious affect. / Psychology

Individuals with social anxiety have been shown to have higher levels of friendship impairment and greater difficulty establishing close relationships than persons without social anxiety. However, the mechanisms associated with such impairment have not been widely examined. Previous research suggests that deficiencies in prosocial behaviors (e.g., low warmth, limited self-disclosure, and constrained cooperation) during interpersonal exchanges may partially explain their difficulties developing close relationships. The present study aimed to examine the effect that rejection may have on prosocial behaviors, as well as other factors associated with developing and maintaining friendships, including trust, perceived likeability, closeness/connectedness, using an iterated, computerized version of the Prisoner’s Dilemma (PD) game. Participants with high (n = 56) and low (n = 35) social anxiety were asked to play the PD game with another participant (actually an experimental confederate) whom they met at the start of the study. Participants were led to believe that they were playing the PD game against the other participant but were actually playing against a computer that was programmed with a strategy meant to initially facilitate cooperation. Cooperation, or giving, in the PD game was measured primarily by the number of tokens that the participant shared with his/her partner. Additionally, participants were randomized to either rejection or non-rejection conditions. Partway through the study, those in the rejection condition were exposed to a programmed decrease in giving by their partner as well as an ambiguous in-person rejection (administered by the experimenter). Participants in the non-rejection condition were not exposed to either the programmed or in-person manipulations. Outcomes of interest included total giving during the PD game, constriction of giving, and the use of particular strategies following rejection in the PD game, as well as various measures of relationship quality collected at the end of each round of play. It was hypothesized that individuals with high social anxiety in the rejection condition would exhibit less total giving and a constricted response to low partner giving and also be less likely to use prosocial strategies to encourage cooperation (i.e., a coaxing strategy) following rejection by the partner compared to those with low social anxiety in the rejection condition. Additionally, we anticipated that those with high social anxiety in the rejection condition would provide lower ratings of the following relationship quality domains following the rejection condition: trust, closeness/connectedness, and perceived likeability than those with low social anxiety in the rejection condition. Overall, results provided little support for these hypotheses. However, there were several significant main effects that highlighted differences among those with high and low social anxiety. For example, individuals with high social anxiety had greater ratings of the expectancy of future rejection and of the importance of their next turn for maintaining the quality of their relationship with their partner. Additionally, there was a trend level (p = .08) social anxiety group by rejection condition interaction on the participant’s trust of his/her partner, such that those with high social anxiety exhibited reductions in relationship trust following rejection whereas those with low social anxiety did not. Implications of these findings as well as limitations and future directions of study are also explored. / Psychology

Heavy drinking has been consistently associated with negative legal, academic, and health problems in college students and recent studies suggest that the frequency of undergraduates experiencing alcohol related problems may be increasing. Research aimed at lowering rates of consumption has begun to focus on individual differences in motivations for heavy alcohol use. The following study used a social-cognitive based model to prospectively examine heavy drinking among socially anxious college students. It was hypothesized that alcohol expectancies of social facilitation/anxiety reduction and self-efficacy for avoiding heavy drinking in socially anxious situations would be predictive of drinking in socially anxious college students. Using group testing and individual interview formats questionnaires assessing alcohol expectancies of improved sociability and self-efficacy were developed and shown to have adequate levels of reliability and construct validity. These questionnaires, along with measures of dispositional social anxiety, and a quantity-frequency index of alcohol use were then administered to 372 undergraduates. Seventy-one participants, identified as dispositionally socially anxious, were followed-up six-weeks later and completed both a time-line-follow-back assessment of their alcohol use over the six week interval and a semi-structured interview that assessed the types of situations in which they drank. Results of the study provided partial support for the hypothesized model as the expectancy X efficacy interaction accounted for a significant percentage of the variance in the quantity and frequency of alcohol use after controlling for the main effects of alcohol expectancies and self-efficacy. At the six-week follow-up however, the expectancy X efficacy interaction failed to account for significant variance beyond that accounted for by the expectancy and efficacy effects. Further examination of the follow-up data did provide partial support for the model, as it was found that the main effects of expectancy and efficacy were significant predictors of drinking behavior, but only in situations that were likely to elicit feelings of social anxiety. Results are discussed in terms of the relationship between social anxiety, outcome expectancies and self-efficacy and implications for developing alcohol intervention programs with high-risk college student drinkers. / Ph. D.

The present study aimed to: (1) Characterize markers of reward sensitivity during periods of social stress using a well validated social feedback paradigm; (2) Evaluate clinical relations between reward markers and anhedonia; and (3) Investigate if elevated levels of baseline prior exposure to stress (i.e., peer victimization) are associated with the degree of ventral striatum suppression and anhedonia symptoms in a social stress context. A total of 29 adolescents between the ages of 13 and 17 years old (Mage = 15.31; SD = 1.51; 55.2% cisgender girls) participated in the present study. Participants were asked to complete a semi-structured interview; fill out self-report questionnaires regarding social anxiety, stress, depression, and anhedonia; and complete a magnetic resonance imaging scan while playing the Island Getaway task. Ventral striatum (VS) BOLD signal activation estimates were then extracted during discrete phases of the game (e.g., anticipation of social feedback and outcome of social feedback) and statistically compared within-subjects via paired samples t-tests and correlated to social anxiety measures. Additionally, regression analyses assessed the effect of VS activation on anhedonia as well as the associative effect of peer victimization on VS activation and anhedonia. Results revealed that when in the presence of social stress (defined as the potential for negative feedback), socially anxious adolescents demonstrated significantly suppressed VS activation relative to baseline when anticipating feedback. Additionally, results indicated that the degree of reduced VS activation during anticipation was correlated to total changes in anhedonia severity across the task. Lastly, results demonstrated that overt peer victimization is a significant predictor of suppressed VS activation during anticipation of social feedback, but not during social outcomes. Taken together, these results identify potentially novel mechanisms associated with anhedonia and blunted reward processing in socially anxious youth that could be improved via interventions that target positive-valence systems. / Doctor of Philosophy / Socially anxious teens may be at a heightened risk for developing anhedonia – which means that they are showing a significant lack of interest in things they used to find interesting or rewarding. This is problematic, because the presence of anhedonia is associated with not doing as well in therapy and even with higher rates of suicide attempt. One area that may be linked to the development of anhedonia in socially anxious teens is social stress induced disrupted reward processing in certain regions of the brain that generally activate when people anticipate a reward. Despite this, there is very little research on the development of anhedonia is socially anxious teens and even less that focuses on biological and behavioral experiences of reward processing when under social stress. This study examines this potential stress-to-anhedonia pipeline by looking at a key region of the brain, called the ventral striatum, to see if social stress does disrupt reward processing in socially anxious teens, and, if so, if this disrupted reward processing is related to anhedonia. Through evaluating a total of 29 socially anxious teens who underwent a social stress task while completing brain scanning, the present study demonstrated evidence for diminished brain activation in the ventral striatum when anticipating rewards. Additionally, the present study showed that reduced brain activation in the ventral striatum was associated with changes in anhedonia severity. Lastly, results from this study indicated that peer victimization (or bullying) was a significant predictor of diminished brain activation in the ventral striatum. Taken together, these results identify potentially new markers associated with anhedonia and blunted reward processing in socially anxious youth that could be improved via interventions.

Social Anxiety (SAD) increases in prevalence as children enter adolescence. Adolescents with Autism Spectrum Disorder (ASD) are diagnosed with comorbid SAD at higher rates than these individuals are diagnosed with other clinical disorders, including depression and other anxiety disorders. However, there is little research on whether the presentation and neural underpinning of comorbid SAD within the context of ASD is the same as SAD alone. Individual and diagnostic differences exist in neural and biological mechanisms of fear conditioning. Characterization of whether neural mechanisms of fear are different within ASD with comorbid SAD and SAD alone may better inform clinical treatments. Accordingly, the present study characterizes neural responses during a fear-inducing experiment, as measured by fMRI. Fifty-seven adolescents participated in this study, with adolescents with ASD and SAD (n=17), SAD alone (n=20), and typically developing adolescents (n=20). All participants completed two fear conditioning and reversal paradigms while completing an fMRI scan. The paradigm consisted of a Social condition and Nonsocial condition. An ANOVA for fear conditioning was conducted. Results revealed significant activation in the Inferior Temporal Gyrus (ITG) during fear conditioning. No between group differences were observed, but within-group differences indicated differential modulation of the ITG in the ASD with SAD group in the Social condition compared to the Nonsocial condition. The SAD group demonstrated differential activation between conditioning stimuli in the Nonsocial condition, but not in the Social condition. Results indicate that adolescents with ASD and SAD may display different neural mechanisms for acquiring fear compared to typically developing peers. Results have potential to inform treatment approaches. / Doctor of Philosophy / Based on the 2012 international energy agency (IEA) report, global waste heat energy is estimated to be in the range of 246 Exajoule (1 EJ = 10¹⁸ J). Tapping even small fraction of this wasted energy through thermal energy harvesting techniques will allow us to generate significant magnitude of green energy. Thermoelectrics (TEs) are one of the most promising thermal energy conversion materials as they offer cost-effective and environmentally friendly option with solid-state silent operation and scalability. Among many different options for high temperature TE materials, half-Heusler system is one of the leading candidates as it has the potential to provide high performance and thermal stability at temperatures as high as 873 K. The progress in developing practical half-Heusler materials has been limited for last two decades. Despite many publications, the maximum figure of merit (zT) of n-type half-Heusler materials has been stagnant (zT ~ 1.0). Further, there has been a lack of focus towards module development that can operate under realistic conditions. This dissertation provides comprehensive studies on novel thermoelectric compositions and nanocomposites that are suitable for manufacturing of high temperature modules. Microstructural architectures proposed here provide the ability to tailor electronic transport and phonon scattering beyond the commonly demonstrated regimes. Optimized materials were successfully implemented in efficient and stable thermoelectric generator exhibiting power density on the order of 13.81 W⸱cm⁻² , which is 1400 % higher than that of the fuel cell (~1 W⸱cm⁻² ).

Social Anxiety Disorder (SAD) is characterized by excessive concern or fear of negative evaluation in one or more social situations and ranks as one of the most common psychiatric disorders. SAD has also been characterized by significant deficits in social motivation and a lack of reactivity to pleasurable stimuli (i.e., positive affect; [PA]), particularly within social contexts. Recent neuroimaging work has shifted towards examining positively-valenced motivational systems in SAD focused on reward responses to social and nonsocial stimuli. These studies have revealed aberrant reward processing during social reward tasks in individuals with SAD. However, not all individuals with SAD exhibit reward circuitry dysfunction. Therefore, the current study aimed to examine if functional patterns of connectivity in the brain underlie heterogeneity in PA differences in individuals with SAD. Results revealed several functional connectivity strength differences between SAD and control groups within reward regions. Additionally, associations between regions of interest (ROIs)-couplings (i.e., OFC and insula, OFC and subgenual cingulate, insula and cingulate, and cingulate and subgenual cingulate) and diminished PA were present in individuals with SAD, but not controls. Lastly, results demonstrated that individuals with SAD had higher variability in their reward connectivity strength presentations and reports of PA as compared to controls. These results hold significance for the development of interventions for SAD that focus on the enhancement of PA to bolster social reward responsivity. / M.S. / Social Anxiety Disorder (SAD) is a common disorder where individuals experience persistent excessive fear of one or more social situations. Individuals with SAD also tend to show lower social motivation and a lack of reactivity to pleasurable activities/events (referred to broadly as positive affect; [PA]), particularly within social situations. Current work has focused on areas within the brain that are responsible for reward responses, and have indicated that individuals with SAD show different types of reward processing during social reward situations. However, not all individuals with SAD show these same patterns. Therefore, the current study aimed to examine if connections between reward regions in the brain underlie differences in PA differences in individuals with SAD. Results showed several differences between SAD and control groups within reward regions of the brain. Additionally, specific associations between brain regions of interest and low PA were present in individuals with SAD, but not controls. Lastly, results demonstrated that individuals with SAD had higher variability in their connections between reward regions and reports of PA as compared to controls. These results can help inform the development of treatments for SAD that focus on the improving PA in an attempt to increase responsiveness to social rewards.

The broad autism phenotype (BAP) has been defined both behaviorally and biologically. There has been little research on the association of the BAP, behaviorally defined, with neural or cognitive biomarkers typically associated with Autism Spectrum Disorder (ASD). People diagnosed with ASD tend to show reduced gaze fixation toward the eye region, but much less eye-tracking research has been done related to the BAP (Boraston & Blakemore, 2007). In this study, we sought to assess eye gaze patterns in people with the behaviorally defined BAP, as defined by a score of 30 or above on the Autism Spectrum Quotient (AQ; Baron-Cohen et al., 2001). It was hypothesized that the BAP group participants would exhibit longer average fixation duration to the eye region during an emotion recognition condition, relative to a free-viewing condition, whereas the comparison group participants (defined as an AQ score of 24 and below) would not show a difference in fixation duration to the eye region between conditions. Nine hundred and thirty-nine undergraduates completed an online survey, and 45 of these students (15 BAP group and 30 comparison group) participated in the eye-tracking session, where they viewed a series of human faces, each presented twice within a condition. Results revealed a significant negative relationship between social anxiety and eye region fixation duration in the free-viewing condition, for both presentations of faces. Contrary to expectation, BAP predicted longer eye region fixation duration in the free-viewing condition, for the second presentation of faces. Possible explanations for these surprising findings are discussed. / Master of Science

The clinical presentation of social phobia suggests that alterations in theory of mind (TOM) may play a systematic role in the development and maintenance of the disorder. In the current study we leverage a quantitative neuroeconmic approach to probe for neural and behavior markers of cognitive TOM, as well as rejection estimation, with a particular focus on social phobia. Participants comprised a non-clinical sample that was divided into low (N = 10) and high (N = 7) social anxiety groups based on self-report. Participants completed a one-sided uncertainty ultimatum game designed to probe individual differences in cognitive TOM, as well as rejection estimation. Contrary to predictions, there were no behavioral differences between high and low social anxiety groups in terms of rejection estimation. Although no between-group differences emerged in the traditional TOM network, significant differences were observed in subregions of the striatum during formulation of offers, likely corresponding to estimation of reward expectations. As hypothesized, and consistent with past research, imaging results support the existence of a network regions implicated in TOM, including the medial prefrontal cortex (MPFC) and the temporal parietal junction (TPJ). In addition to these regions, additional areas, including the caudate and insula, were also active during mentalizing components of the task. Collectively, results suggest a novel role for expected-value computations in the development and maintenance of social phobia. / Master of Science

The role of children’s emotion regulation as a potential mediator or moderator in the relations between a family’s emotional expressiveness and their child’s social anxiety was explored in a sample of clinic-referred children. For the mediational analyses, it was predicted that emotional expressivity in families would be associated with social anxiety and that this relationship would be mediated by emotion regulation. For the moderator analyses, it was predicted that the level of emotion regulation would affect the strength of the relationship between emotional expressivity in families and social anxiety. The hypotheses were explored through hierarchical regression analyses. Family expressivity was marginally related to social anxiety. However, exploratory analyses indicated that emotion regulation failed to mediate or moderate this marginal relationship. Interestingly, mother reports of expressivity were related negatively to social anxiety whereas father reports of expressivity were related positively to social anxiety in their offspring. These findings are discussed and their implications are explored. / Master of Science