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<p>Event-related potentials (ERPs) have been used extensively in the scientific research of cognitive processing such as language comprehension. Specific responses, such as the negativity called N400 (Kutas & Hillyard, 1980), have in the literature typically been associated with semantic violations in sentences. Another electrophysiological response, the positive P600 waveform, has mostly been associated with syntactic and morphological violations. However, recently, the P600 has been reported also in connection with semantic violations (Kuperberg et al, 2003; van Herten, 2004; Osterhout, 2004). The present research further explores the neurophysiological correlates of processing sentences with semantic and morpho-syntactic violations. It tests the functional interpretations of the P600 component, which has been proposed to reflect syntactic error detection, context updating, or syntactic reanalysis or repair. I contrasted semantic and syntactic possessive violations. The semantic violation conditions (i.e. <em>The mother borrowed the <strong>car’s daughter</strong> for work yesterday</em>), morphosyntactic violations (i.e. <em>The mother borrowed the <strong>daughter car</strong> for work yesterday) </em>and double violation sentences (i.e. <em>The mother borrowed the <strong>car daughter</strong> for work yesterday) </em>were derived from the control condition, (i.e. <em>The mother borrowed the <strong>daughter’s car</strong> for work yesterday). </em>I explored whether the P600 component may index more general processes than ones related to syntactic error detection. An N400 was seen to our semantic manipulation, i.e. <em>The mother borrowed the <strong>car’s daughter</strong> for work yesterday.</em> However, none of the conditions produced a P600.</p> / Master of Science (MSc)

Shyness is a personality trait that is stable across time and situations in some individuals. While childhood shyness is a risk factor for later mental health and emotional problems, not all shy children grow up to have these problems. This thesis examined subtypes of shyness identified based on the temporal stability of shyness and based on levels of sociability and their corresponding outcomes, as well as the roles of social and biological contextual factors. Chapters 2-4 comprise the empirical studies. In Chapter 2, I report three shyness trajectories from middle childhood to adulthood (ages 8 to 30-35). Relative to a low-stable non-shy trajectory, children with an increasing, but not a decreasing, shy trajectory were at higher risk for clinically significant social anxiety, depression, and substance use, and were hypervigilant to angry faces in adulthood. Chapters 3 and 4 then report electrocortical correlates and mechanisms during the processing of non-social auditory novelty and social exclusion across children, adolescents, and adults with varying levels of shyness and sociability. Chapter 3 established that shyness, but not sociability, was related to the P300 ERP in processing non-social auditory stimuli in both 10-year-old children and adults, in support of the notion that shyness and sociability are independent personality dimensions. Findings on subtypes of shyness also showed that children characterized by conflicted shyness (with high levels of both shyness and sociability) reported higher neuroticism, but this relation was mediated by increased P300 amplitudes to processing background stimuli. Finally, Chapter 4 reports that individuals characterized by conflicted shyness who exhibited high theta EEG spectral power to social exclusion were most fearful of negative evaluation, irrespective of age. Also, conflicted shy adolescents who showed high theta spectral power to social exclusion were most likely to engage in substance-use. These findings highlight that there is much heterogeneity in shyness, and that shyness is not directly related to adverse mental health outcomes. / Thesis / Doctor of Philosophy (PhD) / Shyness is a personality trait that is stable across time and situations in some individuals. Past research suggests that shy children exhibit more internalizing problems, including anxiety and depression, compared to their non-shy counterparts. However, the development of shyness has not been studied beyond adolescence, and the biological and social factors that contribute to adverse developmental pathways and outcomes related to shyness are not well understood. The goal of this thesis was to understand the mental health outcomes of shy individuals by examining different subtypes of shy individuals. To this end, this thesis first demonstrated how shyness unfolds across the first four decades of life to shape adult mental health outcomes in a cohort of individuals. Second, this thesis examined how neural responses to threatening social and non-social contexts related to the socioemotional outcomes across children, adolescents and adults with varying levels of shyness.

Yes / The processing of notes and chords which are harmonically incongruous with their context has been shown to elicit two distinct late ERP effects. These effects strongly resemble two effects associated with the processing of linguistic incongruities: a P600, resembling a typical response to syntactic incongruities in language, and an N500, evocative of the N400, which is typically elicited in response to semantic incongruities in language. Despite the robustness of these two patterns in the musical incongruity literature, no consensus has yet been reached as to the reasons for the existence of two distinct responses to harmonic incongruities. This study was the first to use behavioural and ERP data to test two possible explanations for the existence of these two patterns: the musicianship of listeners, and the resolved or unresolved nature of the harmonic incongruities. Results showed that harmonically incongruous notes and chords elicited a late positivity similar to the P600 when they were embedded within sequences which started and ended in the same key (harmonically resolved). The notes and chords which indicated that there would be no return to the original key (leaving the piece harmonically unresolved) were associated with a further P600 in musicians, but with a negativity resembling the N500 in non-musicians. We suggest that the late positivity reflects the conscious perception of a specific element as being incongruous with its context and the efforts of musicians to integrate the harmonic incongruity into its local context as a result of their analytic listening style, while the late negativity reflects the detection of the absence of resolution in non-musicians as a result of their holistic listening style.

Many methodologies have been used to generate false memories, with the misinformation (MI) paradigm and the Deese-Roediger-McDermott (DRM) paradigm being the most commonly studied. The MI paradigm generates false memories based on retroactive interference across episodes, while the DRM paradigm generates false memories based on semantic similarities across stimuli. Since current research is ambiguous about whether the processes for different types of false memories are similar, the purpose of this project was to compare the neural mechanisms between MI and DRM false memories. We used a novel paradigm to limit methodological differences, while maintaining the defining characteristics of each paradigm. We made ERP predictions for false memories in both paradigms based on four current cognitive theories of false memories: fuzzy-trace theory, spreading activation/monitoring theory, global matching models, and source of activation confusion (SAC) model. We found no LPC, FN400, or N2 neural differences between the two types of false memories. This result is discussed in the context of the theories and the implications about our understanding of false memories. Our results support that there may not be mechanistic differences in false memory recollection when paradigms to produce the false memories are similar. / Ph. D. / Many methodologies have been used to generate false memories (or retrieval of an incorrect detail of an experienced event), with the misinformation (MI) paradigm and the Deese-Roediger-McDermott (DRM) paradigm being the most commonly studied. The MI paradigm generates false memories based on incorrectly described details provided by the experimenter across episodes, while the DRM paradigm generates false memories based on semantic similarities across lists of words. Since current research is ambiguous about whether the processes for different types of false memories are similar, the purpose of this project was to compare the MI and DRM false memories. We used a novel paradigm to limit differences driven by different methods, while maintaining the defining characteristics of each paradigm. The four current memory theories informed our event-related potential (time-locked electroencephalogram) predictions. The four theories are fuzzy-trace theory, spreading activation/monitoring theory, global matching models, and source of activation confusion (SAC) model. We found no late positive component (an ERP component indicating recollective processes), FN400 (an ERP component indicating familiarity processes), or N2 (an ERP component indicating conflict) differences between the two types of false memories. This result is discussed in the context of these theories and the implications about our understanding of false memories. Our results support that there may not be differences in false memory recollection when paradigms to produce the false memories are similar.

Evidence for differences between assigned female at birth (AFAB) and assigned male at birth (AMAB) perceiving, processing, and evaluating infant faces has been mixed. The current study examined whether expected parental self-efficacy (EPSE) and desire for children predicts event-related potentials (ERPs) to infant facial affect in potential parents. No scale for EPSE exists. Therefore, we reworded the Perceived Maternal Parental Self-Efficacy scale from present to future tense. There was no correlation with EPSE scores, ERPs, or behavioral data. No difference was found between AFAB and AMAB in accurately evaluating infant faces; however, AFABs responded more quickly. ERP data revealed significantly higher P300 amplitude for AFAB participants. Peak-to-peak P100/N170 was significantly higher for negative affect stimuli. However, peak-to-peak P100/N170 amplitude showed no difference between AFAB and AMAB. The results of the study suggest sex differences exist, but what is driving those differences may be more than just evolutionary beneficial specialization

Reward-based learning is the ability to alter our future behavior following a novel reward. Dysregulation in this system has been linked to different forms of adult and pediatric psychopathologies such as mood disorders, for which it has proved to be an important treatment target given its link to broader health outcomes for these disorders. However, more research is needed to better understand its underlying mechanisms in the pediatric population. The current study examined how probabilistic reward learning, feedback-related negativity (FRN; an event-related potential from EEG), and dimensional ADHD symptom severity relate in adolescents with prominent mood symptoms. The final sample included 36 adolescents (72.2% female; aged 13 to 17) who completed a Probabilistic Reward Task (PRT) during EEG recording. Results revealed an inverse relationship between FRN mean amplitude and the reward learning score, independent of mood and ADHD symptoms. We also found that teens with increased overall ADHD symptom severity showed a larger (i.e., more negative voltage) FRN amplitude and a lower reward learning score. Exploratory analyses also showed that as ADHD inattentive symptom severity increased, FRN mean amplitude became more negative and reward learning score decreased. No significant relationship was found with ADHD hyperactive/impulsive symptom severity. In conclusion, our results showed that a poor modulation of behavior based on prior reward contingencies was related to an increase in dimensional ADHD symptom severity in a sample of adolescents with prominent mood difficulties. This behavioral dysfunction was also reflected by a blunted neural habituation to reward feedback as evidenced by a larger FRN mean amplitude. Additionally, exploratory analyses highlighted how the relationship between overall ADHD symptom severity and FRN may be driven especially by symptoms of inattention vs. hyperactivity/impulsivity. Results suggest deficits in reward learning that could impact response to behavioral therapies in youth with mood disorders and comorbid inattentive ADHD.