Graduate Theses & Dissertations

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Social Communicative Factors as Predictors of Symptom Severity in Autism Spectrum Disorders
Early diagnosis of autism spectrum disorder (ASD), while providing many benefits, presents challenges to clinicians such as predicting the stability of symptoms. Accurately predicting symptom severity allows clinicians to confidently diagnose and assign the most appropriate treatment. Little research exists to date to predict symptom severity in children with ASD who have not been exposed to treatment. The present file review examined prelinguistic skills as predictors of symptom severity in a group of young children (age: 18 – 64 months) with ASD (n = 199) who had not been exposed to significant levels of treatment. Hierarchical regression analyses demonstrated that of the two core diagnostic features (social communicative deficits and restricted repetitive behaviours), social communicative skills best predicted symptom severity. Furthermore, social communicative gestures predicted symptom severity after age, adaptive behaviour, restricted repetitive behaviours, and functional gestures had been accounted for. Author Keywords: autism, gestures, predictors, prelinguistic, social communicative, symptom severity
Model for the Differential Susceptibility of Strontium Titanate
The appearance of a two-dimensional electron gas (2DEG) in oxide interfaces between strontium titanate (STO) and other materials has become a major area of study. The behaviour of the 2DEG in STO is not well understood in part because the dielectric properties of STO are not well characterized. The differential susceptibility has a major impact on the electric fields within strontium titanate, and therefore to understand the 2DEG a better understanding of the susceptibility is needed. An expression for the soft mode phonon frequency of bulk strontium titanate is derived and used to model the susceptibility as a function of spatially homogeneous electric field, temperature and wavevector. This model is used to discuss the effect of spatially inhomogeneous electric fields and the local vs. nonlocal nature of the susceptibility. The critical exponents and the free energy are determined and discussed. Author Keywords: critical exponents, differential susceptibility, quantum paraelectric, strontium titanate
Genetic diversity and differentiation of Ontario’s recolonizing fishers (Pekania pennanti)
Fishers (Pekania pennanti) were extirpated from many parts of Ontario in the early 20th century, but as of the early 2000s the species had recolonized most of its historical range. While the primary population genetic structure of fishers in central and eastern Ontario has not changed drastically over the past ten years, we did find evidence of increased secondary structure and a reduction in northward movement from southeastern Ontario, a site of recent immigration from the Adirondacks in northern New York. This may be indicative of a reduction in density and thus in density-dependent migration, or it may be a consequence of the population reaching equilibrium following a period of rapid expansion associated with recolonization. We also observed no variation within central and eastern Ontario at 14 of 15 candidate functional loci we screened, suggesting possible directional or stabilizing selection and a lack of adaptive potential. Author Keywords: fisher, functional genes, Ontario, Pekania pennanti, population genetics, recolonization
Cognitive and Affective Theory of Mind in Children and Young Adolescents
Recently, a distinction has been made between cognitive theory of mind, the ability to make inferences about other's beliefs and thoughts, and affective theory of mind, the ability to make inferences about other's emotional states. The purpose of this study is to determine if the distinction between cognitive and affective theory of mind is developmentally appropriate and whether the relation between language and theory of mind is maintained when cognitive and affective theory of mind are examined separately. The sample consisted of 20 children aged 6 to 9 years, and 27 children aged 11 to 15 years. Results showed that the older group outperformed the younger group on both cognitive and affective theory of mind, and that different aspects of language were related to each type of theory of mind. This suggests the distinction between cognitive and affective theory of mind may in fact be valid in this age range. Author Keywords: Affective Theory of Mind, Cognitive Theory of Mind, Development, Language
Non-Hippocampal Memory Systems Contributing to Reinstated Context Memory
Damage to the hippocampus (HPC) typically causes retrograde amnesia for contextual fear conditioning. Reinstating the conditioning over several sessions, however, can mitigate the retrograde amnesic effects. Reinstatements, thus, establish a sufficiently strong memory in non-HPC systems to no longer require the HPC for expression, meaning that it has become HPC independent. This thesis aimed to determine the structures comprising the non-HPC system supporting reinstated context fear memory. The contribution of the perirhinal cortex (PRH) and the anterior cingulate cortex (ACC) were examined because of their established role in context memory. Initially, it was demonstrated that HPC damage indeed causes retrograde amnesia for single session, but not reinstated, contextual fear conditioning. Then, it was demonstrated that combined HPC and PRH damage causes retrograde amnesia for reinstated contextual fear conditioning, whereas combined HPC and ACC damage had lesser effects. Therefore, the PRH is a key structure within the non-HPC memory system for reinstated context fear memory. Author Keywords: anterior cingulate cortex, contextual fear conditioning, hippocampus, memory, perirhinal cortex, retrograde amnesia
Marital Satisfaction Throughout the Journey of Weight-Loss Surgery
A mixed-methods’ approach was designed to explore the marital impacts following weight-loss surgery (WLS). In Phase 1, ten individual interviews with spouses of five couples were conducted; two of the couples had the wives preparing for WLS, two of the couples consisted of wives who had WLS, and one couple had both received the surgery. Interviews were transcribed and analyzed using a combination of interpretive phenomenological and grounded theory techniques. Findings demonstrated that WLS does have impacts on marriage regardless of where couples are in their journey. All couples discussed food as a possible source of conflict in their relationship. Interviews also reveled that self-esteem is a major factor contributing to their relationship and support is necessary throughout. In Phase 2 an online survey was developed to quantitatively explore the important constructs deemed important from the participants in Phase 1. Relationships between relationship satisfaction, sexual conflict, self-esteem, depression and body image were examined in 54 participants. Results demonstrate that higher levels of support and self-esteem and lower sexual conflict relate to a more satisfactory relationship in individuals post- WLS. Author Keywords: marital satsifaction, mixed-methods, qualitative, relationship satisfaction, weight-loss, Weight-loss surgery
Fathering Experience of the Transition Into Parenthood
Men who become fathers undergo a transitional period during which they adjust to their new role as the caregiver of a child, a time that is usually viewed as a major life transition (Lamb, 2010). Much of the published literature focuses on fathers with identified issues (e.g., divorced fathers); therefore, there is a need for research that looks at the experiences of more typical fathers in the current Canadian context. To understand how fathers experience this transition, a series of focus groups were conducted with first-time fathers across the Peel Region of Ontario, Canada. Analysis of the focus group transcripts using an interpretative phenomenology framework identified four overarching metathemes: intrapersonal experiences, extrapersonal experiences, father’s role, and supports. Practical implications, theoretical implications, and limitations are discussed. Author Keywords: Fathering, Fathering Experience, First-Time Fathers, Transition Into Parenthood
“Just Say Yes” - Sexual Consent and Boundary Setting On-and Offlinle
The present study examined the understanding and behaviours relating to sexual consent on, and offline among men who have sex with men (MSM) and heterosexual men internationally using a convergent parallel mixed-methods approach. Men of both sexual orientation groups presented challenges with negotiating sexual consent, and this was especially true if they scored higher on aggressive traits or had previously experienced childhood abuse or an unwanted penetrative sexual act in adulthood. However, from the results as a whole, MSM reported struggle more with regards to consent negotiation for a variety of reasons (e.g. sexual scripts, power dynamics, additional sexual settings, sex-role positioning). Limitations and future directions are discussed. Author Keywords: heterosexual men, men who have sex with men, sexual assault, sexual consent, technology
Tool-use and near-tool effects
After active tool-use visual stimuli near a tool are processed more quickly and accurately than those farther away from a tool. Can these near-tool effects be modulated by training demands? To investigate this we asked the participants to complete a tool training task followed by a cross-modal interference task. During the training task the participants performed quick and accurate pointing movements to reach a strict or moderate criterion. The results indicated that the strict group made faster movements than the moderate group. During the cross-modal interference task visual distractors were presented along handheld tools in conjunction with vibrotactile stimuli on the hand. No significant compatibility effects were found for visual distractors near the hand or tool tip, and no consistent group differences were found. Our findings demonstrate the importance of using a novel tool during training, and that virtual stimuli may not be effective to elicit near-tool effects. Author Keywords: bimodal neurons, cross-modal interference, near-tool effects, tool training, training demands
Investigating Ecological Niche Differentiation Among Wild Candids Experiencing Hybridization in Eastern North America
Currently there are large areas of the North American landscape that are occupied by Canis spp. hybrids of several varieties, leading to the logical question as to the genetic structure and ecological function of Canis populations across the continent, and to what extent hybrids reflect contemporary landscapes. This study illustrated patterns of niche differentiation between parental canid species and their hybrids using individual high quality genetic profile and species distribution models to support the intermediate phenotype hypothesis. In general, hybrids demonstrated an intermediate habitat suitability compared to its parental species, across most environmental variables used. A similar trend was observed in the niche metric analysis, where we found that hybrids exhibit intermediate niche breadth, with eastern coyotes and eastern wolves exhibiting the broader and narrower niche, respectively. Our results demonstrate that the intermediate phenotype hypothesis is supported even at a large scale and when involving highly mobile large mammal species. Author Keywords: canid, ecological niche modelling, hybridization, intermediate phenotype, microsatellite genotype, niche differentiation
Sexual consent
How one identifies their nonconsensual sexual experiences (NSE) and cognitively integrates the experience into their sexual schemas may affect how individuals perceive and negotiate sexual consent. Previous research has demonstrated that both the method of quantifying NSEs and the labels used to describe NSEs yield different results in psychosexual outcomes associated with NSEs. The current study assessed differences in subjectively and behaviourally quantified NSEs, as well as the role of cognitive and affective appraisals of sexuality and sexual interactions, on sexual consent attitudes. While behaviourally measured NSE history did not significantly influence sexual consent attitudes, the subjective identification of NSEs with various labels did influence attitudes toward sexual consent. Cognitive appraisals of rape and affective appraisals of sexuality also significantly predicted sexual consent attitudes. Implications for future research and NSE prevention are discussed. Keywords: Nonconsensual sexual experiences, sexual consent, quantifying NSEs, affective sexuality, cognitive sexuality Author Keywords: identification, nonconsensual sexual experiences, rape, sexual affectivity, sexual assault, sexual consent
Childhood Precursors of Adult Trait Incompleteness
Previous research has suggested that childhood sensory sensitivity may predict adult obsessive compulsive (OC) behaviours. To date, however, research has not addressed how the separate dimensions – harm avoidance and incompleteness - may influence this relationship or why it exists. The current study used a retrospective design to test a) if sensory sensitivity in childhood predicts trait incompleteness in adulthood, as well as b) if emotion regulation variables mediate this relationship. Questionnaires pertaining to OC dimensions and childhood anxieties were completed independently by 172 undergraduate participants and their primary childhood caregiver. Results showed a linear relationship between sensory sensitivity in childhood and incompleteness in adults. Emotion regulation variables failed to mediate this relationship, although a trend for mediation was present. Additionally, exploratory analysis found perfectionism in childhood to be a predictor of trait incompleteness but not harm avoidance, whereas physical anxieties predicted harm avoidance and not incompleteness. Results are discussed in the context of clinical and theoretical implications. Author Keywords: Distress Tolerance, Harm Avoidance, Incompleteness, Obsessive Compulsive Disorder, Sensory Sensitivity, Symmetry

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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