Psychology - Theses, Dissertations, and other Required Graduate Degree Essays

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On quantitative issues pertaining to the detection of epistatic genetic architectures

Author: 
Date created: 
2021-01-25
Abstract: 

Converging empirical evidence portrays epistasis (i.e., gene-gene interaction) as a ubiquitous property of genetic architectures and protagonist in complex trait variability. While researchers employ sophisticated technologies to detect epistasis, the scarcity of robust instances of detection in human populations is striking. To evaluate the empirical issues pertaining to epistatic detection, we analytically characterize the statistical detection problem and elucidate two candidate explanations. The first examines whether population-level manifestations of epistasis arising in nature are small; consequently, for sample-sizes employed in research, the power delivered by detectors may be disadvantageously small. The second considers whether gene-environmental association generates bias in estimates of genotypic values diminishing the power of detection. By simulation study, we adjudicate the merits of both explanations and the power to detect epistasis under four digenic architectures. In agreement with both explanations, our findings implicate small epistatic effect-sizes and gene-environmental association as mechanisms that obscure the detection of epistasis.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Michael Maraun
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

School connectedness & attachment: Predicted and moderated relationships with substance use, depression, and suicidality among teens at-risk

Author: 
Date created: 
2020-12-14
Abstract: 

Research has demonstrated that parent-adolescent attachment security and school connectedness are protective factors that buffer teens from risk for substance use, depression, and suicidality. However, past research has examined these factors independently, and little is known about how secure attachment and school connectedness work in conjunction to reduce adolescent risk. The present study examined the moderating role of school connectedness on the relationship between parent-adolescent attachment security and substance use, depression, and suicidality among at-risk adolescents drawn from a clinical sample (N = 480; 60.5% female; Mage = 14.86). Findings indicated that for both females and males with a secure attachment, school connectedness made a positive impact to reduce symptoms of depression and suicidality, respectively. Similarly, for males with attachment avoidance, school connectedness weakened the impact of attachment avoidance on suicidality. However, for females with attachment anxiety, school connectedness was unable to reduce symptoms of depression.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Marlene Moretti
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

Incident traumatic brain injury in precariously housed persons

Author: 
Date created: 
2020-11-04
Abstract: 

Persons living in precarious housing face numerous mental and physical health risks, including disproportionally higher incidence of traumatic brain injury (TBI) compared with the general population. A number of challenges hamper the existent literature on incident TBI in this population, potentially attenuating estimates of TBI occurrence. In precariously housed persons, this study (1) captured TBI events in a prospective design that included participant education regarding injury sequelae and the use of a comprehensive and validated screening tool deployed repeatedly and proximate (i.e., monthly) to incident TBI, (2) characterized the types of TBI events that occurred through detailed assessment of injury details (i.e., count, severity, mechanism, acute intoxication), with test-retest reliability analyses on self-reported injury characteristics, and (3) identified specific risk factors for incident TBI, amongst broad predictor categories (i.e., substance dependence, psychiatric illness, prior brain injury, psychological functioning), through detailed pre-injury assessment, in order to inform targeted assessment and prevention strategies. Three hundred and twenty six participants were recruited from single-room occupancy hotels and screened monthly for incident TBI. Observed and estimated rates of TBI were obtained, and logistic and poisson regression identified pre-injury risk factors for TBI occurrence, severity, and count. Across TBI definitions and approaches to missing data, incidence proportion ranged from 18.7 to 50.7 percent, event proportion ranged from 27.9 to 91.1 percent, incidence rate ranged from 30,086 to 50,674 per 100,000 person-years, and event rate ranged from 44,882 to 91,104 per 100,000 person-years. Education, role functioning, schizophrenia spectrum disorder, opioid dependence, lifetime number of TBI, and lifetime history of TBI were significant predictors of TBI occurrence. This study makes four important contributions: (1) screening for brain injury at repeated proximal assessments (i.e., monthly) obtains a considerably higher self-reported rate of TBI in precariously housed persons, (2) this multimorbid population suffers from remarkably high rates of self-reported brain injury, and (3) several key and specific risk factors for TBI occurrence and (4) TBI severity were identified. Harm reduction strategies targeting those most vulnerable are imperative to improve functioning and prevent further injury and associated consequences.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Allen Thornton
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.

The role of psychological distress and sport participation on help-seeking among university student athletes

Author: 
Date created: 
2020-11-23
Abstract: 

Student athletes are considered less likely to seek help than non-athlete students despite comparable rates of mental health difficulties. However, recent findings suggest certain variables may influence these differences. The present study used a secondary analysis of a national sample of university students to explore the role of psychological distress on help-seeking among student athletes and non-athlete students. Results indicate student athletes are less likely to consider help-seeking than non-athlete students. However, the association of psychological distress and help-seeking intention did not differ across level of sport participation. Unique predictors among student athletes indicate that athletes who are in fourth year and above, had previously sought help, or were experiencing greater psychological well-being demonstrated increased help-seeking intention. Psychological distress was associated with reduced intention. This study expands upon the growing body of student athlete help-seeking research and reinforces the importance of investigating strategies to better support this unique population.

Document type: 
Thesis
File(s): 
Supervisor(s): 
David Cox
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

The relation between linguistic and manual asymmetries in bilinguals and monolinguals

Author: 
Date created: 
2020-09-22
Abstract: 

Humans are unique in their ability for language and a strong population-wide right-hand preference for object manipulation. A number of researchers (e.g., Arbib, 2005; Crow, 2002) suggest that an association between language asymmetry and handedness was crucial for human evolution and development. However, developmental studies on language and handedness association demonstrate mixed results. Importantly, only a small number of developmental studies addressed handedness-language relations in adults. Moreover, the majority of studies on handedness and language relations rely on homogeneous samples of right-handed monolingual English speakers. To this day it is not known whether the results of such studies can be extrapolated to bilingual people, and whether results obtained from studies with children can be extrapolated to adults. The current study is the first of its kind systematically examining handedness and language in a sample of over 1,800 participants with diverse language background (over 50 different languages). The study examined handedness and language asymmetry in monolinguals, early bilinguals (acquiring a second language before age 6) and late bilinguals (acquiring a second language after age 6). Additional parameters such as motor asymmetry (a preference for right footedness) and gender were also examined for potential effects on asymmetry formation in all participants. Finally, a subsample of monolingual and bilingual participants was examined on asymmetry of a gesture and object manipulation. Study results suggest that contrary to previous claims of language asymmetry and handedness association, they are not strongly related in adults. Language asymmetry and the age of the second language acquisition predicted only a small portion of handedness score. Footedness and gender were stronger predictors of handedness. Females exhibited stronger asymmetry than males; more right-footed participants tended to be more right-handed. Contrary to studies with children, current study adult participants were more strongly lateralised for object manipulation than for gesture. In conclusion, the current study suggests that handedness and language relations are dynamic in development; that their relations are not as robust as was previously suggested; and finally, that the research field of handedness-language relations would benefit from diversifying study samples.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Timothy Racine
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.

Examining sense of self and identity in schizophrenia: A modified grounded theory study

Date created: 
2020-09-25
Abstract: 

Alterations or losses to one’s sense of self and identity are identified in the literature as being an important aspect of the lived experience of schizophrenia. Research further implicates regaining a sense of self and identity as playing an important role in recovery and wellbeing in schizophrenia. Despite this, a comprehensive understanding of the specific component processes involved in changes to sense of self and identity in schizophrenia has not been clearly elucidated. The current study aimed to examine and characterize the major component processes involved in alterations to sense of self and identity in schizophrenia. Using qualitative methodology, eight adult participants (age range = 31 to 55 years old, M = 45; four cisgender women, one transgender man, three cisgender men) with schizophrenia or schizoaffective disorder were individually interviewed. The interview topics included: personal understanding of the nature of schizophrenia, self-perception prior to schizophrenia, changes in self-perception through experiencing schizophrenia, coping strategies, views on current sense of self and identity, and knowledge gained about oneself through experiencing schizophrenia. Interview transcripts with analyzed using a modified Grounded Theory methodology. Five participants completed member checking procedures to verify the interpretation of the data. The data supported the conceptualization of three over-arching categories reflecting significant component processes of change to sense of self and identity in schizophrenia: (1) disruptions and interruptions to sense of self and identity, (2) finding stability, and (3) multiple pathways to (re)building a sense of self and identity through finding meaning and purpose. While the individual experience may be idiosyncratic, the findings suggest that commonalities exist in the nature of changes to sense of self and identity. The findings also indicate how individuals with schizophrenia may benefit from interventions that focus on self and identity.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Robert Ley
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.

Nonsuicidal self-injury expectations and psychopathology over time: Linear and nonlinear multilevel modelling approaches

Author: 
Date created: 
2020-08-20
Abstract: 

Nonsuicidal self-injury (NSSI), the deliberate self-infliction of tissue damage, is a serious behaviour with a host of negative consequences that has a considerable impact on the health system. People engage in NSSI for a variety of reasons and often expect desirable outcomes from NSSI (e.g., relieving emotions, communicating to or influencing others). Understanding the link between these expectations and various symptoms of psychopathology will help to refine theoretical models of NSSI and inform treatment. Female participants (N = 197) with a recent history of NSSI completed online measures of self-injury, psychopathology and psychological distress (including suicidality and depressive symptoms), and social support at 3-month time points for 24 months. Multilevel regression analyses of these time series data indicated that suicidality and depressive symptoms were positively associated with greater endorsement of intrapersonal NSSI expectations concurrently, and that depression positively predicted intrapersonal NSSI expectations at the following 3-month time point. Depressive symptoms were associated with interpersonal NSSI expectations concurrently but not prospectively. Overall, these findings further validate models of NSSI that distinguish between intrapersonal and interpersonal expectations within a longitudinal framework and suggests applications relevant to person-centred case conceptualizations of NSSI and NSSI treatment.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Alexander Chapman
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.

Relationships between parent affect regulation, mindful parenting, attachment, and internalizing and externalizing symptoms in a clinical adolescent sample

Author: 
Date created: 
2020-10-20
Abstract: 

Adolescents are vulnerable to the onset of psychological disorders, yet research on parenting factors that promote adolescent mental health is sparse. Attachment security is a strong predictor of mental health outcomes so identifying parenting factors that support attachment security among adolescents may offer insight into modifiable factors that can be targeted in intervention. In a clinical sample of 785 families, this study examined the relationships between mindful parenting, parent affect regulation, adolescent-parent attachment anxiety and avoidance, and adolescent internalizing and externalizing symptoms. Analyses modelled the pathways from mindful parenting and parent affect regulation to attachment anxiety and avoidance, and, in turn, internalizing and externalizing symptoms. Mindful parenting and parent affect regulation were differentially related to attachment anxiety and avoidance, and indirectly predicted internalizing and externalizing symptoms through attachment anxiety and avoidance. These factors may be useful clinical targets for interventions aiming to promote attachment security and mental health in adolescents.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Marlene Moretti
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

An evaluation of the reliability and quality of expert and novice forensic case formulations

Author: 
Date created: 
2020-08-13
Abstract: 

Forensic case formulation is an under-studied and growing area within the violence risk assessment literature. The current study aimed to address gaps in the literature by examining the interrater reliability (IRR) and quality of forensic case formulations by comparing Expert and Novice raters. N = 50 intimate partner violence offender files were accessed. Four raters (n = 2 Experts, n = 2 Novices) rated each file using all steps of Spousal Assault Risk Assessment Guide-Version 3 (SARA-V3; Kropp & Hart, 2015). Cases were formulated using a Decision Theory approach in which motivating, disinhibiting, and destabilizing mechanisms were identified. The distribution of ratings for these mechanisms was presented. IRR was examined using a novel coefficient, Gwet’s AC. Raters also completed narrative case formulations. Then a Within Case and Across Case paired case design involving n = 143 narrative formulation pairs was conducted with three new raters. The similarity of paired formulations was evaluated. Raters also assessed the quality of formulations using the Case Formulation Quality Checklist-Revised (CFQC-R; McMurran & Bruford, 2016). For most formulation mechanisms, distribution of Presence ratings was skewed. Overall, across Experts and Novices, the IRR of formulation mechanisms ranged from poor to almost perfect (AC2 = .10. - .98), with most coefficients falling between the moderate and almost perfect ranges. The similarity of formulations was established; Within Case paired formulations were judged as more similar than Across Case paired formulations. Finally, formulations were high in quality; Experts produced higher quality formulations than Novices.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Stephen D. Hart
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.

Negative affect and self agency’s association with medication adherence in adult organ transplant recipients: A meta-analytic study

Author: 
Date created: 
2020-07-09
Abstract: 

Objective: In organ transplant, prevalence estimates of negative affect (e.g., depressive symptoms) are higher than in the general population and self-agency is required for successful medication regimen self-management. Nonetheless, the roles of these psychological factors for immunosuppressant adherence in the organ transplant population remain unclear. Methods: Meta-analytic techniques were used to determine the associations between negative affect and self-agency with immunosuppressant adherence and to identify theoretically derived and methodological moderators of these associational effect sizes (ES). Results: Across 50 studies and 46,106 adult organ recipients, the findings demonstrate that there is a small negative association between negative affect and adherence [mean weighted effect size: r= -.14, p= .00; 95% CI= -.175, -.096] and a small positive association between self-agency and adherence [ES: r= .17, p= .00; 95% CI= .094, .251]. Studies conducted outside of Europe and North America, assessing illness-specific negative affect and utilizing questionnaire adherence measures, and studies of better quality were associated with a larger effect size for the association between negative affect and adherence, and together they explained 54% of the heterogeneity in the effect sizes. For the association between self-agency and adherence, a higher percentage of females and medication-specific self-agency were associated with a larger effect size, explaining 34% of the heterogeneity in the effect sizes. Conclusions: By elucidating overlooked trends in the existing literature for the associations between negative affect and self-agency with immunosuppressant adherence, the current meta-analyses clarify previously contradicting findings in organ transplant and demonstrate that higher negative affect and lower self-agency are each associated with poorer adherence to immunosuppressants in organ transplant. The findings also shed light on six factors contributing to the existing variability in effects and highlight the importance of careful consideration of study methodology in studies of adherence to immunosuppressants post organ transplant.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Wendy Thornton
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) Ph.D.