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

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Perceptual Salience and Its Consequences on Attentional Object Selection

Date created: 
2017-03-31
Abstract: 

This thesis investigated the effects of salience on visual object selection, and focused on whether salience impacts the visual system’s ability to process multiple items at the same time (parallel selection) or one-at-a-time (serial selection). Chapter 2 consists of two experiments that used an ERP component, the N2pc, to track the deployment of attention in a visual search task with highly dissimilar distractors. Although the time to find the target increased with the number of distractors, observers were able to select the target at the same time, regardless of the size of the search display. This suggests that task relevance can make otherwise non-salient items “pop out” at the level of attentional selection. Chapter 3 comprises a single experiment in which attentional selection was measured overtly, using eye tracking, as observers inspected and compared two singletons of differing salience. Discreet eye movements were made from one singleton to the other and the order of inspection was strongly biased by target salience, with the initial saccade being made to the more salient singleton on the vast majority of trials. This suggests that, in the absence of top-down control, the order of attentional selection is dictated by salience. Finally, Chapter 4 consists of three variants of the same two-singleton search task used in Chapter 3. The first experiment replicated Chapter 3 but with attentional selection tracked covertly via the N2pc. In the next two experiments, task parameters were manipulated to encourage slower shifts of attention from one singleton to the other and to encourage the initial inspection of the less salient singleton. Attentional object selection was purely serial in some cases and partially parallel in others. The biasing effect of salience could also be subverted, such that the less salient item was selected first, however that item was not selected as rapidly as the more salient item. Chapter 4 thus reveals that (i) the earliest time at which an item becomes available for attentional selection depends on its relative salience, and (ii) the speed of attentional redeployment varies with the nature of the response required.

Document type: 
Thesis
File(s): 
Senior supervisor: 
John McDonald
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Dissertation) Ph.D.

Endocrine response to social rejection: The effect of testosterone and cortisol on pain sensitivity

Date created: 
2017-03-30
Abstract: 

An expanding body of literature suggests that common neural underpinnings governing physical and social pain are evolved adaptations that punish social disengagement by using pain as a signalling mechanism for social rejection. Such a mechanism is necessary in the face of fitness benefits afforded by group living from which a ubiquitous need to belong has grown. Salivary testosterone and cortisol were examined in the context of fluctuating pain sensitivity in response to a social evaluation with a confederate. It was expected that a greater evolutionary prescribed tendency to seek interpersonal support would result in physiological responses to rejection in females leading to reductions in pain sensitivity. While non-significance was found for cortisol, results implicate testosterone as an important factor in altering sensitivity after social interactions in men. This relationship between testosterone and pain may be a function of dominance and increased status seeking resulting from acceptance in a social interaction.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Neil Watson
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

Distinguishing between primary and secondary callous-unemotional features in youth: The role of emotion regulation

Date created: 
2017-02-27
Abstract: 

Background: Research on youth with callous-unemotional features (CU features; e.g., lack of empathy) has historically categorized these behaviors as biologically-driven and homogeneous across development. However, an early model proposed that two subtypes of CU features exist with different etiological factors. The first, or ‘primary’ group, has a genetically based deficit in emotion processing, resulting in a diminished sensitivity to others’ emotional cues. The ‘secondary’ CU group is conceptualized as an adaptation to environmental factors such as maltreatment and are characterized by an affective deficit produced by these powerful environmental factors. Secondary youth are typically classified or grouped based on the presence of co-occurring anxiety symptoms. Understanding the presentation of regulation strategies among CU variants may give us further insight into the different pathways to their development. In addition, due to the high number of samples that have relied on justice-involved males, there is a paucity of research on gender differences across the variants. Purpose: The aim of the current study was to evaluate whether distinct groups of youth may be identified in a clinical sample by using measures of affect dysregulation and suppression, anxiety symptoms and experience of maltreatment. It was also to examine whether these distinct groups were consistent across males and females. Method: Participants (N = 418; 56.7% female) ranged in age from 12 to 19 (M = 15.04, SD = 1.85) and were drawn from the baseline of a large clinical sample. Results: A Latent Profile Analysis (LPA) was conducted using five indicators including affect regulation, suppression, anxiety, CU features, and maltreatment. The best fitting model, a 4-class solution, had a significant Lo-Mendell-Rubin (p= .003), an acceptable entropy score (.78), and classification probabilities that suggested accuracy and good separation. The four groups to emerge included a low, anxious, primary CU, and secondary CU group. Gendered LPAs found a 4-class model fit for both males and females (entropy= .866). Gender did not moderate other outcomes of interest. Discussion: This study extends previous literature by including the underlying process of dysregulated affect to the model in identifying primary and secondary subgroups and examining gender. Clinical implications are discussed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Marlene Moretti
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Dissertation) Ph.D.

The impact of viral infections on neurocognitive functioning in the context of multiple risk factors: Associations with health care utilization

Date created: 
2017-01-30
Abstract: 

Marginally housed persons experience several risk factors for neurocognitive impairment, including viral infections, psychiatric illness, and substance use. Although interventions exist, marginalized persons often obtain inadequate health services, based upon personal and structural barriers. In study one, we employed structural equation modeling to assess determinants of neurocognition (i.e., viral infections, psychiatric symptoms), predicting that any impairment would impede healthcare access. Our findings revealed that greater exposure to viral infections and more severe psychiatric symptoms were similarly associated with poorer neurocognition. Additionally, more frequent opioid use/less frequent alcohol and marijuana use was associated with better neurocognition. Only viral infections directly predicted healthcare use, an association that was positive despite the negative impact viral infections held with neurocognition. In study two, we assessed whether spontaneous clearance of Hepatitis C (HCV) is associated with reversal of neurocognitive impairments by comparing three groups: cleared-HCV, active-HCV, and no exposure to HCV. Our findings did not confirm improved neurocognition with HCV clearance, nor did we find any differences between groups exposed to HCV versus those never exposed to the virus after controlling for the effects of Hepatitis B (HBV). Nevertheless, our findings revealed that HCV conveys adverse health in marginalized persons (i.e., HCV exposure is associated with increased rates of HIV, liver dysfunction, etc.). Overall, these findings confirm the detrimental impact of viral infections on neurocognition in marginalized persons. Moreover, although neurocognition did not emerge as a personal barrier to accessing care in marginalized settings, structural level barriers may be operating. Specifically, our results point to a system where health care is selectively utilized and may not be targeted towards all persons, such as those experiencing elevated psychiatric symptoms.

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

An evaluation of a program supporting Indigenous youth through their FASD assessment

Author: 
Date created: 
2017-01-16
Abstract: 

This dissertation was a program evaluation of a three-year program focusing on the intersection of health, justice and child welfare in relation to FASD where holistic, culturally-informed support services are provided to justice-involved Indigenous youth before, during, and after FASD assessments. Fetal alcohol spectrum disorder (FASD) is a diagnostic term used to describe the resulting neurodevelopmental impacts of prenatal alcohol exposure. Not only is FASD a health concern, but FASD is also a concern within justice and child welfare. There are several areas where an individual living with FASD may experience difficulties navigating the justice system and advocating for themselves. Children living with FASD are also more likely to be wards of child welfare agencies. At the heart of this Program, the focus is on exploring, revitalizing, and nurturing cultural connections and Indigenous identity. The scope of this evaluation focused on a formative and process evaluation which aimed to garner information for program improvement. A total of six Program staff and management and three Program advisory committee members participated in evaluation interviews developed by the evaluator, and 65 Program stakeholders participated in a program needs assessment survey. Evaluation data collection tools were developed in a participatory manner with the Program manager and staff. Qualitative data were hand-coded using thematic analyses. Findings from the evaluation showed the strengths of Indigenous youth living with FASD are plenty, yet also underscored the many challenges they face in accessing services and being supported. Several needs emerged from the evaluation, including needs around brain-based services, public awareness and education, culturally-informed services and professionals, holistic support, and access and exposure to culture and identity. Evaluation findings showed that the Program is reaching the right youth and the holistic design was perceived to be effective. While the Program rolled out differently than designed, adaptations were necessary to address the needs of those being served. Findings also highlighted that the Program is contributing to community level changes in stigma, and increases in cultural connections and identity among youth. Findings from this evaluation are informative for the Program in moving forward as several recommendations for program improvement were developed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ronald Roesch
Department: 
Arts & Social Sciences: Psychology
Thesis type: 
(Dissertation) Ph.D.

Structural brain markers are differentially associated with neurocognitive profiles in socially marginalized people with multimorbid illness

Date created: 
2016-11-21
Abstract: 

Homeless and marginally housed individuals constitute a socially impoverished population characterized by high rates of multimorbid illness that includes polysubstance use, viral infection, and psychiatric illness. Their extensive exposure to risk factors is associated with numerous poor outcomes, yet little is known about structural brain integrity and its association with neurocognition in this population. In Study 1, we conducted a cluster analysis to re-construct three previously derived subgroups with distinct neurocognitive profiles in a large sample of socially marginalized persons (N = 299). Cluster 1 (n = 87) was characterized as highest functioning overall, whereas Cluster 3 (n = 103) was the lowest functioning neurocognitively, with a relative strength in decision-making. Cluster 2 (n = 109) fell intermediate to the other subgroups, with a relative weakness in decision-making. Next, we examined the association between complementary fronto-temporal cortical brain measures (gyrification, cortical thickness) and neurocognitive profiles using multinomial logistic regression. Chi-square tests and ANOVAs differentiated subgroups on proxy measures of neurodevelopment and acquired brain insult/risk exposure. We found that greater frontal and temporal gyrification and more proxies of aberrant neurodevelopment were associated with Cluster 3 (lowest functioning subgroup). Further, age moderated the association between orbitofrontal cortical thickness and neurocognition, with positive associations in older adults, and negative associations in younger adults. Finally, greater acquired brain insult/risk exposure was associated with the cluster characterized by selective decision-making impairment (Cluster 2), and the higher functioning cluster (Cluster 1). In Study 2, we examined the association between white matter integrity and neurocognitive profiles using multinomial logistic regression and Tract-based Spatial Statistics. We found significantly lower fractional anisotropy (FA), with corresponding increased axial and radial diffusivity (AD, RD) in widespread and bilateral brain regions of Cluster 3. Differences in RD were more prominent compared to AD. Altogether, our findings highlight the unique pathways to neurocognitive impairment in a heterogeneous population and help to clarify the vulnerabilities confronted by different subgroups.

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

Developmental antecedents of sadness and anger rumination: Examining the roles of attachment and affect regulation

Author: 
Date created: 
2016-12-01
Abstract: 

The role of rumination in the development and maintenance of psychopathology has been well established. Far less is known however, about possible precursors to this repetitive thinking style. The current study examined two potential developmental antecedents of rumination: insecure attachment and affect regulation. Reports of attachment anxiety and avoidance with maternal figures were examined as predictors of both sadness and anger rumination in a sample of high-risk youth. Affect dysregulation and suppression were also assessed as potential mediators of these associations. Participants completed questionnaires at three time points within a five-year period, with the current study examining associations concurrently at Time 1 and prospectively across Time 2 and 3. Gender differences in these relationships were also assessed. Participants at Time 1 were 159 adolescents (84 males, 75 females) between the ages of 12 and 18 years (M = 15.41, SD = 1.52). Concurrent and prospective associations were tested within a path analysis framework. With respect to concurrent relationships at Time 1, statistically significant associations were found between affect dysregulation and anger rumination for females and males. The association between anger rumination and attachment anxiety was small to moderate, and not statistically significant. Associations between sadness rumination and both attachment avoidance and affect suppression were also not statistically significant for either gender. When examining relationships across time, attachment anxiety significantly predicted increased anger rumination only in females. Affect dysregulation was significantly associated with higher levels of anger rumination for both females and males. Despite this, affect dysregulation did not mediate the association between attachment anxiety and anger rumination. With respect to sadness rumination, attachment avoidance was found to be a significant predictor in females. Implications of these findings for preventative and intervention efforts are discussed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Marlene Moretti
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Dissertation) Ph.D.

“The things we all celebrate”: Aboriginal parents’ conceptualizations of a broad Aboriginal identity in the context of the Aboriginal Focus School in Vancouver

Date created: 
2016-12-15
Abstract: 

This thesis provides a thematic analysis of how urban Aboriginal parents (N=31) discussing the Aboriginal Focus School in Vancouver conceptualize the broad Aboriginal category as a meaningful identity. Participants conceptualized the broad Aboriginal category as a reflection of the lived experience of urban Aboriginal peoples, as a group with cultural commonalities including shared practices, norms and values, as a collection of diverse Aboriginal cultural groups in which subgroup diversity contributes to the value of the broad Aboriginal identity, and as a basis for solidarity and resilience in response to mistreatment from outgroups. Results also suggest the broad Aboriginal category is most likely to be accepted when it is perceived to be constructed by Aboriginal people themselves. These findings are situated within the Social Identity Theory approach (Reicher, Spears & Haslam, 2010) and add nuance to research on multicultural identities, intragroup relations and the political implications of social category construction.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Michael Schmitt
Department: 
Arts & Social Sciences: Psychology
Thesis type: 
(Thesis) M.A.

The role of lane position in right-of-way violation collisions involving motorcycles

Author: 
Date created: 
2016-12-02
Abstract: 

Low motorcycle conspicuity is believed by many researchers, drivers, and motorcyclists to be causally involved in motorcycle collisions that involve another driver. Substantial improvements in motorcycle conspicuity have been made over the last four decades, but in spite of this, motorcycle collisions involving other vehicles are on the rise, specifically the type of collision where another driver violates the motorcyclist’s right-of-way because they “did not see them”. Because the hypothesis that motorcycles lack conspicuity in traffic is so intuitively appealing and so pervasive, it has never been tested. This work provides an argument against the notion that right-of-way-violation collisions are due to poor motorcycle detection resulting from their low conspicuity and proposes an alternate hypothesis: These collisions seem related to failures in motion-perception which are partially caused by the motorcycle’s approach path in a left-of-lane position which, ironically, is partly intended to increase the motorcycle’s conspicuity.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Thomas Spalek
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.

The Structured Assessment of Protective Factors for Violence Risk – Youth Version (SAPROF-YV): The Association Between Protective Factors and Aggression in Adolescents

Author: 
Date created: 
2016-12-07
Abstract: 

The Structured Assessment of Protective Factors for Violence Risk – Youth Version (SAPROF-YV; de Vries Robbé et al., 2015) is a new measure of protective factors that is used with a risk-focused tool, such as the Structured Assessment of Violence Risk in Youth (SAVRY; Borum et al., 2006), to provide a more balanced assessment of risk. The present study investigated the relationship between the SAPROF-YV and aggression in a sample of 69 adolescents. Using a retrospective study design, files were reviewed at an inpatient treatment facility and a probation office. Results indicated that the SAPROF-YV demonstrated good convergent and discriminant validity with the SAVRY. The SAPROF-YV was predictive of the absence of verbal and physical aggression; however, it did not add incrementally to SAVRY Risk factors. Finally, some evidence suggested the SAPROF-YV was more predictive for higher risk adolescents than lower risk adolescents. Implications for research and clinical applications are discussed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jodi Viljoen
Department: 
Arts & Social Sciences: Department of Psychology
Thesis type: 
(Thesis) M.A.