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.
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.
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.
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.
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.
Theory of Mind (ToM) reflects the ability to reason about mental states in order to understand and predict behavior. Research has identified links between increased pulse pressure, a measure of vascular health, and reduced ToM in older adults. Furthermore, previous findings suggest that cognitive ToM is particularly vulnerable to increased pulse pressure. However, to date, the relationships between other chronic vascular and nonvascular conditions and reduced ToM are unknown. We aimed to investigate the effects of vascular and nonvascular illness burden on cognitive and affective ToM in N = 86 older adults (59 females; 27 males, M = 72 years). While vascular illness burden emerged as a significant predictor of older adults’ ToM, nonvascular illness burden was not significantly associated with ToM. Further, executive functioning and semantic memory mediated the relationship between vascular illness burden and cognitive ToM. Our findings highlight the specific importance of considering vascular health as a risk factor for declines in ToM in later life, beyond pulse pressure. Further elucidation of the associations between health, neurocognition and ToM will be valuable in developing effective interventions for older adults given the high prevalence of vascular illness in later life.
Despite the influence that cognitive dissonance theory has had in psychology over the last sixty years, its neural correlates have only recently been investigated. The current study used electroencephalography (EEG) to explore cognitive dissonance-elicited attitude change in a free-choice paradigm. Event-related potentials (ERPs) time-locked to stimulus onset found greater voltage negativity over centro-parietal scalp during re-evaluation of dissonant choice items relative to consonant choice items, and greater negativity over left lateral anterior scalp during trials containing dissonance-reducing attitude change relative to trials without. Left lateral anterior scalp voltage amplitude was found to be negatively correlated with the magnitude of resulting attitude change. A time-frequency analysis revealed effects for high and low alpha and theta frequencies. These finding are consistent with a model of cognitive dissonance in which cortical projections of ventral striatal activity reflect reward signal changes, and where left prefrontal cortex is recruited for cognitive control and emotional down-regulation.
Multimorbid illness, including substance use, psychiatric illness, viral infection, and traumatic brain injury (TBI), is prevalent in marginally housed persons, but it is unclear how these problems influence everyday and social functioning. We conducted mediation analyses in 210 participants in order to evaluate the effects of substance use, psychiatric illness, viral infection, and traumatic brain injury on predicting 6-month follow-up ratings of functioning, and to examine whether neurocognitive performance significantly mediated the relationship between these health characteristics and ratings of functioning. Neurocognition, alongside positive and negative symptoms, explained 47% of the effect of schizophrenia on functioning and 11% of the effect of TBI on functioning. Additionally, greater heroin use frequency was significantly associated with lower ratings of functioning, but this effect was not mediated by neurocognition. Our findings highlight the role of neurocognition in mediating the relationship between illness and functioning in the marginally housed, and inform treatment targeting toward specific morbidities in populations with complex health issues.
In order to effectively search the visual environment, an observer must continually locate objects of interest amid an abundance of irrelevant and distracting stimuli. These visual distractors can sometimes inadvertently attract attention to their locations, even when an observer is attempting to search for an entirely different object. To deal with visual distractors, it has been well established that the visual system can implement a suppression mechanism to filter out irrelevant stimuli. Within the past decade, event-related potential (ERP) recordings have isolated an attentional component that is thought to reflect this suppressive processing. This ERP component—termed the distractor positivity (PD)—has been used to demonstrate that the sensory processing of irrelevant information can be strongly modulated in line with the visual search goals of an observer. Here, four electrophysiological studies of attention are presented which focus on yielding insight into how the visual system deals with irrelevant information during visual search and seeks to further our understanding of the PD component. Chapter 2 tests the stimulus conditions necessary to elicit the distractor suppression indexed by the PD by examining how differences in the salience of an irrelevant stimuli affect visual search. Chapter 3 explores how individual differences in target and distractor processing are associated with variations in visual working memory (vWM) capacity. Chapter 4 asks how distractor processing is altered during a disruption of attentional control by examining how visual search is affected during the attentional blink (AB). Chapter 5 explores how high levels of trait anxiety alter inhibitory control and the ability to ignore distracting information. In the final chapter, future directions are discussed and a model for attentional processing is proposed.
Despite a long tradition of studying psychometric properties of self-report questionnaires in psychology, the literature identifying specific linguistic features of questionnaire items is sparse. Moreover, it is unclear whether linguistic features affect all individuals similarly, or interact with individual characteristics. The present study offers a novel methodological contribution whereby a variety of linguistic features, based on the domains typically studied by linguists (i.e., morphology, syntax, semantics), are proposed. To demonstrate how these itemmetrics can be used empirically, we analyzed data from the Center for Epidemiological Studies-Depression (CES-D) scale. Additionally, we probed interactions between sex and English fluency and each of the features to examine whether there were differential effects depending on the individual. Our results suggest that certain features may impact responding and interact with individual characteristics. We argue that our findings necessitate a stronger focus on this area of research.