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This faculty member is currently not looking for graduate students or Postdoctoral Fellows. Please do not contact the faculty member with any such requests.
Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
Despite substantial advances in research on hoarding disorder over the past decade, the mechanisms driving hoarding behaviour remain poorly understood. It is well established that people who hoard feel justified in keeping objects that most individuals would consider worthless. However, there has been little empirical investigation of the decision-making process that provides people who hoard with justification to save objects that most people would discard. The current research proposed that people who hoard are routinely biased towards saving because they engage in a decision-making process that excessively prioritizes factors that favour keeping possessions (i.e., potential future utility) and neglects factors that would normatively encourage discarding (i.e., infrequent past usage, lack of household space, object dysfunction). This model builds on previous research suggesting that people who hoard are abnormally concerned about needing possessions in the future, and Frost and Hartl’s (1996) theoretical proposition that people who hoard have a higher threshold for discarding useless objects.To test this hypothesized model, the current research developed three novel decision- making tasks about household possessions: the Information Seeking Task, the Vignette- Based Task, and the Dysfunction Tolerance Scale. Once validated, these tasks were completed by a community sample (N = 174) of individuals with varying levels of hoarding symptoms. Analyses examined the relationship between task performance and hoarding as both a categorical (i.e., hoarding disorder (n = 53) vs. healthy control (n = 76)) and dimensional construct (i.e., severity of self-reported hoarding symptoms).As predicted, when making discarding decisions, hoarding participants were less responsive to information that would decrease the perceived value of objects, such asiinfrequent use, poor condition, and lack of household space. The hoarding group also displayed a greater preference than the healthy control group for considering information that would promote saving (i.e., potential future uses of objects) when making discarding decisions. Although the results supported a consistent view of individual differences in discarding decision-making in hoarding, several of the effect sizes were small. The current findings provide several promising directions for future research. Moreover, the current work offers practical suggestions for enhancing current hoarding interventions that target maladaptive decision-making about possessions.
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Hoarding disorder is a complex form of psychopathology that is characterized by excessive accumulation of items and extreme difficulty parting with possessions. It affects 2% to 6% of the population and is associated with significant distress, impairment, and cost to affected individuals, their family and friends, and society. Hoarding disorder is a new diagnosis. Theoretical models and treatment protocols are, therefore, emergent.Valuing of items is notably abnormal in hoarding disorder and the theory of value from economics provides a suitable framework for examining this phenomenon. Individuals with hoarding disorder accumulate a much larger number of items than do most people, and many of those items are objectively worthless. Revealed preference suggests that excessive accumulation of items can be explained by overvaluation of items relative to other goods. Also, in hoarding, often multiple units of the same item are kept when one would suffice. This could be explained by attenuated diminishing marginal value. Finally, hoarding is associated with extreme difficulty parting with possessions, which is consistent with an enhanced endowment effect. The current research assembles the phenomena of abnormal valuing into a coherent theoretical model and conducts initial empirical investigations to test predictions from the theory.Valuing of everyday household items, diminishing marginal value, and the endowment effect were examined among 128 participants: 43 with hoarding disorder, 46 with subclinical levels of hoarding symptoms, and 36 healthy controls. Participants attended one lab session and completed a clinical interview, computer-based questionnaires, and three valuing tasks. Data were analysed using ANOVA and regression models.Hoarding symptoms and cognitions were both positive predictors of the number of no-cost and sentimental items that participants attributed with some value. Hoarding was a unique predictor of attributing value to sentimental items, whereas, hoarding was confounded with other aspects of psychopathology in predicting valuing of no-cost items.These results suggest that individuals with hoarding disorder are particularly adept at finding value in items that others would consider to be worthless. This could be an important focus for treatment. Avenues for future research are suggested in the areas of hoarding disorder, behavioural economics, and item ownership.
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Concern about the spread of infectious agents and associated washing and avoidance behaviour vary widely across individuals. Extremes on either end of the spectrum can have negative consequences: overconcern can lead to undue distress and excessive cautionary behaviour, and underconcern can lead to the contraction and spread of disease. The purpose of this series of four studies was to examine variables that contribute to individual differences in judgments of contaminant spread. Specifically, I examined whether threat influenced judgments of spread.Studies 1 and 2 were conducted with a general (unselected) sample of participants recruited from a university campus (N = 75 and N = 77 respectively), while Studies 3 and 4 extended the research to two specific populations of interest (49 nursing students in Study 3 and 21 participants with contamination-related OCD in Study 4). Participants were randomly assigned to judge the spread of either a: threatening contaminant (disease-causing bacteria), non-threatening contaminant (harmless bacteria) or non-contaminant (vegetable juice in Study 1, yogurt containing probiotic bacteria in Studies 2, 3 and 4). To ensure participants’ safety, these substances were not actually present—rather participants were led to believe that one of these substances was placed on a cutting board and then spread to a series of objects.Findings varied depending on the specific facet of spread examined and the population under study. Among the general university sample and participants with OCD, identification as a contaminant increased judgments of physical spread, but threat did not. Among nursing students, there was a trend for threat to increase judgments of physical spread. With regard to danger along the chain of contagion, threat increased danger ratings for the general university sample and nursing students, but not for participants with OCD. Rather, the OCD group viewed danger as elevated along the chain of contagion for both contaminants. Threat also increased avoidance for the general university sample and nursing students, but not the OCD group. Participants with OCD tended to engage in high levels of avoidance regardless of which condition they were in. Discussion focuses on the studies’ implications for understanding fear of contamination and hygiene behaviour.
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Nicotine cravings are important predictors of smoking cessation difficulty and relapse. Metacognitive models suggest that the ways people think about and respond to cravings may affect how severe cravings become. Specifically, appraising cravings to mean something awful about oneself or one’s quit attempt (i.e., as meaning one is weak-willed, destined to fail, or out of control) is predicted to increase distress. Negative affect is then theorized to trigger further craving and motivate unhelpful coping responses such as thought suppression and rumination. The present study examined evidence for this metacognitive model using an experimental paradigm. One hundred and seventy-six adult smokers participated in two lab sessions either during or preceding a cessation attempt; during the first session, participants received metacognitive, control or no psychoeducation. Dependent variables were assessed using ecological momentary assessment and questionnaires four days later. Metacognitive models predict that overly negative beliefs increase cravings and withdrawal-related distress. Consistent with this hypothesis, metacognitive beliefs correlated with increased distress and withdrawal symptoms among both continuing smokers and active quitters. Providing psychoeducation challenging maladaptive beliefs about cravings did not causally impact craving or smoking four days later, but psychoeducation was associated with differential diurnal variation in cravings. Specifically, abstinent smokers experienced lower cravings early and later in the day if they received metacognitive psychoeducation. An alternative directional hypothesis suggests that withdrawal symptoms increase beliefs. Consistent with this, changes in negative affect predicted changes in metacognitive beliefs. Quitting smoking did not causally impact beliefs, but successfully abstinent smokers showed a greater decline in overly negative craving interpretations. Regarding metacognitive responses, cessation increased use of reappraisal, distraction and suppression, but there were no differences in strategies used by successful and unsuccessful abstainers. Only rumination predicted smoking one month later. Overall, results provide partial support for metacognitive models. Causal effects of beliefs on withdrawal symptoms (and vice versa) were not detected but nonexperimental results imply a bidirectional relationship. Future research on rumination and certain types of metacognitive beliefs is warranted. Examination of clinical applications of metacognitive models would also be valuable, particularly among depressed smokers or as an adjunct to behavioural approaches to smoking cessation.
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Previous research has consistently shown that Asian-heritage individuals report higher levels of social anxiety compared to their European-heritage counterparts. The goal of this study was to examine whether culturally-influenced social standards, social self-efficacy, and perceived social status account for elevated reports of social anxiety in East Asian-heritage (EAH) individuals. Drawing from cognitive and evolutionary models of social anxiety, two competing hypotheses that encompassed these social contextual variables were tested to explain ethnic differences in social anxiety: the Asian socialization hypothesis proposed that higher self-reported social anxiety in EAH individuals are related to their greater exposure to East Asian cultural values, while the cultural discrepancy hypothesis posited that Asian-Western differences in social anxiety are associated with the bicultural experience of cultural and/or ethnic discrepancy with mainstream Western culture. In a cross-national sample of East Asian- and European-heritage students living in Canada (Ns = 280 and 103, respectively) and East Asian students living in Korea and China (N = 309), participants completed self-report questionnaires that measured social anxiety, depression, and social contextual factors (i.e., cultural norms, social self-efficacy, and perceived social status). Measures of acculturation and self-construal were also included to confirm that the groups differed on cultural values. Planned contrast analyses demonstrated relatively strong support for the cultural discrepancy hypothesis, in which bicultural East Asian groups (i.e., 1st- and 2nd-generation EAH individuals) reported greater social anxiety and depression, as well as lower initiation social self-efficacy and perceived social status compared to members of unicultural groups (i.e., European-heritage and overseas East Asian groups). However, social self-efficacy and perceived social status did not appear to mediate the elevated social anxiety levels in bicultural East Asians. Findings showed limited support for the Asian socialization hypothesis. Overall, the results suggest that higher reports of social anxiety in bicultural East Asians may be associated with the experience of cultural and ethnic discrepancy with Western mainstream culture, and conceptualized as a part of the experience of acculturative and/or bicultural stress. Findings from this study suggest that the role of cultural discrepancy in elevated social anxiety warrants further investigation using longitudinal or experimental designs.
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Recent theories posit that cognitive factors explain the development and maintenance of contamination fears associated with obsessive compulsive disorder (OCD). Few studies to date have aimed to establish causality or temporal precedence for cognitions predicting OCD-relevant distress and avoidance. The current study used a prospective design to assess threat appraisals, personality traits, and obsessive compulsive symptoms in an unselected sample of university students and community members (N = 105) several days prior to a contamination behavioural approach task (BAT) in a public washroom. Results of the hierarchical regressions demonstrated that prospective danger appraisals significantly predicted both disgust and avoidance on the BAT, even when controlling for neuroticism, disgust sensitivity, and OCD symptoms. In contrast, looming germ spread appraisals and responsibility appraisals were not significant predictors of the BAT. Results from in vivo distress ratings and implicit reaction time data indicated that disgust is more strongly associated with contaminants compared with anxiety. The findings of this research suggest that psychological treatment for contamination concerns should include monitoring of disgust as a process and outcome variable in exposure paradigms, and focus on reappraisal of danger estimates related to disease in cognitive paradigms.
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Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
The dysfunction associated with hoarding behaviour sometimes requires intervention from community agencies to reduce risks to occupants and the public. Unfortunately, current measures do not reflect a shared understanding of aspects of the home that are necessary for community service providers to assess in cases of hoarding. Providers differ in their understanding of risks in the home, as they do not consistently use the same measures to conduct assessments, nor are there standard guidelines of what needs to be assessed in hoarded homes. This study aimed to develop a measure that would reflect a collective understanding of essential hoarding-related health and safety risks in the home that require intervention. Study 1 involved a Delphi survey to create a list of items that are critical to assess in hoarded homes. This study identified 32 environmental risk factors to include in the risk assessment measure. Once this part was complete, the Home Environment Assessment Tool for Hoarding (HEATH) was created with these items grouped into five domains. In Study 2, another group of experts assessed the content validity of the resulting measure using the Content Validity Index method. At least 80% of participants endorsed clarity, relevance, and practicality of every item. The index for the overall scale was 0.996, providing strong evidence of content validity. These studies played an essential role in the creation of a risk assessment measure that can improve communication between agencies, track changes from interventions, and standardize risk assessment in hoarded homes.
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Our lives are interwoven with artefacts of our own creation. While these artefacts are (objectively speaking) inanimate, research on anthropomorphism suggests that we sometimes perceive them to have a mind. For people who hoard this tendency to anthropomorphize their possessions is particularly heightened. Hoarding is characterized by difficulty discarding possessions of little to no apparent value, excessive acquisition of objects, and levels of clutter in the home that cause functional impairment and distress. While it is clear that strong emotional reactions to discarding objects play a role in the development and maintenance of hoarding, it is less clear what the nature of these emotions are. The heightened anthropomorphism associated with hoarding suggests that some of these emotions may be social in nature. People who hoard may find it difficult to part with possessions because they have empathy and concern for their objects. Since much of the research on anthropomorphism has focused on more cognitive aspects of social cognition, I created a scale – the Empathy and Concern for Objects scale (or ECO) – to measure this affective anthropomorphism. Across two studies (N=704), I assessed the psychometric properties of the ECO, its discriminant validity, association with hoarding, and I provide an initial test of models that could explain this association. The ECO demonstrated good psychometric properties, correlated moderately with other measures of anthropomorphism, predicted self-reported hoarding, and mediated the relationship with hoarding and negative affectivity, loneliness, and general empathy.
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Understanding the complexity of hoarding cases is a challenge faced by clinicians and communities alike. Although classified as a mental disorder, the clutter generated by hoarding behaviours does not solely affect the individual; these behaviours are of great concern for society in general. The two approaches to assessing and responding to hoarding disorder taken by research and communities are considerably different. Research has focused on assessing the internal experience of those with hoarding disorder, as well as developing treatments to reduce hoarding behaviours. In contrast, communities across North America have been focused on assessing the public safety threats posed by hoarding cases and responding through a harm reduction approach. The current study bridged the gap between these approaches through a research collaboration with the Vancouver-based Hoarding Action Response Team. Due to the complexity of cases, community-based hoarding teams use a case-by-case approach to address hoarding-related problems. This study conducted a cluster analysis to identify subgroups of hoarding cases and propose intervention targets. Data were collected from the team’s work (e.g., health records, team triage meetings, fire data management system). The current study identified five clusters: Cohabiting in Squalor, Socially Engaged, Isolated at Home, Medically Complex, and Difficult to House. All clusters had a similar degree of clutter, but presented distinct challenges necessitating different interventions. Results from this study will lead to more efficient triaging, network coordination, and evidence-based decision-making on the part of policymakers.
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Despite popular media portraying hoarding to be a problem of extremely poor housekeeping, most hoarded homes are relatively clean – large amounts of stuff just prevent the home from being functional. Some hoarded homes, however, develop poor living conditions like filth or disrepair. To date, little is known about how homes end up this way. The current study identified unique predictors and generated ideas about complex processes involved in the development of poor living conditions in hoarding. Three community agencies shared in-home assessment data for mainly involuntary clients with problematic living conditions, such as hoarded or filthy homes. These community agencies were the Metropolitan Boston Housing Partnership (n=115) in Boston, MA, the Hoarding Action Response Team (n=137) in Vancouver, BC, and the Hamilton Gatekeepers Program (n=209) in Hamilton, ON. Each site completed in-home assessments from 2010-2014 to evaluate client characteristics (lack of insight, social isolation, state of mind) and conditions of the home (number of pets, clutter accumulation, unusable bathrooms or kitchens) using the HOMES: Multidisciplinary Hoarding Risk Assessment, the Clutter Image Rating Scale, or a similar measure. Site-specific regression analyses identified unique predictors of poor living conditions. Clients with high clutter accumulation were at increased risk for squalor at all three sites, while kitchen or bathroom problems uniquely predicted squalor at two sites. Within two agencies, number of pets was also a consistent predictor of one indicator of squalor, the presence of urine or feces. Few clients had household disrepair (9-12% within sites), but findings hint that disrepair is associated with high clutter accumulation. Findings related to poor insight being a predictor of squalor were mixed.This is the first study to directly examine poor living conditions in hoarding. Replicated study findings across sites suggest that common features of hoarding, such as clutter accumulation and unusable rooms, are unique predictors for squalor. Results from this study can help community agencies that deal with problematic living situations prioritize intervention goals, especially if staff believe clients are at risk for poor living conditions.
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Many people with hoarding problems have never been married and live by themselves. Further, treatment-seekers tend to be elderly, which puts them at special risk for social isolation. Research has established strong links between social support and many aspects of psychological health, but the role of social support in hoarding has not yet been explored. Does excessive clutter drive away people who care? Does living alone provide freedom to accumulate clutter? How social support is provided and received is also relevant. Although family members or healthcare workers may intend to minimize health and safety risks associated with hoarding behaviour, actions they intend to be supportive may be delivered insensitively or inappropriately. Previous research has found that hoarding is a source of family burden and distress. As a result, hoarding may be related to interpersonal conflict. This study investigated (1) social integration, the degree to which someone is involved in a broad range of relationships, (2) perceived support, the amount of support perceived to be available if need arises, (3) received support, the amount of support perceived to have been obtained, and (4) social conflict, which broadly includes a range of negative social interactions. Seventy-eight participants with a range of hoarding symptoms were surveyed online. The relations among hoarding symptoms and four aspects of social support were examined. The effect of depression was considered, as it is highly comorbid with hoarding and may account for some aspects of poor social support. Hoarding was related to perceived support and social conflict, but this relationship was explained by depression. In contrast, hoarding was not related to social integration or received support. This study provides a basis for further research on social interactions in hoarding, and demonstrates the necessity in building sensitivity and awareness beyond media portrayals of hoarding, such that supportive behaviours are delivered in a thoughtful manner that minimizes conflict. Additionally, this study has implications for encouraging social integration and addressing issues of social support and conflict within hoarding interventions.
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In 1996, Frost and Hartl proposed that the excessive clutter and difficulty discarding objects characteristic of compulsive hoarding disorder may be partially explained by a cognitive deficit in the ability to efficiently categorize objects. Subsequent studies that empirically investigated Frost and Hartl’s (1996) proposed categorization deficit have been highly inconsistent in terms of whether this deficit exists and, if so, whether it is dependent on symptom severity and the personal significance of objects. The current study sought to help clarify the inconsistent pattern of past research by replicating and extending a study by Luchian, McNally, and Hooley (2007) to contrast population and task differences between previous studies. The current study compared healthy controls (n = 35), individuals with subclinical symptoms of compulsive hoarding (n = 30), and individuals with clinical symptoms of compulsive hoarding disorder (n = 20), on sorting tasks involving participants’ personal possessions, typically hoarded objects, and the collection of trivial objects employed in the Luchian et al. sorting task. Results suggest that both the clinical and subclinical groups show tendencies towards underinclusive categorization. However, this effect was not strong. A larger difference was found between groups on distress and latency; the clinical group took longer to complete sorting tasks and exhibited greater distress while engaging in sorting tasks than both other groups. These results suggest that traditional sorting tasks may not be sufficient for examining categorization difficulties in compulsive hoarding, and that behavioral avoidance is a more plausible mechanism for the disorganization of hoarded homes than is underinclusive categorization.
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