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Cannabis use has been associated with various psychosis outcomes, including psychotic disorders, the clinical high risk period of psychosis, and subthreshold measures of psychotic symptoms in non-clinical samples, such as attenuated positive psychotic symptoms (APPS). The present study examined whether individual- and contextual-level factors account for the relationship between cannabis use and psychosis. Specifically, we hypothesized that the relationship between cannabis and psychosis would be mediated by social functioning; negative, depression, anxiety, and aggression symptoms; context of cannabis use; and motivations for cannabis use. Nine hundred and forty-five young adults ages 18-35 years (M = 20.1 years, 24.4% male) completed self-report questionnaires: the Prodromal Questionnaire, Marijuana Use Form, Social Functioning Scale, Center for Epidemiologic Studies Depression Scale, State-Trait Anxiety Inventory-Trait Form-Anxiety Subscale, Social Phobia Scale, Life History of Aggression Scale, Reasons for Use scale, and Drug Use Frequency questionnaire. Psychosis outcomes included a dimensional measure of APPS and a dichotomous measure indicating potential higher/lower risk for psychosis, based on number of distressing symptoms endorsed (i.e., D-APPS status). A multiple mediation framework was used, and significance of mediators was evaluated through estimating the significance of indirect effects using bootstrapped confidence intervals. Increases in negative and aggression symptoms mediated the relationship between higher cannabis use and increases in APPS. Negative and aggression symptoms, context of cannabis use, and using cannabis to cope with unpleasant affect mediated the relationship between cannabis use and high-D-APPS status. Results indicate that individual and contextual-level characteristics may contribute to the relationship between cannabis use and psychosis. / Psychology

All animals face a complex environment full of obstacles that they must overcome in order to survive and reproduce. How an individual responds to its environment is essential to overcoming such obstacles in order to maximize fitness. In my thesis, I focused on the roles of persistence and aggression in achieving fitness-relevant goals. Persistence is continuing in a course of action in spite of difficulty or resistance, and aggression is any instance where an individual uses physical, and potentially damaging, force against a conspecific. I used fruit flies (Drosophila melanogaster) as a model system to examine the ways in which males use persistence and aggression to attain fitness-relevant goals such as defending resources, gaining access to females, and mating. I first examined how a male’s age affected his persistence in courting recently mated females, who are generally unreceptive, and found that older males were more persistent than younger males (Chapter 2). Next, I showed that males of different ages differed in their courtship persistence in the presence of a competitor, and that males were able to subtly, but directly, interfere with one another’s courtship attempts (Chapter 3). I then demonstrated how males were able to use aggression in a mate guarding context to reduce the likelihood that a competitor male mated with their recent mate (Chapter 4), and as a form of resource defense to defend a desirable food patch in the presence of a potential mate (Chapter 5). Finally, I considered male persistence in the pursuit of unreceptive females as a form of male sexual aggression towards recently mated and sexually immature females (Chapters 5 and 6). Overall, my thesis work demonstrates how complex, and sometimes intertwined, the roles of persistence, aggression, and sexual coercion can be even within a ‘simple’ model organism, such as the fruit fly. / Dissertation / Doctor of Philosophy (PhD) / All animals face obstacles from their environment that they must respond to in order to survive and reproduce. In this thesis, I focused on how males use aggressive and persistent behaviours to overcome environmental obstacles. Aggression is the use of physical force against another individual, and persistence is when an individual continues in a course of action despite difficulties. I used fruit flies as a model to examine how males fight with one another over access to food and potential mates. I also studied how males persistently harass females in order to mate with them. In many experiments, I found that males use a combination of aggressive and persistent behaviours to achieve a goal. Overall, my results show that even in a simple species like fruit flies, individuals can use complex combinations of behaviours to achieve a variety of goals.

Social media has become a popular way of connecting with people, but it has also led to an increase in cyber aggression. Borderline Personality Disorder (BPD) is a condition that is characterized by retaliatory aggression, difficulty in interpersonal relationships, and high impulsivity. Those who endorse BPD symptoms experience unstable interpersonal relationships and struggle to maintain connections with others which can lead to problematic behaviors on social media like retaliatory aggression. Understanding the motivations behind those behaviors can help inform the experiences of the diagnosed population, mitigate problematic behaviors, and facilitate healthy social relationships. This study aims to explore the motivations that BPD symptom endorsers most identify with, such as self-protection, affiliation, and status, and the prevalence of retaliatory aggression on social media. The participants completed a self-report survey that measured their motivations, online revenge behaviors, and BPD symptom endorsement. Retaliatory aggression was also positively related to the status motivation. Results indicated self-protection had a moderating effect on the relationship between borderline symptom endorsement and retaliatory aggression. The findings of this study will help to strengthen existing literature about BPD features of impulsivity and reactivity and inform treatment and therapeutic methods by identifying the motivation behind retaliation for those who exhibit symptoms of BPD. It will also have clinical implications for how social media use is advised and addressed. Future research should seek to identify what other motivations are attributed to retaliatory aggression and expand the population to include more genders and cultures.

The current study aimed to test sensation seeking as a mediator in the relationship between arousal and aggression. In addition, an experimental design was used to test whether arousal can be manipulated to alter levels of sensation seeking and aggression, both measured behaviorally. A sample of 128 undergraduate students completed state and trait measures of sensation seeking and aggression, and baseline measures of physiology. It was hypothesized that trait sensation seeking would mediate the relationship between baseline physiology and trait aggression. Also, state sensation seeking would mediate the relationship between an arousal manipulation and state aggression. The results failed to support the proposed mediation models. Furthermore, the arousal manipulation was insufficient to result in sustained heart rate differences, and therefore the malleability of state sensation seeking and aggression could not truly be tested. Exploratory analyses supported an interaction between arousal and sensation seeking, such that in individuals low on experience seeking, disinhibition and boredom susceptibility, low heart rate was associated with greater aggression. These findings suggest that arousal and sensation seeking may conjointly predict aggression through moderation rather than mediation, though future studies with improved experimental designs are needed. / Ph. D.