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Thesis defences

PhD Oral Exam - Hannah C. Levy, Psychology

Experimental investigations of the judicious use of safety behaviour in exposure therapy for contamination fear

Date & time

Friday, November 6, 2015
8 a.m. – 11 a.m.


This event is free


School of Graduate Studies


Sharon Carey
514-848-2424, ext. 3802


Psychology Building
7141 Sherbrooke W. Room 123

Wheelchair accessible


When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.


Compulsive washing and contamination fear are among the most common symptoms of obsessive-compulsive disorder (OCD). Exposure and response prevention (ERP) is an effective treatment for OCD, but a substantial proportion of clients/patients refuse this treatment entirely or drop out prematurely. A proposed solution involves the judicious use of safety behaviour to enhance the acceptability of ERP. However, to this author’s knowledge, there are currently no published guidelines for the judicious use of safety behaviour in exposure, and questions remain about how best to incorporate safety behaviour into existing treatments. For instance, which kinds of safety behaviour may be beneficial in treatment, and which may be harmful? Who decides when to eliminate the safety behaviour during treatment, the client/patient or the therapist? The present studies made a first attempt at addressing these questions. In the first study, a clinical sample of individuals with contamination-related OCD (N = 60) was randomized to receive an exposure session with no safety aid (ERP), a routinely-used safety aid (RU), or a never-used safety aid (NU). Significant reductions in contamination fear severity were observed in all conditions. However, participants in the NU condition demonstrated the lowest self-reported contamination fear severity at post-treatment. Further, the NU condition received the highest acceptability and anticipated adherence ratings. In the second study, a subclinical sample of undergraduate students (N = 100) was assigned to complete an exposure session for contamination fear under one of three fading conditions: participant-initiated, experimenter-initiated (based on time), or experimenter-initiated (based on participant-reported distress levels). Compared to the experimenter initiated time-based condition, the participant-initiated condition demonstrated significantly greater reductions in obsessive beliefs and peak fear, as well as marginally higher treatment expectancy ratings. There were no differences in outcome or acceptability between the participant-initiated and experimenter initiated distress-based conditions. The results of these studies are discussed in terms of the cognitive-behavioural theory and treatment of anxiety and related disorders, and of the potential benefits of judiciously incorporating safety behaviour into effective treatments

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