Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)



Committee Chair(s)

Michael P. Twohig


Michael P. Twohig


Tyson S. Barrett


Michael E. Levin


Karen Muñoz


JoAnn T. Tschanz


Clinical perfectionism is characterized by rigidly pursuing unrealistically high standards on which self-worth is contingent and experiencing distress when these standards are not met. Because clinical perfectionism is associated with many psychological diagnoses, understanding how to treat it may help streamline available treatments. The aim of this dissertation was to test the effect of acceptance and commitment therapy (ACT), a cognitive-behavioral therapy, on 53 individuals with clinical perfectionism. Participants in the ACT group received 10 therapy sessions and those in the control group were on a waitlist for 14 weeks. The first study supported the effectiveness of ACT relative to the waitlist control group with respect to perfectionism severity, quality of life, and general symptom distress. The second study showed changes in psychological inflexibility and self-compassion explained improvements in quality of life and concern over mistakes, respectively. It also found a variable effect of baseline psychological inflexibility on response to treatment depending on the outcome tested. In contrast, average self-compassion was generally associated with better outcomes in ACT. Neurological results from the third study suggest receiving ACT was associated with greater cognitive efficiency while performing error-prone tasks and decreased responsivity to emotionally meaningful stimuli. In addition, changes in brain activation were not linked to changes in self-report outcomes. Collectively, this dissertation examined not only the efficacy of an intervention focused on a maladaptive behavioral pattern like clinical perfectionism but also how and for whom such a therapy works.



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