Date of Award


Document Type

Campus Access Thesis

Degree Name

Master of Arts (MA)


Clinical Psychology

First Advisor

Lizabeth Roemer

Second Advisor

Alice S. Carter

Third Advisor

Laurel Wainwright


As a field, we lack information about specific mechanisms of change that occur throughout treatment (Kazdin, 2007). Identifying these mechanisms would help to streamline evidence-based approaches, increase treatment response rates, and aid in the dissemination and implementation of evidence-based approaches in diverse contexts. The current study examined reductions in experiential avoidance (EA), which refers to attempts to control or eliminate distressing internal experiences, regardless of behavioral consequences, in participants with a principal diagnosis of Generalized Anxiety Disorder (GAD) receiving either Acceptance-based Behavior Therapy (ABBT) or Applied Relaxation (AR). Reductions in EA have been hypothesized to be a mechanism of change in mindfulness and acceptance-based interventions, and may also be relevant in more broadly defined Cognitive Behavioral Therapies (CBTs). Participants scores across treatment on the Acceptance and Action Questionnaire (AAQ), which measures EA, were used to calculate a slope and intercept value for each participant, which were used as predictors in a series of linear regressions examining the impact of reductions in EA over the course of treatment on symptom and quality of life outcomes. Results indicated that steeper slope in EA across treatment significantly predicted worry (PSWQ), anxious arousal (DASS-Stress), and quality of life (QOLI) at post-treatment across both treatment conditions. AAQ intercept, or where participants started in terms of EA also significantly predicted all outcomes at post-treatment. Given recent discussions about the definition and measurement of EA, we re-ran all analyses with a more narrow definition of experiential avoidance focused only on attempts to avoid or control internal experiences. These exploratory analyses indicated this AAQ slope was still a significant predictor for all three outcomes across both treatment conditions. However, AAQ intercept was no longer a significant predictor for any of the outcomes. These results contribute to a growing body of literature on common mechanisms of change across traditional CBTs and mindfulness and acceptance-based approaches. Future research is needed to further clarify the definition and measurement of EA. Given that EA appears to be an important treatment target across CBTs broadly, future research should examine ways to disseminate and implement approaches that foster reductions in EA in diverse contexts.


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