Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. Scott Gaynor

Second Advisor

Dr. Amy Naugle

Third Advisor

Dr. Amy Damashek

Fourth Advisor

Dr. C. Dennis Simpson


Acceptance and commitment therapy, psychological flexibility, behavior therapy, cognitive defusion, Drexel Defusion Scale, psychometrics


Acceptance and Commitment Therapy (ACT) seeks to develop psychological flexibility through the engagement of the six interrelated processes. Four processes employ mindfulness and acceptance strategies and consist of acceptance, defusion, present moment awareness, and the contextualized self. Two other processes, values and committed action, are grouped with present moment awareness and the contextualized self and are termed behavior change strategies. One issue encountered by contemporary behavioral approaches in general, and ACT in particular, is the measurement of the proposed processes. Measurement is complicated by the functional nature of some of the repertoires described making the development of instruments for assessment challenging. The present study focuses on defusion, the ability to disentangle from language and its byproducts. The development of reliable and valid instruments is essential for research and clinical application. Forman, Herbert, Juarascio, Yeomans, Zebell, Goetter, and Moitra (2012) presented initial psychometric data on the Drexel Defusion Scale (DDS), a measure of defusion. In the present study data were collected from a large undergraduate population across three phases (N = 306, 325, 256, respectively) to explore the psychometric properties of the DDS. Results were consistent with the ACT model and Forman et al. in that the DDS correlated moderately with the Acceptance and Action Questionnaire-II (r = -.30, p < .001) and quality of life (r = -.30, p < .001), but with the latter two correlating more strongly with each other. A questionable test-retest reliability statistic (r = .62, p < .001) was found suggesting some potentially temporal variability in responding. The two-factor structure found by Forman et al. (2012) was generally replicated across samples, genders, and ordering of the questions; however, one item appeared somewhat inconsistent. Both the DDS and AAQ-2 items were entered simultaneously into an exploratory factor analysis. The items of the AAQ-2 consolidated into their own factor; but the DDS now sorted into 3 factors. The implications for the ACT Hexaflex model are explored as is the need for future research to explore the interaction of the DDS with other related-ACT measures. An important need is to study the measure with diverse populations.

Access Setting

Dissertation-Open Access