Daniel

The Relationship between Psychological Flexibility and Treatment Outcomes

Melissa Daniel

Abstract

This study explores changes in psychological flexibility as a result of psychotherapy, and ways that those changes may be related to the overall treatment outcome. It has been proposed that the changes in psychotherapy are due to common factors, such as therapeutic alliance, rather than intervention-specific factors (Wampold & Imel, 2015). The introduction of psychological flexibility as a therapeutic focus in Acceptance and Commitment Therapy (ACT)has raised the question of its role in the process of change. This study aims to understand whether psychological flexibility may be a central ingredient in change, or another measure of patient global distress. Data from a psychotherapy outcomes project were compiled which measured patients’ (n = 1664) global functioning, social functioning, global distress, and psychological flexibility (as measured by items from the Acceptance and Action Questionnaire II) in various stages of treatment. Factor analysis showed flexibility to load on a common factor of improvement, and the three items had a strong alpha of .78. Correlational analysis showed that changes in global functioning and changes in psychological flexibility were significant and strong predictors of change in symptoms (r =.73 for symptoms and .69 for functioning, exceeding predictions based on reliability, both at p < .0001). Flexibility was second only to change in functioning in predicting symptom reduction. These findings support the hypothesis that increasing psychological flexibility may be a key factor in positive changes from psychotherapy. Implications for future developments in treatment and interventions from an ACT perspective are discussed.

Keywords: psychological flexibility, treatment outcomes, acceptance and commitment therapy