The impact of treatment components suggested by the psychological flexibility model: a meta-analysis of laboratory-based component studies.

An important aspect of psychotherapy research is the examination of the theoretical models underlying intervention approaches. Laboratory-based component research is one useful methodology for this endeavor as it provides an experimental means of testing questions related to intervention components and the change process they engage with a high level of control and precision. A meta-analysis was conducted of 66 laboratory-based component studies evaluating treatment elements and processes that are suggested by the psychological flexibility model that underlies Acceptance and Commitment Therapy (acceptance, defusion, self as context, committed action, values, and present moment), but also touches on a variety of contextual forms of cognitive behavior therapy. Significant positive effect sizes were observed for acceptance, defusion, present moment, values, mixed mindfulness components, and values plus mindfulness component conditions compared to inactive comparison conditions. Additional analyses provided further support for the psychological flexibility model, finding larger effect sizes for theoretically specified outcomes, expected differences between theoretically distinct interventions, and larger effect sizes for component conditions that included experiential methods (e.g., metaphors, exercises) than those with a rationale alone. Effect sizes did not differ between at-risk/distressed and convenience samples. Limitations with the meta-analysis and future directions for laboratory-based component research are discussed.