ACT process measures: specificity and incremental value

A number of objective personality questionnaires have been published which aim to measure the six processes related to Acceptance and Commitment Therapy's model of treatment (acceptance, defusion, present moment awareness, self-as-context, values, and committed action). These measures operationally define these hypothesized processes in research settings. However, little research has been done to investigate whether these processes, as measured by these questionnaires, are differentiable from each other or from other, seemingly similar constructs such as distress tolerance and coping styles. Additionally, it is unclear whether these questionnaire measures have differing relationships with other potentially relevant constructs, such as psychopathology, functioning, and personality. The structure of these process measures was investigated across two participant samples. A multi-trait structure of ACT processes was found, with three higher order dimensions consisting of psychological inflexibility/cognitive fusion, mindfulness, and avoidance, as well as a number of distinguishable lower order traits. This structure was found across multiple samples, and measures of these factor analytically-derived traits were found to have incremental validity and to be distinguishable from other, superficially similar psychological processes. These results provide guidance for measurement selection and suggest future directions for scale development. Relevance to treatment outcome research is also discussed.