Submission note: A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Clinical Psychology [to the] School of Psychological Science, Faculty of Science, Technology and Engineering, La Trobe University, Bundoora.
Collaborative empiricism (CE) is a key CBT process, in which the client and therapist collaborate to empirically explore the client’s cognitions and cognitive processes. The aims of this study were to develop and psychometrically evaluate the first measure of CE in the literature, the Collaborative Empiricism Scale (CES), and use the measure to examine whether CE predicts reduction in depression severity in CBT for depression. The CES employs a novel design and rating methodology, allowing the rating of collaboration and empiricism at multiple levels, and at multiple times, within each therapy session. A theoretical model of CE is proposed that seeks to explain the motivational aspects of the construct, and integrate the collaborative and empirical elements of CE. Three studies are reported. In Study 1, 30 expert CBT researchers and practitioners evaluated the draft CES via an online feedback questionnaire, in a process consistent with the Delphi method. Experts rated the CES very highly for content validity, ecological validity, and ability to capture variance in CE, and highly for clarity. Study 2 reports on pilot testing of the scale. In Study 3, psychometrics of the CES are reported, and CE is examined as a predictor of depression severity in a sample of 44 adults, at three time points, with a total of 3548 ratings of empiricism and collaboration across 132 therapy sessions. Reliability of the CES was high, and concurrent validity demonstrated with the Cognitive Therapy Rating Scale. Collaborative empiricism was found to predict reduction in depression severity at termination, after controlling for pre-therapy depression, the working alliance, and therapist competence. A medium effect size of CE on depression was obtained (R2 equals .088), larger than that reported in the literature for the working alliance or therapist competence. This effect was maintained at 6, 12, 18, and 24 months post-therapy.