ABSTRACT
Objective: Empirical findings on self-serving biases amongst psychotherapists are inconsistent. We tested in a large naturalistic data set, if therapists are prone to illusory superiority when estimating their patients' outcome and whether this effect is buffered by therapists' effectiveness. Method: A post-hoc analysis with N = 69 therapists, who treated N = 1080 patients, was conducted. Therapists' and patients' mean ratings for therapeutic improvement in the Clinical Global Impression Scale (CGI) were compared. Using a multilevel modelling approach, we further investigated the relation between the patient-therapist divergence in the CGI and actual therapeutic change in the Global Severity Index (GSI) of the Brief Symptom Inventory and in the Satisfaction With Life Scale (SWLS). Results: Ratings in the CGI did not show significant differences between patients' and therapists' assessment of therapeutic change. Lower estimations by therapists, compared to patients' self-report, were associated with greater therapeutic change in GSI and SWLS. Conclusions: Therapists, on a whole, did not seem to be prone to illusory superiority when assessing therapeutic outcome. Contrary, the more modest the therapists' estimation of therapeutic outcome was, the greater the actual therapeutic change.
