Thin slice ratings of client characteristics in intake assessments: Predicting symptom change and dropout in cognitive therapy for depression

•We assess personality using thin slice ratings of clients' intake assessments.•Thin slice ratings predicted dropout and treatment outcome.•Ratings of clients' therapy interest and neuroticism predicted lower dropout odds.•Ratings of extraversion predicted a faster rate of symptom change.•Ratings of Avoidant and Schizoid traits predicted slower rates of symptom change.

Thin slice ratings of personality have been shown to predict a number of outcomes, but have yet to be examined in the context of psychotherapy. In a sample of 66 clients participating in cognitive therapy for depression, we examined the predictive utility of thin slice rated pre-treatment client traits. On the basis of short video clip excerpts (i.e., thin slices) of intake assessments, trained observers rated clients on personality characteristics and specific personality disorder (PD) traits. Clients' therapy interest and neuroticism predicted lower odds of dropout. Ratings of extraversion predicted greater symptom change across treatment; ratings of clients' Avoidant and Schizoid PD traits predicted less marked symptom improvement. Ratings of agreeableness and likeability also predicted greater symptom change, but these relations were only significant in one of two analytic approaches used. Evidence for the predictive validity of thin slice ratings was generally stronger than that observed for self-reported PD traits and PD status. Moreover, these self-report and diagnostic assessments failed to account for the thin slice-outcome relations identified. Findings support the clinical utility of quick, thin slice impressions of clients, as these ratings could be used to identify clients with a high risk of dropout or poor treatment outcome.