CREDIBILITY AND OUTCOME OF COGNITIVE-BEHAVIORAL AND PSYCHODYNAMIC-INTERPERSONAL PSYCHOTHERAPY

Depressed psychotherapy clients (N = 117) rated the treatment principl e credibility of cognitive-behavioural (CB) and psychodynamic-interper sonal (PI) before they were randomly assigned to receive either eight or 16 sessions of one of these treatments, and they rated their expect ations of the treatment to which they were assigned immediately before (initial credibility) and immediately after their first session (emer gent credibility). Results indicated that before they were assigned to a treatment, clients rated CB treatment principle credibility higher than PI treatment principle credibility. After assignment, however, cl ients rated initial credibility similar regardless of whether they wer e assigned to CB or PI therapy, and their ratings of emergent credibil ity increased to a similar degree from immediately before to immediate ly after the first session in both treatments. Clients' endorsement of CB and PI treatment principle credibility predicted improvement in PI therapy but not improvement in CB therapy. Initial and emergent credi bility of clients' assigned treatment predicted improvement for client s who received eight sessions of therapy, but not for clients who rece ived 16 sessions of therapy. The implications of these findings are di scussed.