Abuse of the drug metaphor in psychotherapy process-outcome research

Abstract

Slow progress in psychotherapy process-outcome research may be attributable to researchers' implicit subscription to the “drug metaphor,” which suggests that psychotherapy consists of active ingredients supplied by the therapist. If a process component is an active ingredient, then a high level of it is supposed to yield a positive outcome, and failure to do so implies that the component is inert. In this article, we critique some of the drug metaphor's implicit assumptions — that process and outcome are distinct phenomena; that component names signify pure ingredients; that we are measuring the active ingredients; that the active ingredients are contained in the therapist's behavior; that the dose-response curve is ascending and linear; that the best way to demonstrate a psychotherapeutic procedure's efficacy is by controlled clinical trial; and that a process component's efficacy is shown by its correlation with outcome.