Disabuse of the drug metaphor: Psychotherapy process-outcome correlations.

The drug metaphor suggests that if a process component (e.g., interpretation) is an active ingredient of a successful psychotherapy, then administering a relatively high level of it should yield a relatively positive outcome, and levels of the process component and the outcome should be correlated across clients. Measures of 5 theoretically relevant, reliably measured verbal process components were compared with the rate of change in 3 standard symptom intensity measures across the brief treatments of 39 (mainly depressed) psychotherapy clients. The expected significant process-outcome correlations were not found. These results are discussed as they illuminate some misleading assumptions that underlie many conventional studies of psychotherapy process and outcome.