Placebo psychotherapy: synonym or oxymoron?

Abstract

Contrary to some recent claims, the placebo effect is real and in some cases very substantial. Placebo effects can be produced or enhanced by classical conditioning, but consistent with virtually all contemporary conditioning theories, these effects are generally mediated by expectancy. Expectancy can also produce placebo effects that are inconsistent with conditioning history. Although expectancy also plays an important role in psychotherapy outcome, the logic of placebo-controlled trials does not map well onto psychotherapy research. The idea of evaluating the efficacy of psychotherapy by controlling for nonspecific or placebo factors is based on a flawed analogy and should be abandoned.