Mediation and moderation of psychological pain treatments: response expectancies and hypnotic suggestibility.

The mediator role of response expectancies and the moderator role of hypnotic suggestibility were evaluated in the analogue treatment of pain. Approximately 1,000 participants were assessed for hypnotic suggestibility. Later, as part of a seemingly unrelated experiment, 188 of these individuals were randomly assigned to distraction, cognitive-behavioral package, hypnotic cognitive-behavioral package, hypnotic analgesia suggestion, placebo control, or no-treatment control conditions. Response expectancies partially mediated the effects of treatment on pain. Hypnotic suggestibility moderated treatment and was associated with the relief produced only by the hypnotic interventions. The results suggest that response expectancies are an important mechanism of hypnotic and cognitive-behavioral pain treatments and that hypnotic suggestibility is a trait variable that predicts hypnotic responding across situations, including hypnosis-based pain interventions.