Hypnotic analgesia, placebo analgesia, and ischemic pain: the effects of contextual variables.

Abstract

Carleton University Ottawa, Ontario, Canada In two experiments we examined the relation between hypnotic and placebo analgesia using isch- emic pain. The first experiment examined an artifact in a previously used ischemic pain stimulus. Experiment 2 investigated the relation between hypnotic and placebo analgesia using a submaxi- mum effort tourniquet technique to produce ischemic pain. High- and low-susceptible subjects re- ceived hypnotic and placebo analgesia in counterbalanced order. High-susceptible subjects who re- ceived placebo analgesia followed on a subsequent trial by hypnotic analgesia showed significant increases in tolerance from placebo to hypnotic analgesia. When presented in the reverse order, however, placebo analgesia and hypnotic analgesia led to equivalent levels of tolerance in both high- and low-susceptible subjects. A similar pattern of findings emerged for subjects' magnitude estimates of pain, but it was not related to hypnotic susceptibility. These findings indicate that both hypnotic and placebo analgesia may be contextually dependent phenomena. One of the oldest and most consistently cited explanations for the placebo effect equates placebo analgesia with