Laser-Induced Pain-Related Brain Potentials and Sensory Pain Ratings in High and low Hypnotizable Subjects During Hypnotic Suggestions of Relaxation, Issociated Imagery, Focused Analgesia, and Placebo

Pain reports and amplitudes of painful argon laser-induced brain potentials were obtained for 10 high and 10 low hypnotizable volunteers following placebo and a randomized sequence of four hypnotically induced conditions of (a) neutral hypnosis, (b) deep relaxation, (c) pleasant dissociated "out of body" imagery, and (d) focused analgesia of the hand. Both high and low hypnotizable subjects exhibited significant reductions of reported pain during conditions of neutral hypnosis, relaxation, dissociated imagery, and focused analgesia. High hypnotizable subjects displayed significantly greater reductions than low hypnotizables in all conditions except placebo. Both high and low hypnotizables exhibited significant reductions of reported pain in all five conditions as well as in the posthypnotic condition, when amplitudes of evoked potentials were compared to the prehypnotic baseline. Only the high hypnotizable group showed significant reductions in amplitudes when the data were recalculated to reflect relative changes compared to the average amplitude of the pre- and postconditions to compensate for a possible habituation effect indicated by the significantly lowered amplitudes in the posthypnotic condition. The results are discussed in light of a number of hypotheses concerning mechanisms of hypnotic analgesia.