Hypnotic susceptibility and experimental pain reduction

We exposed 24 subjects high in hypnotic susceptibility and 24 subjects low in hypnotic susceptibility to a cold-pressor pain stimulus under either hypnotic or waking conditions, using each of two pain-reduction strategies (analgesia and distraction) separately. Trance depth level was held constant for hypnotized subjects. We used pain-tolerance levels as measures of pain, and we analyzed them by survival analysis. High susceptibles reported significantly lower pain ratings and kept their hands immersed longer in the cold water than low-susceptible subjects. There were no significant differences between hypnotic and waking condition subjects or between the different strategies. We have discussed the results in terms of a relationship in the literature between choice of experimental design (between-subjects or within-subjects) and the effectiveness of a hypnotic induction for suggested pain reduction.