Restricted environmental stimulation and the enhancement of hypnotizability: Pain, EEG alpha, skin conductance and temperature responses

Abstract

Restricted environmental stimulation procedures were used with 10 Ss. The Stanford Hypnotic Clinical Scale: Adult (SHCS) of Morgan and J. R. Hilgard (1975), modified to include a posthypnotic suggestion for an analgesic reaction, and pain threshold and tolerance tests were administered prior to restricted environmental stimulation technique (REST), immediately after REST, and 10–14 days later. Occipital EEG alpha, skin conductance, and peripheral, core, and chamber temperature data were collected prior to, during, and after REST. A control group of 10 Ss was used to assess the effects of repeated hypnosis upon susceptibility scores and demand characteristics of the experiment. Multivariate analysis of variance results showed SHCS and pain tolerance scores to be significantly enhanced for Ss exposed to REST immediately after and 10–14 days later. Orne's (1959) postexperimental inquiry technique did not reveal experimental demand characteristics which might account for the results. EEG alpha density increased significantly in REST, but the increase was not progressive during the REST period. The maintenance of hypnotizability and pain tolerance at follow-up failed to support Reyher's (1964) theory of brain function and behavioral regulation. E.R. Hilgard's (1977) neodissociation interpretation combined with J.R. Hilgard's (1974, 1979) imaginative involvement findings is viewed as a possible explanation.