A psychophysiological differentiation between hypnotic behaviour and simulation.

Psychophysiological differentiation between conditions of hypnosis and simulation were examined with markers evolved from a series of experiments charting neuropsychophysiological accompaniments of hypnotic behaviour. Eighteen subjects participated in two sessions in which bilateral electrodermal activity was monitored to moderate intensity tones. Measurement in Session I, a Baseline-Control, of individual variation in rates of habituation of orienting responses, non-specific responses and tonic levels of skin conductance, enabled allocation of matched groups to Session II in which the same auditory stimuli were mixed with a taped hypnotic induction. Half the subjects were instructed to fake hypnosis and the others to comply. In session II the groups were differentiated as follows: (1) rate of habituation to the tones was retarded in the simulation condition and facilitated in the hypnosis condition compared with baseline; (2) the incidence of non-specific electrodermal responses was elevated in simulators after instructions to 'fake hypnosis'; (3) right-hand levels of skin conductance were elevated in simulators; (4) all but one subject in the hypnosis condition admitted to hearing the tones whereas all but one in the simulation condition claimed not to have heard them.