Hypnotic suppression of conditioned electrodermal responses.

Abstract

Conditioning and its relationship with hypnosis has primarily been the work of Russian investigators. Pavlov (1927) concluded hypnosis was an inhibitor of motor activity, and the later work of Edmonston (1968) appears to support Pavlov's view that voluntary functions are inhibited by hypnotic induction, whereas nonvoluntary functions appear not to be. The experiment reported focuses on the extent to which hypnosis interacts with previously conditioned electrodermal responses, i.e., a nonvoluntary Function. Five subjects (4 women and 1 man), all undergraduates in psychology, were randomly selected from a larger experimental group of 12 subjects (8 women and 4 men) who were previously aversively conditioned to the numerical figure '8' (see Griffiths, Gillett, & Davies, 1987). Having already been conditioned, the subjects were then hypnotized using a standard eye elevation and standard deepening technique. Hypnotized subjects were then re-exposed to the visually presented conditioned stimuli and their electrodermal responses were measured. These responses were then compared against each subject's own nonhypnotic responses. Analysis showed that during hypnosis, electrodermal responses as measured in mm deflections from the baseline were significantly lower (hypnotic M = 38.3 mm; nonhypnotic M = 101.3 mm; SD = 91.9 mm), thus previously conditioned electrodermal responses were suppressed (t = 2.39, p<.05). This result contradicts the findings of Edmonston (1968) who found that neutral hypnosis does not influence conditioned electrodermal responses, and Pavlov's (1927) theory of hypnosis and conditioning, i.e., that hypnosis inhibits motor (voluntary) conditioned responses but not nonmotor (involuntary) conditioned responses. Although the sample of five was small, data clearly demonstrated that previously acquired conditioned responses were suppressed during hypnosis. This finding raises questions about the validity of Pavlov's inhibition theory of hypnosis and predictably begs the question as to what hypnosis is and what it actually does.