The effect of posthypnotic suggestion and task difficulty on adherence to health-related requests.

The effects of posthypnotic suggestion on health-related behavior, using a behavioral measure of adherence, were investigated. Three hundred twenty-three students covering the full range of hypnotic suggestibility were prescribed an easy (mood rating) or a difficult (physical activity) task. Participants were randomly assigned to receive either a) hypnosis with posthypnotic suggestions to facilitate performance of the assigned task or b) a social request to perform the assigned task. There were significant effects for type of task and hypnosis, revealing that participants adhered significantly more to the easy task and that hypnosis decreased task adherence. Hypnotic suggestibility did not predict adherence, and its interaction with posthypnotic suggestion was not significant. These results suggest that posthypnotic suggestion may decrease adherence rates regardless of participants’ suggestibility level.