Surreptitious observation of responses to hypnotically suggested hallucinations: a test of the compliance hypothesis.

Suggestions for arm levitation and for visual, auditory, tactile, and taste hallucinations were administered twice via audiotape to a group of high suggestible students and low suggestible simulators. During one of the administrations, participants were led to believe they were alone, but their behavior was surreptitiously recorded on videotape and observed on a video monitor. During the other administration, they were observed openly by an experimenter who had not been informed about group assignment. When unaware that they were being observed, simulators were significantly less responsive to suggestion and engaged in substantially more role-inappropriate behavior. In contrast, the responsiveness of nonsimulating students was not affected by the presence of an experimenter, and they exhibited little role-inappropriate behavior even when alone. These data indicate that the responses of suggestible individuals reflect internally generated changes in experience and are not due to simple intentional compliance (i.e., faking).