Psychophysiological correlates of hypnosis and hypnotic susceptibility

This article reviews and summarizes electroencephalographic (EEG)-based research on physiological and cognitive indicators of hypnotic responding and hypnotic susceptibility, with special attention to the author's programmatic research in this area. Evidence that differences in attention levels may account for hypnotic depth and individual differences in hypnotizability is provided with traditional EEG rhythms, event-related potentials, and 40-Hz EEG activity. The alteration of stimulus perception may be a secondary effect with respect to allocation of attentional resources. In both nonhypnosis and hypnosis conditions, high hypnotizables appeared to show greater task-related EEG hemispheric shifts than did low hypnotizables. Findings concerning cognitive and physiological correlates of hypnotic analgesia are discussed with respect to hemispheric functioning in the apparent control of focused and sustained attention. The conclusion is that although a definitive EEG-based signature for hypnosis and hypnotizability is not yet established, there are a number of promising leads.