EEG CONCOMITANTS OF HYPNOSIS AND HYPNOTIC-SUSCEPTIBILITY

Electroencephalograph (EEG) measures described high- and low-hypnotiza ble participants in terms of 3 conditions: an initial baseline period; baselines preceding and following a standard hypnotic induction; and during the induction. The following results were obtained. 1. High and low-hypnotic susceptible participants displayed a differential patter n of EEG activity during the baseline period, characterized by greater theta power in the more frontal areas of the cortex for the high-susc eptible participants. 2. In the period preceding and following a stand ardized hypnotic induction, low-susceptible participants displayed an increase in theta activity, whereas high-susceptible participants disp layed a decrease. 3. During the actual hypnotic induction itself, thet a power significantly increased for both groups in the more posterior areas of the cortex, whereas alpha activity increased across all sites . Implications of these data include the possibility of psychophysiolo gical measures offering a stable marker for hypnotizability, and anter ior/posterior cortical differences being more important than hemispher ic foci for understanding hypnotic processes.