Attention-related electroencephalographic and event-related potential predictors of responsiveness to suggested posthypnotic amnesia.

Higher frequency electroencephalographic (EEG) activity around 40 Hz has been shown to play a role in cognitive functions such as attention. Furthermore, event-related brain potential (ERP) components such as N1 and P1 are sensitive to selective attention. In the present study, 40-Hz EEG measures and early ERP components were employed to relate selective attention to hypnotic response. Participants were 20 low hypnotizable individuals, half assigned as simulators, and 21 high hypnotizable individuals. Each of these groups was subsequently divided into two groups based on recognition amnesia scores. The four groups differed in 40-Hz (36-44 Hz) EEG spectral amplitude recorded during preinduction resting conditions but not in EEG amplitude postinduction. The groups also differed in N1 amplitudes recorded during hypnosis. Regression analysis revealed that these effects only distinguish the high hypnotizable participants who experienced recognition amnesia from all other groups. The findings support the role of selective attention in hypnotic responsiveness, and the utility of subdividing high hypnotizable individuals is discussed.