Personality, hypnotic susceptibility and EEG responses: Preliminary study

22 men and women, students in psychology, were given the Eysenck Personality Questionnaire, also percent theta, alpha and beta EEG spectral powers were evaluated during an hypnotic induction induced according to Barber's method. The EEG performance was compared with two baseline eyes-open, eyes-closed conditions and with a neutral control situation of listening to a weather report. No relation was found between Extraversion-Introversion scores and scores on the Barber Suggestibility Scale. The difference in EEG powers was nonsignificant for groups high and low in suggestibility, while a significant interaction was found for eyes open or closed × suggestibility groups when extreme scores of Extraversion-Introversion and Neuroticism were considered according to Eysenck's (1966) method. The right theta power of the stable extraverts and neurotic introverts, high in susceptibility in eyes-open condition was higher than the neurotic extraverts, and stable introverts who were low in susceptibility to hypnosis. The right theta power of the neurotic extraverts and stable introverts who were low in susceptibility to hypnosis showed a tendency to increase in eyes-closed conditions, while an opposite observation was made for the stable extraverts and neurotic introverts, subjects who were high in susceptibility. It is interesting to notice, according to Galbraith, et al. (1970) that it was the eyes-open condition which yielded the best EEG predictor of hypnotic susceptibility.