EEG CONCOMITANTS OF HYPNOTIC-SUSCEPTIBILITY

Numerous historical attempts have been directed at understanding elect rocortical concomitants of hypnosis. Today, with the availability of m ore sophisticated multichannel recording technologies and signal-proce ssing approaches, it is possible to reconsider and update previous att empts. The most solid relationship between electrocortical activity an d hypnotizability exists in the EEG theta frequency range. Given the s table electrocortical differences found in high and low susceptible in dividuals, the question arises whether we can use additional EEG measu res to help understand the nature of these individual differences. One possible alternative is the pointwise or fractal dimension, which we examined during baseline conditions with high and low hypnotic suscept ible individuals. The dimensionality measures suggest that high suscep tible individuals display underlying brain patterns associated with im agery, whereas low susceptible individuals show patterns consistent wi th cognitive activity (i.e., mental math). This type of speculation is similar to that of Tellegen, who makes a distinction between imaginat ive versus realistic responding. Future research should address the ex act nature of the underlying process (imagination, effortlessness, sug gestibility, etc.) seen in high and low susceptible individuals.