Electrophysiological alterations during hypnosis for ego-enhancement: a preliminary investigation

EEG activity at the midfrontal (Fz) region was recorded during pre- and postbaselines, live hypnotic induction, arm levitation and progressive relaxation (PNR) deepening, and therapeutic ego-enhancing suggestions among 60 college student volunteers, previously screened with the Stanford Hypnotic Susceptibility Scale, Form C. Comparisons across conditions for delta, theta, alpha, and beta activity were made between low, moderate, high, and very high hypnotizable groups. Results indicated (a) significant increases in theta EEGs across the hypnosis process with a peak at PNR and a drop in theta thereafter to termination, with highs showing significantly more dramatic effects than moderates; (b) a similar inverted U-shaped pattern for beta EEGs across hypnosis conditions, with very highs significantly higher in beta power than moderates and lows, and with highs significantly higher than moderates; (c) general profile differences between the highs for theta and the highs and very highs for beta in comparison to the moderates and lows, with peak theta and beta power occurring during ego-enhancing suggestions for more highly hypnotizable participants; (d) a drop in alpha EEGs across the trance process with a return to baseline after hypnosis, with moderates showing significantly lower alpha power; and (e) an increase in delta power across conditions to PNR and then a decrease to post-hypnosis baseline, with moderates significantly lower than highs.