Binaural-beat induced theta EEG activity and hypnotic susceptibility.

Six participants varying in degree of hypnotizability (2 lows, 2 mediums, and 2 highs) were exposed to 3 20-minute sessions of a binaural-beat sound stimulation protocol designed to enhance theta brainwave activity. The Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) was used for pre- and post-stimulus measures of hypnotic susceptibility. A time-series analysis was utilized to evaluate anterior theta activity in response to binaural-beat sound stimulation over baseline and stimulus sessions. The protocol designed to increase anterior theta activity resulted in a significant increase in percent theta for 5 of 6 participants. Hypnotic susceptibility levels remained stable in the high-susceptible group and increased significantly in the low and medium-susceptible groups.