Binaural beat induced Theta EEG activity and hypnotic susceptibility: Contradictory results and technical considerations

American Journal of Clinical Hypnosis,  Apr 2003  by Stevens, Larry,  Haga, Zach,  Queen, Brandy,  Brady, Brian,  Et al

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The present study offered a constructive replication of an earlier study which demonstrated significant increases in theta EEG activity following theta binaural beat (TBB) entrainment training and significant increases in hypnotic susceptibility. This study improved upon the earlier small-sample, multiple-baseline investigation by employing a larger sample, by utilizing a double-blind, repeated-measures group experimental design, by investigating only low and moderate susceptible participants, and by providing 4 hours of binaural beat training. With these design improvements, results were not supportive of the specific efficacy of the theta binaural beat training employed in this study in either increasing frontal theta EEG activity or in increasing hypnotic susceptibility. Statistical power analyses indicated the theta binaural beat training to be a very low power phenomenon on theta EEG activity. Furthermore, we found no significant relationship between frontal theta power and hypnotizability, although the more hypnotizable participants showed significantly greater increases in hypnotizability than the less hypnotizables. Results are discussed within the context of participant selection and classification factors, technical considerations in the presentation of TBB training, and theta blocking.

Key Words: Activity, binaural beat, brainwave, EEG, hypnosis, hypnotic susceptibility, hypnotizability, theta

In the July 2000 volume of this journal, Brady and Stevens (2000) reported the results of a study designed to test the efficacy of a unique approach to increasing hypnotic susceptibility by driving the brain into states of consciousness reportedly associated with increased susceptibility (Crawford, 1990; Crawford & Gruzelier, 1992). This new technology, called Binuaral Beat Brainwave Entrainment, presented two slightly different waveforms to each ear via stereophonic headphones, with the generation of a third "beat" frequency occurring as the difference between the frequency of the two auditory inputs (Atwater, 1995; Oster, 1973). In this study, this third beat was designed to fall within the theta EEG frequency range (4.0-8.0 Hz), and frontal EEG's recorded during binaural beat exposure revealed significantly increased EEG frequencies within the theta range. Additionally, differences between pre- and post-training Stanford Hypnotic Susceptibility Scale: Form C (SHSS:C; Weitzenhoffer & Hilgard, 1962) scores were statistically significant and only so for low and moderate susceptible individuals (Brady & Stevens, 2000).

Theta EEG brainwave frequencies were selected for change in this original study because of an established relationship between theta (4-8 Hz) wavebands and both hypnotizability and hypnotic trance states (Akpinar, Ulett, & Itil, 1971; Galbraith, London, Leibovitz, Cooper, & Hart, 1970; Tebecis, Provins, Farnbach, & Pentony, 1975). More recently, in technologically more sophisticated and better controlled studies, this theta hypnotizability EEG frequency has been identified as more specific to frontal (DePascalis & Ray, 1998; DePascalis, Ray, Tranquillo, & Amico, 1998; Sabourin, Cutcomb, Crawford & Pribram, 1990) and to frontotemporal (Graffin, Ray & Lundy, 1995) brain regions. In fact, Crawford and Gruzelier (1992) report frontal theta, and perhaps more specifically frontal high theta (5.5-7.5 Hz), EEG frequencies as the most consistent EEG correlate of hypnotic susceptibility. This well-established relationship notwithstanding, no study prior to our earlier investigation had endeavored to directly change frontal theta and to observe a subsequent change in hypnotic susceptibility.

The results of the Brady and Stevens (2000) study were also clinically important for a number of reasons. First, hypnotic susceptibility has been shown to play an important role in the maintenance of health and in the prevention and treatment of disease. For example, significant relationships have been reported in the research literature between hypnotizability and the reduction of chronic pain, headaches, skin disorders, and asthma symptoms (Bowers, 1979, 1982; Brown, 1992) and increased immunocompetence (Ruzyla-Smith, Barabasz, Barabasz, & Warner, 1995). And a recent meta-analysis of psychological treatments employed in research studies to influence immunocompetence revealed hypnotic suggestions to be one of the most consistently effective treatments compared with stress management, relaxation, disclosure, and conditioning interventions, and this effect was most robust for highly hypnotizable participants (Miller & Cohen, 2001). The ability to easily and effortlessly increase hypnotic responsiveness, even modestly, could have a profound impact on a patient's response to therapeutic suggestions and could increase the clinical efficacy of hypnosis with a broader range of patients.

Secondly, increasing hypnotic susceptibility has been a problematic and controversial enterprise for decades, with many practitioners and researchers accepting individual hypnotic responsiveness as a relatively stable, immutable characteristic (Perry, 1977). Nonetheless, a number of experiences have been shown to increase hypnotic susceptibility, including sensory deprivation, biofeedback, psychotomimetic drugs, hypnotic training, personal growth, and natural developmental changes (Bowers, 1976). And some of these changes in hypnotizability have been rather dramatic. For example, Barabasz (1982) was able to demonstrate a 147% increase in susceptibility following 6 hours of sensory restriction, and Gorassini and Spanos (1986) produced not only a 129% increase in objective hypnotizability but similar increases in the subjective components of hypnotic experience following 1 hour of coaching, practice, and modeling of cognitive strategies mediating responsiveness to suggestions, interpretational sets, and attitudes toward hypnosis.1