Positive Health Online

Abstract

WILLIAMS and GRUZELIER, Imperial College of Science Technology and Medicine, London, UK and Psychology Group, School of Health and Social Sciences, Coventry University, Coventry, CV1 5FB, UK, john.williams@coventry.ac.uk, investigated the associations of alpha and theta brain activity with relaxation, hypnosis and hypnotic susceptibility in subjects of high and low hypnotic susceptibility.

Background

Methodology

The researchers measured narrow-band theta and alpha activity over anterior and posterior [brain] sites before, during and after hypnosis in 16 adult subjects who had previously been identified as having either high or low hypnotic susceptibility . Experimental measures included electroencephalography (EEG), electrooculography and questionnaires.

Results

'High susceptibles' had greater theta activity post-hypnosis ; otherwise, there were no differences in theta activity between 'high' and 'low susceptibles'. The results from 'highs' and 'lows' suggested that theta activity is an index of relaxation that continues after hypnosis in 'highs'. In 'high susceptibles', alpha activity in posterior sites increased from pre-hypnosis to hypnosis conditions and decreased post-hypnosis . Exactly the converse effects were seen in 'low susceptibles' . 'High susceptibles' showed greater alpha activity than 'low susceptibles' during both pre-hypnosis and hypnosis conditions, indicating an association of alpha activity with hypnotic susceptibility .

Conclusion

The authors state that these results indicate that theta activity indexes relaxation, whereas alpha activity indexes the hypnotic experience and susceptibility .

References

Williams JD, Gruzelier JH. Differentiation of hypnosis and relaxation by analysis of narrow band theta and alpha frequencies. The International Journal of Clinical and Experimental Hypnosis 49 (3): 185-206. Jul 2001.