Very hypnotizable individuals commonly report a variety of anomalous experiences after a hypnotic induction, however, there has been no previous research on the neurophenomenology of spontaneous hypnotic experiences, which this research focused on.
We used a stratified sample (N = 40) of high, medium, and low hypnotizable participants. In session 1, cortical activity was measured using qEEG during an eyes-closed sitting-quietly period and while voluntarily lifting an arm prior to and following a hypnotic induction. In session 2, participants’ spontaneous mentation was obtained in reference to a baseline period and multiple prompts following a hypnotic induction, which consisted of the suggestion for participants to go into their “deepest” state. Participants also completed the Phenomenology of Consciousness Inventory (PCI) for baseline and hypnosis periods, and gave reports of hypnotic depth for different periods.
There were main effects of hypnotizability, condition (baseline and hypnosis) and an interaction between
them. Although the groups did not exhibit different hypnotic depth reports at baseline, hypnotic depth was found to increase in medium and high hypnotizables during hypnosis. With regard to the PCI, hypnotizability was related to having an altered experience, and various other alterations. Participants’ deepest hypnotic state, relative to baseline, was also associated with altered experience and various other alterations, and there was a significant interaction between these variables. Alterations in consciousness were more common in medium and high hypnotizables than lows, especially after hypnosis. Verbal reports were content analyzed according to experiential categories. The experience of low hypnotizables was characterized by “normal” mentation, that of medium hypnotizables was centered more on vestibular and similar sensations, and that of high hypnotizables contained imagery, positive affect and mystical-like phenomena. Spectral and source localization EEG analyses corroborated various patterns of differential brain functioning across levels of hypnotizability and during different conditions. Among the most salient findings were a positive correlation between a global measure of brain functioning complexity (omega complexity) and hypnotizability, and a positive correlation between omega complexity and 2 types of experiences: positive affect/mystical-like phenomena, and imagery. The induction of hypnosis had different effects on low and high hypnotizables: whereas frontal cortical activity increased from baseline to hypnosis in the former, it decreased in the latter.
Results suggest that a hypnotic procedure can effect significant alterations in consciousness, and it show a clear correspondence between phenomenological reports and EEG activity.
Cardeña, E., Lehmann, D., Jönsson, P, Terhune, D., & Farber, P. (2007). The neurophenomenology of hypnosis. Proceedings of the 50th Annual Conventions of the Parapsychological Association, 17-30. Cardeña, E., Kallio, S., Terhune, D., Buratti, S., & Lööf, A. (2007). The effect of translation and sex on hypnotizability testing. Contemporary Hypnosis, http://www3.interscience.wiley.com/cgi-bin/fulltext/116840768/PDFSTART. Cardeña, E., Terhune, D., Lööf, A., & Buratti, S. (in press). Hypnotic experience is related to emotional contagion. International Journal of Clinical and Experimental Hypnosis.