A number of clinical and laboratory studies point to a shift in involvement of the two cerebral hemispheres in dreaming, hallucinogen administration, transcendental meditation, and sexual orgasm — such that the hemisphere not dominant for speech becomes temporarily the preponderant one. Usually this is the right hemisphere (in right-handed and in many left-handed subjects). The authors have completed a study suggesting that the various altered states of awareness we subsume under the heading of hypnosis also are accompanied by a shift toward greater participation by the right brain.

The authors measured cerebral hemisphere dominance before, during and after hypnotic suggestion. During hypnosis, their subjects showed lower right ear/left hemisphere laterality scores (on a dichotic listening task) compared to the control periods. These results are compatible with the hypothesis that hypnotic and other “unconscious” phenomena are manifestations of temporary shifts in cerebral dominance, in which the “nondominant” hemisphere plays the major role.