Hypnosis as distinct from Suggestion

Current theoretical frameworks appear to be moving toward an even clearer distinction than we had in the past between the hypnotic induction process and the resulting condition of hypersuggestibility. Most classical hypnotic induction is indistinguishable from other means of helping to induce a relaxed condition in the body. Also, a number of experiments have demonstrated enhanced suggestibility under conditions where the body is not relaxed (suggestion works outside of hypnosis).

The common link between most situations of hypersuggestibility appears to be a narrow selective focus of attention. This is something which seems to result from such diverse conditions as sensory isolation, relaxed attentiveness, and extreme fear. There does not appear to be a single common general EEG pattern in hypersuggestibility, or which makes hypnotized individuals distinguishable from awake ones, though there are hints of possibly unique evoked potential responses during periods of enhanced suggestibility.

One of the more intriguing recent theories is that hypersuggestibility may somehow also be mediated by the immune system and other chemically linked autonomic systems rather than the brain alone. A two-way chemical feedback loop has been discovered to operate between the nervous and immune systems, but it will take further research to determine its relationship to suggestibility and psychosomatic illness and healing in general.

What is the neurobiological basis of suggestibility and of dissociation?

Traditional cortical inhibition theories hold that hypersuggestibility is the result of inhibition of the cerebral cortex (and thus the usual 'critical faculties') due to some sort of override by lower brain centers. This has proven to be an overly simplistic way of looking at it. A more recent version of that former Pavlovian theory is that the left cerebral hemisphere is somehow selectively inhibited during conditions of hypersuggesibility.

This is an expression of the popular culture view of 'left-brained' and 'right-brained.' As for most behavior, there will likely be evidence for a differential contribution from the asymmetric cerebral hemispheres in hypersuggestibility, but so far differential hemisphere activity itself does not seem to be the primary mechanism of enhanced suggestibility.

We have good reason at this point to think of enhanced suggestibility as a common endpoint toward which a number of methods can lead in some or all human beings. Hypnotic induction is only one of these methods. There are also very good indications that there is something special about some forms of dissociation that merits further investigation into just what cognitive functions become split, under what conditions these splits occur, and how they occur. It is also of great interest how dissociation relates to various anomalous phenomena (such as extrasensory perception, psychokinesis, and others) that have long been associated with 'dissociative states.'