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Dr.Jose Luis Hernani Ph.D.

Clinical Psychopedagogist, Psychotherapist and Hypnotherapist.

Founder and President of the Peruvian Association of Clinical and Experimental Hypnosis (1995-2014).


Certified and Approved International Instructor of Hypnotherapy by the American Board of Hypnotherapy (USA).      www.hypnosis.com


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We provide personal and online Psychotherapy and Hypnotherapy services.

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What is a hypnotic 'trance'?

'Trance;' descriptive or misleading?

Most of the classical notions of hypnosis have long held that hypnosis was special in some way from other types of interpersonal communication and that an induction (preparatory process considered by some to be neccessary in the production of hypnotic phenomena) would lead to a state in which the subject's awareness and behavioral responding was somehow altered from the usual.

The name historically most commonly associated with this altered state of functioning is 'trance,' a term shared by the description of the activities of certain spiritualist mediums and other phenomena that some psychologists might refer to as 'dissociative,' because something about the individual's personality appears split off from the usual response patterns to the environment.

Trance, for reasons we shall examine here, can be a very misleading term for what is going on in hypnosis, since it is not neccessarily a sleep or stupor as some of traditional connotations of the term trance imply.

But 'trance' is so ubiquitous in literature that it might serve us to be familiar with its uses and the issues underlying it, and to use it as a starting point.

There were a great many experimental and clinical studies done to try to determine what might be unique about hypnosis, as opposed to other kinds of situations (e.g. people simply being motivated to comply with the hypnotist; i.e. hypnotic simulators). Outward behavioral signs and virtually every physiological measurement reported in hypnosis differ seemingly not at all from the usual waking state of consciousness, as the non-state theorists contend.

Years of careful analysis by a number of researchers were mostly fruitless in turning up any reliable physiological correlates of hypnosis that were not (1) related to the relaxation associated with the induction (most inductions, but not all, involve physical relaxation); or (2) an obvious result of a suggestion rather than the mechanism responsible for the observed suggestibility assumed to some degree unique to hypnotic trance.

At least one theory of hypnosis considers it equivalent to a form of relaxation. Comparison of various relaxation methods with regard to both objective measurements and subjective reports indicate deep relaxation accompanying some hypnosis but not all hypnosis. Hypnotic suggestibility is apparently not limited to relaxed states.

In Morse, Martin, Furst, & Dubin, "A physiological and subjective evaluation of meditation, hypnosis, and relaxation," from Journal Psychosomatic Medicine. 39(5):304-24, 1977 Sep-Oct, a representative study of relaxation was done.

Subjects were monitored for respiratory rate, pulse rate, blood pressure, skin resistance, EEG activity, and muscle activity. They were monitored during the alert state, meditation (TM or simple word type), hypnosis (relaxation and task types), and relaxation. Ss gave a verbal comparative evaluation of each state. The results showed significantly better relaxation responses for the relaxation states (relaxation, relaxation- hypnosis, meditation) than for the alert state. There were no significant differences between the relaxation states except for the measure "muscle activity" in which meditation was significantly better than the other relaxation states. Overall, there were significant differences between task-hypnosis and relaxation-hypnosis. No significant differences were found between TM and simple word meditation. For the subjective measures, relaxation-hypnosis and meditation were significantly better than relaxation, but no significant differences were found between meditation and relaxation-hypnosis.

There are a few more recent attempts to find physiological correlates of hypnotic suggestibility. One of these was EEG research by David Spiegel of Stanford, published in the Journal of Abnormal Psychology, 94:249-255, by Spiegel, Cutcomb, Ren, and Pribram, (1985) "Hypnotic Hallucination Alters Evoked Potentials." Spiegel seemed to find an evoked response pattern that appeared during hypnotically suggested hallucination yet not during simulation of hypnotic hallucination. Nicholas Spanos and others have argued that this EEG data has been misinterpreted given the nature of the control subjects used. (Author's response to commentary by Spiegel, of Spanos, N. (1986) "Hypnotic Behavior: A Social-Psychological Interpretation of Amnesia, Analgesia, and 'Trance Logic'." Behavioral and Brain Sciences 9:449-502).

In another similar attempt, from 1976, but measuring certain frequencies of EEG activity rather than evoked potentials, a Russian journal reports some tentative success at finding a physiological correlate to hypnotic induction. See Aladzhalova, Rozhnov, & Kamenetskii, "Human hypnosis and super-slow electrical activity of the brain." [RUSSIAN] Zhurnal Nevropatologii I Psikhiatrii Imeni S - S - Korsakova. 76(5):704- 9, 1976.

In the above article, the authors studied the transformation of infraslow oscillations of brain potentials in 15 patients with neuroses during 50 sessions of hypnosis. The results of such studies permitted to distinguish some important traits in the changes of infraslow oscillations of brain potentials in different stages of hypnosis. It is concluded that a study of these changes during hypnosis may establish some correlations between the physiological state of the brain and the unconscious mental processes.

Are there potential clues in 'trance logic?'

One particular researcher, psychiatrist M.T. Orne of the University of Pennsylvania, finally concluded that objective correlates were not to be found in the available physiological measurements of the time, and that they were apparently of no value in determining whether a hypnotized subject was 'truly hypnotized' or 'simulating hypnosis.'

Orne, who did recognize from both highly consistent verbal reports of hypnotized subjects and from various clinical and empirical studies that there was indeed something unique about hypnosis in at least some subjects, concluded that that he would have to use verbal reports of subjective experience rather than rely on measurements. He carried out a series of clever experiments which seemed to establish a reliable way of distinguishing simulators from hypnotized subjects by their verbal reports. The resulting alteration of mental function was found to be present in nearly all deeply hypnotized subjects, and almost never found to the same degree in people who were not hypnotized but were motivated to simulate hypnotic phenomena.

The most obvious aspects of this alteration of function were dubbed 'trance logic,' and appeared to correlate well with the anecdotal reports of the clinicians like Milton Erickson who had long considered verbal reports of hypnotized subjects to be valuable in distinguishing what was going on in hypnosis.

What is Trance Logic?

Trance logic refers to a set of characteristics of mental functioning that are specifically found in 'deep trance' phenomena of hypnosis, as opposed to 'light trance,' which has not even reliable subjective correlates and cannot really be distinguished from simulation experimentally. These characteristics involve particularly an alteration in language processing. Words, in trance logic, are interpreted much more literally, communication being conveyed by focusing on words themselves rather than ideas. There is also an associated decrease in critical judgement of language being processed, and an increased tolerance for incongruity.

It is in some ways as if the subject were like a small child with very limited experience to use in interpreting ideas conveyed by the hypnotist. There also is a shift toward what psychoanalysts call 'primary process' thinking, or thinking in terms of images and symbols more than words; an increased availability of affect; and other characteristics that simulators do not consistently reproduce.

This consistent set of characteristics of deep trance has been one of the influences leading to several kinds of theories of what trance actually involves:

  1. Partly because language skills are 'child-like,' and meaningful long forgotten childhood memories can apparently sometimes be vividly re-experienced (see the later section on the reliability of recall in hypnosis) the theory that trance generally represents some kind of psychological regression to an earlier developmental stage has long been popular in some circles.
  2. Partly because the individual appears to become disconnected somehow with the usual context they use to evaluate ideas, a cognitive dissociation theory arose. (Also partly because of anomalies involving apparent multiple simultaneous 'intentions.')
  3. Partly because the cues prompting the subject's behavior become more internal and progressively more obscure to an outside observer, trance has been viewed as 'contact with the unconscious mind.'
  4. Largely because some of the characteristics of trance logic correlate well with some of those discovered to be specialized in many people in the non-dominant cerebral hemisphere, there is also a popular theory that deep trance involves a somehow selective use of one hemisphere of the brain, or in the most simplified version of this theory, a 'putting to sleep' somehow of the dominant (language specialized) hemisphere. Some brain scientists strongly disagree with this view, emphasizing the complex interdependence of the brain hemispheres even in typical hypnotic-type situations.

Critique of Trance Logic

The notion of trance logic, rooted as it is in subjective reports, has been questioned by some of the non-state theorists, such as Nicholas Spanos, who do not believe that trance logic represents any sort of defining characteristic of hypnotic responding.

Examples of critiques of this concept can be found in Nicholas Spanos, "Hypnotic behavior: A social-psychological interpretation of amnesia, analgesia, and 'trance logic,'" Behavioral and Brain Sciences 9(1986):449-502, and a paper cited by Spanos in the above; Nicholas P. Spanos, H.P. de Groot, D.K. Tiller, J.R. Weekes, and L.D. Bertrand, "'Trance logic' duality and hidden observer responding in hypnotic, imagination control, and simulating subjects," Journal of Abnormal Psychology 94(1985):611-623.

Trance as distinct from sleep or stupor

I think we can fairly conclude from the research on hypnosis done so far that 'trance' may in fact have useful meaning for describing the subjective experience of subjects in hypnotic situations, but is not explained, or even described, by any one simple theory yet proposed, either neurological or psychological. All of the current theories seem to leave aspects unexplained.

Clearly, selective cerebral inhibition and activation of some kind is involved at various stages of a hypnotic induction, but not yet in any way we can uniquely distinguish from other forms of waking response to changing stimulii in other situations. And certainly hypnotic response does not rely upon the generallized inhibition found in the action of depressant drugs or in the normal sleep state. It is a much more highly specific effect, if indeed it truly is distinct in some way, as subjective data appear to suggest.

The most common neurological theories of hypnosis over the years as a form of partial sleep have mostly been based on (1) the superficial resemblance of a classically induced subject to a near-sleeping person, (2) on the ease with which a deeply hypnotized subject will fall off to sleep on suggestion or if hypnosis is not explicitly ended, and (3) because various drugs that induce sleep-like or stuporous states can produce some of the same characteristics as hypnotic trance.

It has been very consistently determined that trance itself has nothing at all to do with sleep, and is much more easily distinguished from a sleeping state physiologically than from a waking state. Measurements attempted included a number of famous early experimental studies in the 1930's, on such variables as EEG measurements, cerebral circulation, heart rate, respiration, basal metabolism, and various behavioral parameters. Representative of these experiments comparing hypnosis and sleep was: M.J. Bass, "Differentiation of the hypnotic trance from normal sleep," Journal of Experimental Psychology, 1931, 14:382-399.

Though the mentation in hypnosis often resembles dreaming, it appears much closer to daydreaming in character than to normal night time dreaming.

Clark Hull, in his 1936 classic Hypnosis and Sugestibility describes a number of experimental setups for distinguishing the mental characteristics of sleep from those of hypnotic trance.

One thing suggested by this is that if sleep can be viewed as largely a generallized cortical inhibition, and trance is not in any determinable way identified with sleep, that trance is not a form of sleep or a stupor. This is also easily determined by observing the range of activities possible in hypnotized subjects (compared to waking subjects and those under the influence of depressant drugs).

'Trance Reflex' and the appearance of stupor

So the question remains, if trance is not sleep or stupor, then why do hypnotized subjects commonly appear so passive?

The consensus on this subject, from studies of 'waking hypnosis,' ('trance' in which the subject acts normally and does not show any evidence of the classical relaxed deep trance state), and from many years of clinical observations, is that the apparent lethargy and catalepsy are more a result of suggestions used to deepen hypnosis than a neccessary correlate of suggestibility or trance itself in general. In a way, a side-effect of trance rather than a quality or cause of trance. There is also seemingly a temporary but distinct immobilizing reflex following certain kinds of stimuli used in some hypnotic inductions. This may help provide a temporary or initial facilitation of hypnotic suggestibility in some people, according to some theories.

Monotonous visual stimuli, surprise, fear, physical restraint, and a number of other factors have long been observed to produce 'trance' with fixation (followed by defocusing) of gaze, narrowing or attenuation of externally focused attention, general immobility, and various physiological changes which resemble the correlates of relaxation and internally directed (visual) attention in humans.

Perhaps the most routine observance of this is with people gazing into television sets or in the familiar case of 'highway hypnosis.' It appears that this type of 'trance' induction often precedes the production of hypnotic suggestion phenomena, and can occur prior to any verbal suggestions, from proprioceptive or visual stimuli alone. It is probably closest to the traditional view of the hypnotist swinging a watch to put their subjects 'to sleep.'

One means of searching for the basis for this seemingly reflexive trance response is from phylogenetic data, using animals. A similar response occurs in monkeys and other animals under both laboratory and natural conditions, as an apparent passive defensive response (resembling death) under certain extreme conditions.

Various Russian researchers investigating animal hypnosis seem to have discovered electroencephalographic correlates of this animal 'death trance' which resembles the initial trance/inhibition effect that sometimes precedes human hypnotic suggestibility. They report an interhemispheric asymmetry of the brain, which a recent Russian email journal article, (Petrova E.V., Shlyk G.G., Kuznetsova G.D., Shirvinska M.A., Pirozhenko A.V., HYPNOSIS IN MACACA RHESUS IS CHARACTERIZED BY DIFFERENT PHASES AND INTERHEMISPHERIC EEG ASYMMETRY), summarizes as being

"created as the result of the activation of the right hemisphere."


They cite:


  • Simonov P.V. The Motivation Brain, Gordon a. Breach Pub., N.Y.-L., 1992.
  • Kuznetsova G.D., Nezlina N. I., Petrova E.V. Dokl. Akad. Nauk, 1988, 302:623.
  • Petrova E.V., Luchkova T.I.,Kuznetsova G.D. Zh. Vyssh. Nerv. Deyat. 1992, 42: 129.

As evidence of a correlation between right hemisphere cortical activity and human hypnosis, they cite:

  • Gruzeiler J., Brow T., Perry A. et al. Int. J. Psychophysiol., 1984, 2:131.
  • Meszaros J., Growford H.J., Nady-Kovacs A, Szabo Cs., Neuroscience, 1987, Suppl. 22:472.

One investigation into the relationship of primate behavior and electrical activity of the brain (EEG) involved 45 male Macaca Rhesus monkeys seated in a primatologic chair and observing the oscillation of a shining ball, 4 cm in diameter, placed 15 cm in front the animal's eyes for 15-20 minutes.

In this experiment, six of the monkeys immediately stopped motor activity. At first their eyes were fixed on the ball, then muscle tonus weakened, eyes became unfocused, and respiration slowed. These same symptoms appeared in the remaining animals, although they developed slower. During the first 2-3 minutes of the stimulation, the slower responding monkeys showed a negative reaction to the ball (a monkey abruptly turned away or tried to push it away). Then the negativism ceased and the first signs of inhibition appeared: yawning, scratching, and obtrusive hand motions.

Finally, what the experimenters call the 'hypnotic state' ensued; eyes fixed on the ball, the animal became calm, and closed its eyes. This state continued from several seconds to several minutes and could be observed several times during an experimental session. In 12 monkeys that displayed orienting or aggressive response to the ball, visual signs of inhibition were not observed under these conditions. Further physical restraint (fixation of hands and trunk) resulted in the 'hypnotized' behavior. This is in contrast to the more usual behavior of monkeys, what the authors of the article call the 'freedom reflex' which results when they are taken from their home cages and placed in the primatologic chair.

As they describe the EEG observations:

"The electrical activity of monkey brain cortex before hypnosis was characterized by a robust polyrhythmia and presence of theta- and beta-rhythms. In one monkey the alpha-rhythm was dominate. During hypnosis, slow activity (delta and theta) with increased amplitude appeared, periodically alternating with low-amplitude activity. Power spectrum maps showed that in the low-amplitude phase the decrease in the power of all rhythms was paralleled in three monkeys with robust beta-1 rhythm with a predominance in the left hemisphere. In the high-amplitude phase, delta and theta-rhythms dominated in the right hemisphere."

"The analysis of the coherence and correlation functions showed the decreased relationship between hemispheres (especially in the frontal cortical areas) under hypnosis and its increase during relaxation (as compared to the background)."

"The analysis of the EEG showed that in the brain of hypnotized monkeys interhemispheric asymmetry appears: the domination of the theta- and delta-rhythms in the right hemisphere or beta-rhythm in the left hemisphere - depending upon the phase of hypnosis."

Factors shown to facilitate this "animal hypnosis" include vestibular (pose in the chair) and somatosensory (fixation) stimuli and emotional stress (fear), novelty to the experimental conditions, and additional proprioceptive (restriction of the motor freedom) and visual influences. Various sources seem to indicate similar factors which operate on the corresponding 'trance response' in humans.

In addition to the 'trance reflex' which is seen to sometimes accompany or precede hypnotic induction, the factor of 'trance logic' which surfaces under deep trance also adds to the catatonic appearance, as the primitive language capacity in trance logic could easily contribute to the appearance of stupor. But the individual is actually, in general, wide awake and thinking, and in control of themself, but extraordinarily focused on their internal experience, and on the voice of the hypnotist.

"... the general tendency of the hypnotic subject to be passive and receptive is simply expressive of the suggestibility of the hypnotic subject and hence a direct result of the suggestions employed to induce hypnosis and not a function of the hypnotic state."

Milton Erickson, circa 1944.

The most obvious reason to make this distinction is to dispell the popular myth that a hypnotized person is unconscious or unable to respond to emergencies, or to oppose the will of the hypnotist if they should wish to do so. In fact, Erickson did a famous detailed study of attempts by the hypnotist to force their will on hypnotized subjects, and observed that not only did the subjects discriminate what suggestions they would and would not respond to, and refused to respond to some, but then often came up with ways to hurt or humiliate the hypnotist in retaliation for the attempt. And that they were even more selective about what suggestions they would not respond to under hypnosis than they were normally!

Another reason this distinction is made is because of extraordinary skills of some hypnotists to 'induce trance' (gain a unique kind of compliance or communication) with people who had not been prepared or relaxed by a classical induction, and who in fact steadfastly and effectively resisted all attempts at classical induction of trance.

A third reason is that we observe in some hypnotic phenomena that an individual can be hypnotized, with the help of a traditional progressive relaxation procedure for example, and then "remain hypnotized" (equally responsive to suggestion) long after leaving the state of physiological relaxation and classic apparent catatonia. So, the 'trance,' though it may in fact start with a process similar to that which commonly leads to sleep, or may start with the 'trance reflex,' it is not dependent upon stupor, nor even neccessarily relaxation.

Evidence of enhanced functioning following suggestion?

Some of the 'unusual capacities' often claimed of hypnosis are actually legitimate, but found to be quite normal capacities seen in various non-hypnotic situations as well, though the hypnotic 'deep trance' context does apparently give a unique kind of access to those normal capacities. Seemingly a product of the unique sort of attention control found in hypnotic responding.


"Trance permits the operator to evoke in a controlled manner the same mental mechanisms that are operative spontaneously in everyday life."

Milton Erickson

T.X. Barber, a highly respected researcher into human functioning under hypnosis has long promoted the view that people can bring out their own inner capabilities by direct requests to think, feel, and experience in a suggested way, without any need for hypnotic induction. He says that the secret of hypnosis involves the ability to fantasize in a hallucinatory way and provide the drama and excitement. Also important, according to Barber, is the way in which suggestions are given, language which gives firm but metaphorical suggestions.

Keith Harary, in his March/April 1992 Psychology Today article, "The trouble with HYPNOSIS. Whose power is it, anyway?" reviews a number of critical studies of hypnosis and concludes a a similar view:

"Packaging them [the true claims made about hypnosis] under the label 'hypnosis' conceals what is really going on. It doesn't even begin to suggest that they are our very own powers and there might be ways to get at them directly and entirely on our own."


'Mind and Body' in medicine

We see that there is little of any consistency that can be said about light trance objectively, and possibly only 'trance logic' (if that) as a common characteristic of deep trance. Yet the subjective experience of the individual is sometimes very profoundly altered.

And some phenomena can be reliably reproduced in good subjects which are medically considered very unusual and hard to explain (though not neccessarily limited to hypnosis situations). The working medical framework that had traditionally cleanly separated psychogenic from physiological effects has been revised in parts to allow for some of the mechanisms related to effects found in good hypnotic subjects; such as influences between neural and immunological systems, dermatological (skin) responses that were previously believed not to be able to be influenced by the brain and nervous system, and the difficult but demonstrable 'biofeedback' ability to indirectly control very small neural units previously considered completely autonomic.

In terms of the prevailing medical paradigm, numerous functional interconnections within the brain and between the nervous system and other body systems have been found that may gradually help to explain such remarkable effects as we see in hypnosis and under various other seemingly special psychological conditions. Among other key discoveries, the study of neuropeptides and their distribution throughout the body as well as the brain provides some potential answers for some of the more perplexing questions arising from effects due to suggestion.

Richard Benson's "relaxation response" research pioneered in this area, and a great many studies since then have validated his ideas about psychological and physiological functions greatly influencing each other. Two recent article that are fairly typical are in the June 1989 issue of the mainstream medical specialty journal Gastroenterology, "Hypnosis and the relaxation response" and "Modulation of gastric acid secretion by hypnosis."

An excellent review of the research into the exact physiological effects found to result from hypnotic suggestions in particular may be found in these two of T.X. Barber's articles ...

  • "Physiological effects of 'hypnosis,' Psychological Bulletin, 58: 390-419, 1961.
  • "Physiological effects of 'hypnotic suggestions': a critical review of recent research (1960-1964)," Psychological Bulletin, 63: 201-222, 1965.

In addition to these general references, the following sections may help to followup on any interest into various specific apparent unusual effects of suggestion.

Hypermnesia, perceptual distortions, hallucinations

Hypermnesia is perceived enhanced recall of memories. See also the later section on the reliability of hypnotic recall.

An excellent overview of experimental and clinical studies of hypermnesia, perceptual distortions, and hallucinations under hypnosis may be found in the hypnosis section of the Annual Review of Psychology, especially these issues spanning 20 years of research into hypnotic phenomena:

  • Vol 16, 1965, E. Hilgard, p. 157-180
  • Vol 26, 1975, E. Hilgard, p. 19-44
  • Vol 36, 1985, J.R. Kihlstrom, p. 385-418

Another related area is the remarkable phenomena of eidetic imagery, or 'photographic memory.' In recent years, this formerly controversial phenomenon has been demonstrated by means of computer generated random pixel patterns which stereoscopically encode a visual image. There would be two images which, one seen by each eye at the same time, produce a three dimensional visual image. It is considered virtually impossible to detect the encoded image by looking at the separate encoded patterns at different times. People with eidetic imagery can memorize one pattern, and then mentally project it with one eye while looking at the other pattern with the other eye. The result is that they can see the three dimensional image, while apparently no amount of motivation will permit someone without eidetic imagery to see the final image.

It is now known that many five year old children can experience eidetic imagery, and that it is very rare in adults. A study published in the Journal of Abnormal Psychology in 1975 (and a followup three years later) demonstrated that the rate of eidetic imagery in adults hypnotically regressed to age five was comparable to that in actual five year olds.

This could be interpreted as evidence of true temporal regression in hypnosis in some sense, although that interpretation seems unlikely in the face of evidence in other areas. It is more likely to provide unique evidence of state-specific abilities accessible through hypnotic suggestion.

The following are the studies quoted above:

  • Walker, Garrett, & Wallace, 1976, "Restoration of Eidetic Imagery via Hypnotic Age Regression: A Preliminary Report," Journal of Abnormal Psychology, 85, 335-337.
  • Wallace, 1978, "Restoration of Eidetic Imagery via Hypnotic Age Regression: More Evidence," Journal of Abnormal Psychology, 87, 673-675.

In addition, Michael Nash in his chapter "Hypnosis as Psychological Regression," in Lynn and Rhue's 1991 Theories of Hypnosis discusses the evidence around different kinds of psychological regrression and also refers to an unpublished manuscript by Crawford, Wallace, Katsuhiko, and Slater, from 1985, which is said to also discuss positive evidence for the faciitation of eidetic imagery phenomenon with hypnotic techniques: "Eidetic Images in Hypnosis, Rare but There."

Posthypnotic suggestion and amnesia

Amnesia (basically selective forgetting in this case) sometimes occurs spontaneously in hypnosis, and sometimes happens as the result of a direct or indirect suggestion to forget something. The amnesia effect may last a variable time, possibly months or longer, depending on the psychological significance of the amnesia and the forgotten material and on the intensity of attempts to recall and availability of recall cues in the environment.

A posthypnotic suggestion in general is a response to hypnotic suggestion that extends beyond the boundary of the actual trance period. Posthypnotic suggestions are often performed without any knowledge that they were previously suggested (thus the neccessary link to hypnotic amnesia of this phenomena). The individual responding to a posthypnotic suggestion and with amnesia for the source of the suggestion will generally incorporate the response into their ongoing activities without disruption, in a similar manner to rituallized actions that we pay little attention to such as brushing our teeth in the morning or making the right sequence of turns in our well established route to work each morning. If the response involves some bizarre action, the individual will either be confused or typically will come up with a creative rationalization for the behavior. Very rarely will there be any awareness of the action resulting from a previous suggestion.

It is the contention of many experts in hypnotic work that individuals can and do resist posthypnotic suggestions that they do not wish to perform, except that implicit trust of the hypnotist may promote a behavior out of the ordinary. This is sometimes (especially per Orne) considered more a factor of the relationship between the hypnotist and subject than a matter of any capacity to use hypnosis to coerce a person without their knowledge. The later section on hypnosis and volition will cover this in grater detail.

See the following sources of information on post-hypnotic research, in addition to the Hilgard article in Vol. 16 of Annual Reviews (1965), cited above:

  • W. Wells, 1940, "The extent and duration of post-hypnotic amnesia," Journal of Psychology, 9:137-151.
  • Edwards, 1963, "Duration of post-hypnotic effect," British Journal of Psychiatry, 109: 259-266.
  • Dixon, 1981, "Preconscious Processing" (book)

Various studies have also been done to try to determine what kinds of psychological pressure will cause hypnotic amnesia to be breached, and under what conditions.

Schuyler & Coe, "A physiological investigation of volitional and nonvolitional experience during posthypnotic amnesia," Journal of Personality & Social Psychology, 40(6):1160-9, 1981 Jun was a good example.

Highly responsive hypnotic subjects, who were classified as having control over remembering (voluntaries) or not having control over remembering (involuntaries) during posthypnotic amnesia, were compared with each other on four physiological measures (heart rate, electrodermal response, respiration rate, muscle tension) during posthypnotic recall. Two contextual conditions were employed: One was meant to create pressure to breach posthypnotic amnesia (lie detector instructions); the other, a relax condition, served as a control. The recall data confirmed earlier findings of Howard and Coe and showed that voluntary subjects under the lie detector condition recalled more than the other three samples that did not differ from each other. However, using another measure of voluntariness showed that both voluntary and involuntary subjects breached under lie detector conditions. Electrodermal response supported the subjects' reports of control in this case. Physiological measures were otherwise insignificant. The results are discussed as they relate to (a) studies attempting to breach posthypnotic amnesia, (b) the voluntary/involuntary classification of subjects, and (c) theories of hypnosis.

Pain control (analgesia and anesthesia)

Hypnosis was at one time frequently and sucessfully used for surgical anesthesia. It is still sometimes used effectively for dental work, childbirth, and chronic pain of various types. Pain control is one of the most reliable and most studied of the hypnotic phenomena.

In addition to Hilgard's article in Vol 26 of Annual Reviews (1975) see:

  • Hilgard, Hilgard, Macdonald, Morgan, and Johnson, 1978, "The reality of hypnotic analgesia: a comparison of highly hypnotizables with simulators." The authors find that motivated simulation of hypnotic analgesia is easily distinguished from hypnotic analgesia.
  • Hilgard and Hilgard, 1983, "Hypnosis in the relief of pain" (book)
  • In 'Evaluation of the efficacy and neural mechanism of a hypnotic analgesia procedure in experimental and clinical dental pain,' 4,41-48, Pain, 1977, J. Barber and D. Mayer reported that effective analgesia was produced by a refinement of hypnotic technique, and was not reduced by naloxone. J. Barber, neuropsychiatry at UCLA, seems to have somewhat specialized in this area.
  • Another 1977 study, Stern, Brown, Ulett, and Sletten, 'A comparison of hypnosis, acupuncture, morphine, Valium, aspirin, and placebo in the management of experimentally induced pain,' Annals of the New York Academy of Sciences, 296, 175-193, found that acupuncture, morphine, and hypnotic analgesia all produced significantly reduced pain ratings for cold pressor and ischemic pain.
  • Van Gorp, Meyer, and Dunbar, 'The efficacy of direct versus indirect hypnotic induction techniques on reduction of experimental pain,' International Journal of Clinical and Experimental Hypnosis, 33, 319-328, 1985 (with cold pressor pain).
  • Tripp and Marks, 1986, compared hypnosis and relaxation with regard to analgesia for cold pressor pain in 'Hypnosis, relaxation, and analgesia suggestions for the reduction of reported pain in high- and low-suggestible subjects,' Austrailian Journal of Clinical and Experimental Hypnosis, 33, 319-328.
  • H.B. Crasilneck et al., 1955, "Use of hypnosis in the management of patients with burns," Journal of the American Medical Association, 158: 103-106.
  • D. Turk, D.H. Meichenbaum, and M. Genest, (1983), Pain and behavioral medicine: a cognitive-behavioral perspective, New York: Guilford Press has a review of cognitive-behavioral strategies for pain control in general, not limited to hypnosis.
  • In Larbig W. Elbert T. Lutzenberger W. Rockstroh B. Schnerr G. Birbaumer N. EEG and slow brain potentials during anticipation and control of painful stimulation. Electroencephalography & Clinical Neurophysiology. 53(3):298 -309, 1982 Mar., EEG corrrelates of pain control were studied.

Cerebral responses in anticipation of painful stimulation and while coping with it were investigated in a "fakir" and 12 male volunteers. Experiment 1 consisted of 3 periods of 40 trials each. During period 1, subjects heart one of two acoustic warning stimuli of 6 sec duration signalling that either an aversive noise or a neutral tone would be presented at S1 offset. During period 2, subjects were asked to use any technique for coping with pain that they had ever found to be successful. During period 3, the neutral S2 was presented simultaneously with a weak electric shock and the aversive noise was presented simultaneously with a strong, painful shock. EEG activity within the theta band increased in anticipation of aversive events. Theta peak was most prominent in the fakir's EEG. A negative slow potential shift during the S1-82 interval was generally more pronounced in anticipation of the aversive events that the neutral ones, even though no overt motor response was required. Negativity tended to increase across the three periods, opposite to the usually observed diminution. In Experiment 2, all subjects self- administered 21 strong shock-noise presentations. The fakir again showed more theta power and more pronounced EEG negativity after stimulus delivery compared with control subjects. Contrary to the controls, self-administration of shocks evoked a larger skin conductance response in the fakir than warned external application.

Dermatological responses

Some of the most interesting hypnotic phenomena involve the apparent precision production of subtle skin responses by suggestion. Allergic reactions, pseudo-sunburns, blisters, and weals have been produced by suggestion. In addition, it has long been known that certain highly troublesome skin conditions have been influenced or healed in some people by suggestion (with or without hypnotic induction).

See the following for further information on studies of this:

  • Ullman & Dudek, 1960, "On the psyche and warts: II. Hypnotic suggestion and warts," Psychosomatic Medicine, 22:68-76
  • Rulison, 1942, "Warts, A statistical study of nine hundred and twenty one cases," Archives of Dermatology and Syphilology, 46:66-81.
  • Asher, 1956, "Respectable Hypnosis," British Medical Journal, 1: 309-312.
  • R.F.Q. Johnson and T.X. Barber, 1976, "Hypnotic suggestions for blister formation: Subjective and physiological effects," American Journal of Clinical Hypnosis, 18: 172-181.
  • Mason, 1955, "Icthyosis and hypnosis," British Medical Journal, 2: 57-58.
  • M. Ullman, 1947, "Herpes Simplex and second degree burn induced under hypnosis, American Journal of Psychiatry, 103: 828-830.

Control of bleeding

Experiments with hypnosis during surgery have found that suggestion during and after surgery can reduce bleeding significantly, as well as help with the management of pain.

See Clawson and Swade, 1975, "The hypnotic control of blood flow and pain: The cure of warts and the potential for the use of hypnosis in the treatment of cancer," American Journal of Clinical Hypnosis, 17: 160-169.

Cognition and learning

This is a broad area covering a number of factors that are difficult to separate. In addition to the critical review by Barber in 1965 cited above in (1), see G.S. Blum, 1968. "Effects of hypnotically controlled strength of registration vs. rehearsal," Psychonomic Science, 10: 351-352, which discusses hypnosis as a possible way of reducing rehearsal needed to learn something new.

In some of his publications, researcher Charles Tart discusses the concept of state-specific abilities, including the possibility that some might apply to hypnotic phenomena. See his States of Consciousness, and other related works for more on this.

Enhanced strength or dexterity

The effect of hypnotic suggestion in apparently enhancing physical performance under certain conditions seems to relate to the unusual control over focus of attention available in hypnosis, which permits improved concentration and increased motivation in some athletes, and can be used to modify or lessen the influence of inhibiting beliefs or attitudes. Similar effects are seen when athletes are motivated in other ways, outside of hypnosis.

See T.X. Barber's 1966 paper, "The effects of 'hypnosis' and motivational suggestion on strength and endurance: a critical review of research studies," British Journal of Social and Clinical Psychology, 5:42-50.

Immune Response

It has long been supposed (and in recent years demonstrated experimentally) that emotions and psychological state somehow have an effect on human immune response, but even though detailed mechanisms and the limits of this effect have not been well understood in modern medical science. A recent article in Science News, Sept. 4,1993, pp. 153, describes 'the first solid evidence that hypnosis can modify the immune system far more than relaxation alone."

The report concerns the research of Patricia Ruzyla-Smith of Washington State University in Pullman and her co-workers, who conclude that "hypnosis strengthens the disease-fighting capacity of two types of immune cells, particularly among people who enter a hypnotic trance easily."

This appears to correspond well with and bolster the previous findings related to enhanced 'placebo' (psychosomatic) effects in good hypnotic subjects, in the hypnotic induction situation. However, it does not appear to address the persistent question of whether highly hypnotizable subjects have a unique capacity for psychosomatic regulation, or whether they simply exhibit this capacity common to all of us in a uniquely accessible and convenient way by responding to hypnotic suggestion.

In this research, the psychologists recruited 33 college students who achieved a hypnotic trance easily and 32 students who had great difficulty doing so. Volunteers viewed a brief video describing the immune system and then were assigned to one of three groups: hypnosis, in which they listened to a hypnotic induction asking them to imagine their white blood cells attacking "germ cells" in their body and then performed this exercise through self-hypnosis twice daily for one week; relaxation, in which they floated effortlessly in a large tank of warm water containing Epsom salts and repeated the session one week later; or neither method.

Students who underwent hypnosis displayed larger jumps in two important classes of white blood cells than participants in the other groups. The greatest immune enhancement occurred among highly hypnotizable students in the hypnosis group.

Highly extraordinary experiences while under hypnosis

One of the most persistent of the many controversies surrounding hypnosis is its use in facilitating the recall or (re)experience of events which are distinctly out of the range of what most people think of as usual human experiences. For the present discussion, we might divide these extraordinary experience into three overlapping types:
  1. Experiences which seem extraordinary because what is remembered (while under hypnosis) as having previously happened seems to defy commonly accepted canons of plausibility, such as the controversial UFO abduction phenomenon,
  2. Experiences which, perceived as happening during hypnosis, seem to defy commonly accepted canons of plausibility, or would require a drastic theoretical revision to accept, such as psychic phenomena,
  3. Experiences which seem extraordinary because they have an unusually powerful or lasting effect on the individual, such as certain deeply religious or mystical experiences,

Bizarre remembrances under hypnosis

The veracity of events recalled under hypnosis is considered by most experts today to be problematic to determine. Hypnosis facilitates the recall of details in good subjects, and also facilitates the manufacture of details during recall that were not neccessarily present previously. This in fact is characteristic of recall in general, which has been demonstrated to be far from a permanent and unchanging record, but more a dynamic and adaptive process; a shape-shifting moire pattern of sorts, conforming to inner needs and ongoing mental activity, more than a videotape recording of the precise details of perceptual events.

There is also some evidence that hypnosis may additionally aid in providing 'state-specific' context to aid in the recall of information and experience of which the individual is otherwise normally unaware.

Which of these complex and incompletely understood processes is dominant in the recall of someone's extraordinary memories of seemingly implausible events is extremely difficult if not impossible to determine from the hypnotic session alone.

Neither claims of unimpeachable veracity under hypnosis (the 'hypnosis as truth serum' idea) nor those of hypnosis being completely unreliable in facilitating recall ('false memory') stand up to close scrutiny as a general principle applicable to all cases of controversial hypnotic recall. The best evidence available seems to indicate that hypnotic methods can sometimes be valuable in a number of ways, both to the individual's psychological health and in helping to gather factual information, but that they should not be relied upon by themselves or given special preference over other kinds of testimony for such things as legal evidence, nor considered to be accessing anything like a perfectly faithful permanent record of past perceptual events.

This section closes with an illustrative philosophical excerpt from a recent book investigating perception, memory, and consciousness, based on years of observation of synesthesia (cross-sensory perception); "The Man Who Tasted Shapes: A Bizarre Medical Mystery Offers Revolutionary Insights into Reasoning, Emotions, and Consciousness," Richard E. Cytowic, MD, Jeremy Tarcher/Putnam Publishing 1993, ISBN 0-87477-738-0:

"While pointing out the overlap between emotion and memory, I want to emphasize that memory is not simply a fixed look-up table. It too is a creative process during which the state of the brain's electrical fields change. The sensory cortices generate a distinct pattern for each act of recognition and recall, with no two ever exactly the same. They are close enough to cause the illusion that we understand and have seen the event before, although this is never quite true. Each time we recall something it comes tainted with the circumstances of the recall. When it is recalled again, it carries with it a new kind of baggage, and so on. So each act of recognition and recall is a fresh creative process and not merely a retrieval of some fixed item from storage."

"Furthermore, persons, objects, and events are not perceived in their entirety but only by those aspects which are, have been, or can be experienced and acted upon by an observer..."

"... All that we can know about anything outside ourselves is what the brain creates from raw sensory fragments, which were actively sought by the limbic brain in the first place as salient chunks of information..."

"... Put in a more familiar context, artists and creative writers look at the world in a certain way. It is the same world that everyone else sees, but seen differently. Contemporary people often call artists weird because they do not seem to be seeing the same things that the majority sees. It is critical to realize that the sensory gateways that feed into the brain establish their own conditions for the creation of images and knowledge. Artistic giants knew full well that their visions were not shared by most people. Even when persecuted or abandoned because of their vision artists persist. That is all the can do because their visions are their reality, and for many of us they subsequently become our reality when we experience their art."

(copyright (c) Richard E. Cytowic, MD)

Psychic phenomena under hypnosis

There are a number of links between the sorts of situations commonly associated with hypnosis, and the experience of what are often called 'psychic phenomena,' (herein primarily meaning apparent extrasensory perceptions, and psychokinesis, but also such related experiences as apparitions mediumistic phenomena, and such strange occurrances as the apparent suspension of death).

Hypnosis has a strong historical connection with spiritualism, as evidenced partly by the shared traditional emphasis on 'trance,' especially 'trance' appearing as a stupor (contrasted with the confusing notion of an 'alert trance' or 'waking trance' in some kinds of hypnotic situation). Spiritualism, in turn, has very strong associations with both the origins of various schools of psychology, and modern parapsychology, and the study of 'psychic phenomena' in general. The reason for quoting that term here is to emphasize that the term originally meant such subtleties of mental life as what we today often think of as the'subconscious' or 'unconscious' mind, rather than specifically and exclusively such things as ESP, hauntings, or poltergeists. At the time, it seems there had been less of a feeling that there was a distinct difference in plausibility between 'unconscious processes' and those today generally considered paranormal. Because of this, the term may tend to be ambiguous when used in a discussion where a wide variety of experiences are being included.

Early (circa late 19th century, early 20th century) psychology was largely a philosophical endeavor, which included a wide range of areas of investigations that were grouped in ways that might seem a little strange today. For example, the American Society of Psychical Research (ASPR), today probably thought of mostly as having been a pioneering organization in the study of the paranormal, devoted a great deal of its early efforts (and an explicit section of its charter) to studying what we today usually consider mundane aspects of hypnosis.

Hypnosis has thus long had a popular traditional association with such controversial psychic phenomena as ESP, PK, poltergeist activity, and clairvoyance, as well as various forms of occultism and some kinds of religious healing rituals.

Of particular pertinence here, there is also a tenuous but persistent experimental link between hypnotic processes and laboratory psi. The link is particularly prominent in anecdotal evidence, but this is often of questionable reliability, for reasons that will be described here. It is in the more controlled laboratory psi data that the more truly demonstrable anomalous results appear that give us cause for further investigation.

First, the difficulty with this sort of experiment, and the kinds of protocols and controls required should be recognized. While the open-minded researcher of anomalies might not wish to reject the useful subjective verbal reports of hypnotic subjects, they also have to contend with the remarkable subtlety of non-paranormal (conventional sensory) human perception and communication.

Milton Erickson, for example, described an experiment with hearing impaired 'lip readers.' He discovered that they actually read a much richer panorama of cues than simply the moving lips. The lip reading subjects would sit with their backs to a blackboard on which there were various geometric designs. The designs were then covered with sheets of paper. In front of the lip readers sat a group of non-hearing-impaired participants, who were instructed to look at the blackboard and say and do nothing. Someone else removed the paper covering the geometric symbols, one at a time. The lip readers were instructed to write down anything that they read from the participants in front of them who were observing the geometric figures.

The lip readers were able to "read" the names of the geometric figures apparently from their partner's faces, with varying degrees of accuracy. One subject, a diagnosed paranoid psychotic, who believed they heard other people's thoughts about them, was reported as having perfect accuracy.

Erickson applied this insight to his hypnotic technique, by recognizing the significance of messages he himself didn't realize he was giving. A similar analysis has frequently been applied to anecdotal reports of cases of apparent telepathy, but where 'cold reading', or the skill of gathering information surreptitiously through subtle but conventional sensory clues, appears to be a likely factor.

Someone might actually suggest that the paranoid psychotic patient in this particular experiment, and some or all of the other hearing-impaired patients, were actually employing some telepathic faculty to some degree. But most interpretations would probably focus on the use of subtle clues that the participants observing the blackboard were unaware of providing. The nature of hypnotic communication ('rapport') is such that the participants are particularly well attuned to the nuances of each other's movement, speech and expression. This, combined with the lip readers' existing capacity for attending to subtle body language, contributes to the appearance of an even more extraordinary, even paranormal, information transfer, and makes it more difficult to sort out the precise mechanisms of information transfer involved.

Modern psychological reviews might also focus on the hypothesis that the paranoid psychotic subject was likely dissociating their perception of what they were reading from their awareness of its source (rather than the obvious appearance of receiving it from an extrasensory source). This resembles the dissociation theory of how trance mediumistic (trance channelling) behaviors and some religious experiences (such as hearing the voice of God) may occur, at least in some cases. The concept of cognitive dissociation is a central one to many modern psychological descriptions of hypnotic and peripheral phenomena, as we will see in more detail later. In particular, we will see that dissociation provides an extremely useful description, but not neccessarily an adequate explanation of all of the data.

Today, most psychologists, and virtually all of those investigators known as parapsychologists, are aware of the complexity of human perception under even conventional circumstances. They would generally tend not to consider a psi hypothesis to be demonstrated in this sort of situation, given the apparently demonstrated correlation of exceptional body language reading skills and high hit rates. This is of course entirely different from demonstrating that a psi faculty is not operating. Just that the experimental situation in this particular case does not provide evidence of psi.

But there are other experimental results, with protocols more specifically designed to rule out subtle conventional sensory communication. These give us reason to at least consider and test a psi hypothesis, with an eye toward ruling out subtle body reading effects, in hypnotic situations. It appears from some results that under certain kinds of conditions hypnosis may at least be slightly conducive to anomalous information transfer, even when subtle cues are eliminated.

One well known difficulty of even this result, though, is that it is not clear whether hypnosis is facilitating some elusive 'ESP' faculty in some general way, or more specifically improving the percipient's ability to perform on the particular kinds of tests in use. In other words, the dramatic interpretation of hypnosis as an altered state in which paranormal capacities are provided or enhanced may not be the best or only explanation, even if the psi hypothesis itself were to receive growing experimental support. There is also the crucially important matter of just exactly what it is about the process of hypnotic induction and its effects on the subject that changes hit rates in certain laboratory psi tests.

In another section, we briefly review T.X. Barber's work demonstrating that most if not all of the unusual phenomena reported during hypnosis are also seen under other conditions. He and his colleague Sheryl Wilson in their work on the theory of the 'Fantasy Prone Personality' also provide us with another link between psi and hypnosis, the observation that there are distinct similarities in personality variables between people who are excellent hypnotic subjects, and those who report large numbers of psychic experiences.

It should be emphasized here that this theory does not support the once popular notion that good hypnotic subjects are simply gullible or neurotic, or otherwise mentally ill; as no correlation with any of these personality variables has ever been determined. Rather, the FPP theory paints a picture of natural visionary individuals with a rich inner life and often extraordinary psychosomatic responses, but who are perfectly well able to distinguish their vivid fantasy life from reality, just as most of us can distinguish a dream from a memory of actual events, most of the time.

In other words, among the factors that the FPP does NOT correlate with well at all is any diminished capacity for reality testing. This should be born in mind particularly because of the popular connotations of the term 'fantasy-prone,' and the questionable veracity of recollections occurring under hypnotic procedures. A report from an FPP subject is not inherently either more or less reliable than one from other subjects, in or out of hypnosis. Their rich mental life does not neccessarily intrude on their external perceptions, except under various very unususal kinds of conditions, such as spontaneous hallucination triggered by hypnotic suggestion.

Additionally, there is the complex psychological question of whether the individual interprets their experience as 'real' or 'imagined.' When an LSD user comes down from their trip, they don't generally continue to believe that their face was melting or that the sky actually changed to flourescent green during their experience, they distinguish it as an 'altered state.' However, during the trip, the altered perception may be quite convincing.

In hypnotic extraordinary experiences, we find both cases where the individual believes that their perceptions were due to an altered state, even though it seemed real at the time, and those where they believe something quite bizarre actually happened, not the result of an unusual perceptual state. And the two types of cases are not at all easy to distinguish by any means other than relying on the report of the subject.

It has also been observed that even a polygraph is of extremely limited value in distinguishing whether a bizarre occurrance actually happened to an individual or was hallucinated or 'confabulated.' In many cases, the individual believes that a hallucinated or hypnotically constructed event happened, when unambiguous independent historical records indicate that it did not.

The particular conditions under which spontaneous hallucination can occur, and under which they can be confused with external perceptual experiences are not well known, nor is there any known method of distinguishing a spontaneous hallucination from an external sensory perception. Even theories of how drug action (e.g. LSD) causes hallucinations are highly speculative, and spontaneous hallucinations are much more slippery.

Two current theories of spontaneous hallucination concern changes in the chemical environment of endogenous neurotransmitters or neuromodulators which influence perception (endorphins and serotonin being the most commonly cited); and possibly some unique mode of function of temporal or temporolimbic brain pathways, perhaps influenced by electromagnetic fields.

How these unusual brain conditions relate to psychic phenomena and to other observations related to hypnosis in general is not yet well established.