Orne, M. T., & Dinges, D. F. Hypnosis. In G. Adelman (Ed.), Encyclopedia of neuroscience, Vol. I . (2vols.) Cambridge, MA: Birkhauser Boston, 1987. Pp. 509-510.


Martin T. Orne and David F. Dinges

Hypnosis is the state or condition whereby an individual alters perception, memory, or mood in response to suggestions administered in a suitable context. The induction of hypnosis typically occurs when a responsive individual, after agreeing to be hypnotized, is asked to relax and focus attention on some object and on the hypnotist's voice. It is usually suggested that the eyes will become tired, and as they show exaggerated signs of fatigue, that they will close and the subject will go into hypnotic “sleep.” It may then be suggested that the subject's eyes are so heavy that they cannot be opened, even if it were attempted, and the responsive individual will experience a partial or complete inability to open the eyes. Just as heaviness and transient cataplexy may be induced, suitable suggestions may influence every form of perception, as well as cognitive and emotional processes.

Although the closed eyes and regular breathing of the hypnotized individual may give the superficial appearance of sleep and the subject's behavior may seem slow and trancelike, resembling the behavior of a spontaneous sleepwalker, the individual is physiologically awake at all times. The electroencephalogram of a hypnotized subject is that of an awake, relaxed individual. Nonetheless, relaxation itself is not an essential characteristic of hypnosis. It has been induced in alert and active subjects, as for example, when they were riding an exercycle. In such experiments subjects have demonstrated the typical hypersuggestibility of the hypnotized individual while continuing to put out a considerable amount of work.

The capacity to be hypnotized, contrary to earlier misconceptions, resides in the subject rather than in the hypnotist. Because hypnosis is under the volitional control of the subject, an individual cannot be hypnotized against his or her wishes. Further, once hypnotized an individual cannot be forced to commit acts that he or she would not perform outside of hypnosis. However, the effects of hypnosis need to be distinguished from those due to the context in which it occurs. For example, when hypnosis is used in a therapeutic context, the patient trusts the therapist/ hypnotist and under these circumstances a wide range of behaviors might be elicited that would otherwise be unacceptable to the subject.

One of the most dramatic effects of hypnosis that has been empirically documented both in the laboratory and in the clinic is its use in the control of pain that has a clear organic etiology. For instance, it has been used successfully to block the discomfort of bone marrow aspirations in leukemic patients, and to provide relief during the debridement of burns. It has also been employed as the sole anesthetic in operations ranging from thyroidectomies to caesarean sections to open heart surgery.

While the use of hypnosis as anesthesia documents that psychological processes can block the appreciation of pain, only some individuals can respond to hypnosis profoundly enough to tolerate surgery. This is because, like other personality dimensions, there are wide differences among people in their ability to respond to hypnotic suggestions. This capacity, known as hypnotizability, is normally distributed in the population. It does not appear to be directly related to any other personality dimension, with the exception of the extent to which an individual can become totally absorbed in fantasy while temporarily ignoring the world. This association is expected because during hypnosis the subject suspends disbelief and generally accepts and responds to suggestions uncritically. It is as if suggestions given during hypnosis come to define the individual's perception of the real world. In this sense, the phenomenon has been described as a "believed-in fantasy."

Precisely how the hypnotized individual behaves is a function of the person's beliefs about hypnosis. Thus, the behavioral attributes of the hypnotic phenomenon are in large part culturally determined: hypnotic-like events with different behavioral characteristics have been identified in many cultures. For example. hypnosis-like procedures among the Egyptians were already described on the Ebers Papyrus. Similarly, the sleep healing at the Temple of Asclepius in ancient Greece can be conceived as analogous to hypnosis. Modern hypnosis is usually traced to Anton Mesmer despite the fact that the behavior of the mesmerized subject was quite different from that of the hypnotized subject today. Many of the controversies about hypnosis can best be understood by recognizing that the hypnotized individual will tend to manifest the behavior that the subject and the hypnotist believe to be characteristic of hypnosis.

Rather than being defined by the behavior per se, hypnosis refers to the process by which the person becomes highly responsive to suggestions. The individual seems to follow instructions in an uncritical, automatic fashion and to attend closely only to those aspects of the environment made relevant by the hypnotist. If highly responsive, the subject hears, sees, feels, smells, and tastes in accordance with the suggestions given, even though these may be in direct contradiction to the actual stimuli that impinge upon the individual. Thus, the subject may identify a vial of ammonia as a sweet-smelling rose. In suitable individuals these effects may be extended beyond hypnosis by giving posthypnotic suggestions to the person during hypnosis. Similarly, an individual can learn to experience this process without a hypnotist, using any one of a variety of techniques. This is referred to as self-hypnosis.

Although the suggested alterations in perception or memory are compellingly real to the hypnotized individual, and the subject may ignore surrounding events and apparently be unaware of their existence, such events do register in the neurophysiology of the nervous system and can be shown to exert effects upon the subject. For example, the hypnotized individual may not perceptually appreciate a painful stimulus, despite the fact that the autonomic nervous system responds to the event. Research has shown that whatever mechanism is involved in this perceptual alteration, it apparently is not mediated by the endogenous endorphins, because naloxone has not been shown to prevent hypnotic analgesia. Moreover, research suggests that the factors that account for the effectiveness of hypnosis in pain control do not appear to be the same as those of acupuncture. biofeedback, drug placebo. Analgesics, or tranquilizers. Although differential cortical hemispheric activation (especially increases in right-hemisphere activation) has been implicated in some studies with hypnotized subjects, other studies have failed to replicate the finding and there is little data to suggest that the phenomenon can be accounted for by shifts in hemispheric dominance. The neurophysiological basis for hypnosis has yet to be elucidated.

Hypnosis is a technique useful in the context of medical or psychological treatment: it is not an independent science or art. Its use as a treatment modality (but not as a means of enhancing recall) has been endorsed by the American Medical



510 Hypnosis

Association, the American Psychiatric Association, and the American Psychological Association. In addition to its use in the treatment of acute and persistent pain, there are many other medical applications of hypnosis, including the treatment of some skin disorders, allergies, and intractable insomnia. It has been used with limited success in such disorders of self-control as obesity and smoking, and with little or no effect in the treatment of addictions.

In psychiatric or psychological treatment, hypnosis may be used to facilitate the experience of feelings associated with past traumatic events that have been pushed out of mind, and thereby help the patient deal with neurotic symptoms; it does not, however, enhance the accuracy of memories obtained from its use. Hypnosis, especially as it is used in treatment, is a cooperative enterprise that depends upon the patient's ability to respond. It is particularly useful in the treatment of phobias, anxiety states, and a number of psychosomatic disorders. Hypnosis and related techniques have been integrated into many behavioral as well as psychodynamic treatment approaches. However, the use of hypnosis to suggest away symptoms has a more limited application than is generally recognized.

The technique of inducing hypnosis is readily learned, but even extensive experience with induction does not provide the necessary knowledge to use hypnosis appropriately in therapy. Health professionals employ hypnosis in their area of competence and should be equipped to use a variety of other treatments as well as hypnosis so that they can choose the one most appropriate for a particular patient. Broad diagnosis and therapeutic skills are indispensable to avoid inappropriate and potentially dangerous use of hypnosis in treatment.

See also Activation, Arousal, Alertness, and Attention; Relaxation Response, Physiology

Further reading

Fromm E. Shor RE (1972): Hypnosis: Research Developments and Perspectives. Chicago: Aldine-Atherton

Hilgard ER. Hilgard JR (1975): Hypnosis in the Relief of Pain. Los Altos. Calif: William Kaufmann

Sheehan PW. Perry CW (1976): Methodologies of Hypnosis: A Critical Appraisal of Contemporary Paradigms of Hypnosis. Hillsdale NJ:Lawrence Erlbaum Associates

The preceding paper is a reproduction of the following entry (Orne, M.T., & Dinges, D.F. Hypnosis. In Encyclopedia of neuroscience, Vol. I. (2 vols.) Cambridge, MA: Birkhauser Boston, 1987. Pp. 509-510.). Now an imprint of Springer-Verlag, it is reproduced here with the kind permission of Springer-Verlag.