Hypnosis refers to a state or condition in which an individual becomes highly responsive to suggestions. The hypnotized person 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. A profoundly responsive subject hears, sees, feels, smells, and tastes in accordance with the hypnotist's suggestions, even though they may be in direct contradiction to the actual stimuli impinging upon the subject. Further, memory and awareness of self can be altered by suggestions. All of these effects may be extended posthypnotically into the individual's later waking activity. It is as if suggestions given during hypnosis come to define the subject's perception of the real world. In this sense the phenomenon has been described as a "believed-in fantasy."

Austrian physician Anton Mesmer discovered hypnotism in the 1770s. Believing the nervous system to be magnetized just as the Earth is, he called the phenomenon "animal magnetism." Practicing in Paris, Mesmer attracted a large following who believed that animal magnetism or mesmerism, as it was popularly called was a cure for all manner of physical and mental ailments. In the 1840s, Scottish surgeon James Braid, who coined the term hypnosis from the Greek word for sleep, advanced the study of the subject. He developed more precise techniques and, more importantly, delineated the neuromuscular processes that occur in a patient during the induction of a hypnotic trance. Like Mesmer, however, he was prone to over-inflate the efficacy of medical cures that could result from hypnotic treatments.

Subsequent physicians in the 19th century elaborated the theory that in a hypnotic trance a patient's will was paralyzed and that unconscious mental processes could be observed. This led to the concept, developed by Sigmund Freud and others, that through hypnosis a patient's repressed thoughts and desires could be revealed. This concept remained dominant until well into the 20th century, when alternative theories arose: that hypnosis is nothing more than a deep form of relaxation, or that patients under hypnosis are merely "role-playing," or that the hypnotic state is only one more level of the human system of cognition. In fact, while much is now known about the physiology of the hypnotic trance, its precise causes are still little understood.

Typically, when a responsive individual is hypnotized, the subject is asked to relax and to focus attention (usually on some object). The hypnotist says, in a quiet, compelling tone, that relaxation will increase and the eyes will become tired. Soon the subject's eyes show exaggerated signs of fatigue. When it is suggested that they will close, they do, and the subject begins to show signs of a profound relaxation, with quiet, regular breathing, that superficially resembles sleep. It may now be suggested that the eyes are so heavy that the subject does not care to open them and could not do so even if that were attempted. When invited to try, the subject finds, often with surprise, that this is so.

Through analogous suggestions, the subject's experience may be altered in virtually every sensory modality. The memory for ongoing events may be interrupted, but the apparent reliving of events that transpired in the individual's past may be facilitated. That is, age regression can be induced by suggesting that the subject is growing younger and younger. Gradually, the subject will begin to respond in the manner of a child and may describe events, people, rooms, and feelings as if currently reliving an episode of past life. The subject's descriptions and total behavior may take on characteristics seemingly appropriate to the age to which the subject has regressed.

Response to posthypnotic suggestion may be demonstrated by telling the hypnotized subject to forget what has occurred and, further, that after awakening, the individual will carry out a specific action at a particular time or in response to a prearranged signal. When awakened and asked what has happened, the subject will be unable to describe the events that have just transpired. The bulk of these memories can, however, easily be recovered by suggesting that the subject will remember all that has occurred.

Stage hypnotists capitalize on the fact that posthypnotic suggestions may include apparently embarrassing actions. While the posthypnotic action suggested during hypnosis will be carried out at a prearranged signal without the subject being aware of the reasons for the action, however, the subject will do so only as long as the action is not truly unacceptable.

The hypnotic state is a response of normal individuals, but there are wide individual differences in the ability to respond. The capacity to be hypnotized resides in the individual rather than in the hypnotist's technique and is one of the many basic psychological characteristics of normal individuals. This capacity does not seem directly related to a particular personality type, although it is related to the ease with which an individual can become absorbed in fantasy while ignoring the real world. However, it is not possible to hypnotize a person who does not wish to be hypnotized.

Although the hypnotized individual may at times appear superficially asleep and will respond in a way that may initially appear slow and trance-like resembling the behavior of the spontaneous sleepwalker the individual is physiologically awake at all times. In contrast to the true sleepwalker, the subject's brain waves are those of a waking individual. Similarly, although the hypnotized subject may be instructed to ignore surrounding events and will apparently be unaware of their existence, such material does register and can be shown to exert an effect on the subject.

Even deeply hypnotized, an individual will not only refuse to act against strongly held moral, ethical, or religious beliefs, but can, if choosing to do so, resist responding to any specific suggestion. For example, despite suggestions to tell the truth, it is possible for the subject to purposively lie with little more effort than in the normal waking state. Further, although age regression is useful in psychotherapeutic treatment, the memories called forth may validly reflect the individual's feelings about past events. The events relived, however, may or may not be historically accurate. Although compelling both to subject and to observer, these memories often are instead a combination of many events, not only from the same epoch but also confounded by later experiences a matter of concern if historical accuracy is important, as in legal matters.

Hypnosis is not an independent science or art. Rather, it is a technique useful in the context of medical, psychological, or dental treatment. It is used to control both acute pain as in childbirth, skin transplants, dental procedures, and the treatment of burns and chronic pain. There are many other medical applications, including the treatment of some skin disorders, allergies, and intractable insomnia. In legal use, most states in the United States permit the introduction of hypnotically induced evidence. The problem of induced false memories, however, has become a matter of controversy, and courts in several jurisdictions now bar such testimony or impose procedural safeguards on its use.

In psychiatric or psychological therapy, hypnosis may be used to facilitate recall of traumatic events that have been pushed out of mind and to help the patient deal with neurotic symptoms. Hypnosis, particularly as used in treatment, is a cooperative enterprise that depends upon the patient's ability to respond. It is important for the patient to understand this. Hypnosis has been used with varying degrees of success in such disorders of self-control as obesity and addictions. It has been particularly useful in the treatment of phobias and functional disorders of memory. Hypnosis and relaxation exercises have been integrated into many behavioral as well as psychodynamic treatment approaches. The use of hypnosis to "suggest away" symptoms, however, has a more limited application than is generally recognized.

Martin T. Orne

Bibliography: Alman, B. M., Self Hypnosis (1992); Chaves, J. F., and Spanos, N. P., eds., Hypnosis: The Cognitive Behavioral Perspective (1989); Hadley, Josie, and Studacher, Carol, Hypnosis for Change (1989); Hilgard, E. R. and J. R., Hypnosis in the Relief of Pain (1994); Kirsch, Irving, et al., Handbook of Clinical Hypnosis (1993); Kroger, W. S., Clinical and Experimental Hypnosis in Medicine, Dentistry, and Psychology, 2d ed. (1977); Rhodes, Raphael, Hypnosis (1995); Yapko, M. D., Trancework: An Introduction to the Practice of Clinical Hypnosis (1990).