While certain hypnosis stages are characteristic of the hypnotic trance, their manifestations vary with the individual subject and with the depth of the trance, that is, whether light or deep hypnosis. Even so, hypnosis stages and phenomena usually found in deep hypnosis may occur in light hypnosis and vice versa, depending upon the subject’s personality and psychological needs at the time. Most normal people develop light hypnosis easily, and at least 70 percent of all subjects, with adequate training by which is meant repeated hypnosis and thus continued practice in going into the hypnotic state can develop deep trances.

For medical purposes either the light or the deep trance may be satisfactory, depending upon the nature and the character of the therapeutic goal to be achieved. Also, should the light trance be unsuitable, recourse may at once be had to the progressive induction of a more profound trance. Experience is the only able teacher of what type of trance is necessary, and failure to secure results in the light trance can always be corrected by resorting to the deep trance.

The phenomena of the trance of most interest to the medical man are several. Foremost of these is rapport, a condition in which the subject responds only to the hypnotist and is seemingly incapable of hearing, seeing, sensing or responding to anything else unless so instructed by the hypnotist. It is in effect a concentration of the subject’s attention upon, and awareness only of, the hypnotist and those things the hypnotist wishes included in the trance situation, and it has the effect of dissociating the subject from all other things. The hypnotist may transfer this rapport by appropriate suggestions.

Catalepsy is a second phenomenon which illustrates clearly the tremendous psychosomatic significance of hypnosis. This is a peculiar state of muscle tonus which parallels cerea flexibilitas of the stuporous catatonic patient. The subject holds his arm up in the air, maintains any awkward position given by the hypnotist, and shows a failure of normal fatigue reactions. Concomitant with it are a loss of the swallowing reflex, a dilatation of the pupils, a loss of facial mobility, and a definite slowing of all psychomotor activity. Yet, upon instructions by the hypnotist, the subject can perform adequately at a motor level equal to the waking capacity and often at a level that transcends it.

Sensory changes, or alterations in sensory behavior, of both a positive and a negative character are frequent and often undetected. Blindness and deafness to things not included in the hypnotic situation often develop to a degree that resists clinical tests. There also occur spontaneously anesthesia, analgesia, and other types of sensory disturbances. Additionally these sensory phenomena can be induced by appropriate suggestion. Their presence is often of great importance in therapy, since they serve so well to make subjects appreciate their trance depth and to direct the hypnotist’s attention to unexpected psychosomatic implications that need to be considered in the hypnotic procedure.

Amnesia and other memory alterations constitute another type of hypnotic phenomena of extreme interest to the medical practitioner. Usually after a deep trance subjects have a more or less complete amnesia for all trance events. This amnesia can be controlled by the hypnotist through instruction to the subjects, or the subjects themselves can deliberately set about recovering the amnesic material. In either instance the forgotten memories may be recovered in full or in part according to the instructions given or in accordance with each subject’s needs. This amnesia is of profound importance in psychotherapy since it permits the therapist to deal with painful memories without arousing the subject’s waking resistance and defensive reactions. In contradistinction to hypnotic amnesia is the capacity of the hypnotic subjects to develop hypermnesia that is, increased memory ability and to recover memories of past experiences long forgotten and actually inaccessible in the waking state. Traumatic, painful, forgotten experiences and memories that often constitute a point of origin in serious personality disturbances are frequently readily accessible under hypnosis, can be easily recalled by the patient, and a foundation laid in the trance state for their integration into the waking life of the patient. The importance of the recovery of lost memories in psychotherapy is fully established, and hypnosis often proves a royal road to those memories, although it still leaves the task of integrating that memory into the waking life of the patient a painstaking task for the therapist. In addition to this recovery of past forgotten memories, hypnosis can enable subjects to recover memories of lost experiences in phenomenal and minute detail ordinarily not possible. By such hypermnesia minor clues to a personality disturbance or emotional conflict otherwise not accessible become available.

Based to some degree upon the mechanisms of amnesia and hypermnesia is another phenomenon termed regression. By this is meant the capacity of hypnotic subjects, upon suitable suggestions and instructions, to develop an amnesia for a definite period of life and to revivify and reestablish the memories and patterns and habits of an earlier period. Thus, a 25-year-old subject can be induced to develop a profound amnesia for all events of his life subsequent to the age of 15 years and to reassume his actual modes and habits of behavior and response belonging to his 15-year-old level of development.

Suggestibility, necessarily a primary feature of hypnosis, is always present and constitutes the basic consideration upon which the trance and its attendant phenomena are based. Additionally, suggestibility plays another role after the trance is induced, in that any desired behavior can be suggested to the subject and an adequate performance can be secured, provided that the suggestions are not offensive to the subject. Thus, in the medical situation, the recovery of memories, the development of amnesias, identifications, and anesthesias, the causing of dreams, emotional conflicts, hallucinations, disorientation, and so forth can be produced in the patient during the course of therapy as a measure of meeting problems, developing insights, and reorganizing the psychic life.

Automatic writing and crystal-gazing, two somewhat comparable phenomena, both long known but superstitiously regarded, are easily elicited in the trance state and are often of great value in psychotherapy. In response to suggestion the subject writes automatically and without awareness and thus may be induced to uncover amnesic material or to disclose necessary information otherwise inaccessible or which the personality is not yet strong enough to face. Or the subject may see vividly and clearly in a crystal the enactment of long-forgotten traumatic experiences and thus achieve a realization of their actuality and reality to him as a person.

Posthypnotic suggestion is one of the most significant of all hypnosis stages and phenomena. By this measure subjects can be given instructions in the trance to govern their future behavior, but only to a reasonable and acceptable degree. Thus, the subject may be instructed that at some future date he is to perform a certain act. At the specified time the subject executes his bidding, but believes his performance self-ordered and spontaneous. As a therapeutic measure, posthypnotic instructions are of great value, but if improperly used they are ineffectual and futile. They need to be used primarily as a measure of providing the patients with an opportunity to develop insight and to integrate their behavior.

Somnambulism is another form of hypnotic behavior always significant of a deep trance state. In this condition subjects behave and respond as if they were wide awake and may even deceive observers with their seeming wakefulness. This state is the most suitable for the deeper forms of psychotherapy and can be induced by repeated hypnosis in at least 70 percent of all subjects.