Clinical & Experimental Hypnosis: In Medicine, Dentistry, and Psychology, 2nd Edition

8. Recognition of the Depth of the Hypnotic State

As early as 1930, R.W. White made use of specific responses to suggestions given during hypnosis as a means of determining a score.19 The Davis and Husband classification, published in 1931, depends on a point-scoring system and was the rating scale most commonly referred to in the older literature.4 In 1947, LeCron and Bordeaux introduced a more involved scoring chart separated into six divisions instead of five, the last being a deeper stage which is seldom seen—the plenary or hypnotic coma state.9

On the basis of objective and subjective clinical signs, the first part of the light stage is characterized by a pleasant state of restfulness. The subject hears surrounding sounds, is well able to control his thoughts, and experiences no impairment of the senses. After spontaneous eye closure, muscle tension is slightly decreased and motor activities of the limbs are easily carried out. This is followed by drowsiness and lassitude; the carefully lifted arm drops limply. There is some difficulty in opening the eyes or moving the limbs. It has been noted, however, that subjects entering into hypnosis do not have the undulatory eyeball movements that characterize a person falling asleep.20

As the hypnosis deepens and the so-called medium stage is reached, the relaxation becomes more marked; the respirations become deeper and regular; some loss of motor activity occurs; the lifted arm remains upright but slowly falls (light catalepsy), and there is a loss of interest in extraneous environmental sounds. As this stage deepens, catalepsy of the limbs is more marked; spontaneous analgesia can be augmented by appropriate suggestions; the subject's thoughts begin to wander, and he now concentrates more on the words of the operator. Inability to move the limbs is noted at this stage, and the automatic movements become more pronounced.

In the deep stage, negative and positive hallucinations can be produced readily; partial or complete amnesia is present, and suggestions of active and passive motor reactions are easily affected. As this stage deepens, positive and negative hallucinations of all types can occur with the eyes open, and these can be maintained posthypnotically; total amnesia is generally present as are age regression, revivification, and other phenomena characteristic of the somnambulistic state. In several thousand patients, Crasilneck and Hall have noted that an area of pallor about the lips, just beyond the mucocutaneous border, is often indicative of somnambulism.3 Noting this phenomenon obviates the need for challenging the patient to open his eyes or resorting to anesthesia. Another indicator is the Friedlander-Sarbin scale,6 from which Weitzenhoffer and Hilgard developed their scales.16,17,18 These are described below.

It is difficult to measure objectively the depth of hypnosis. We do not know whether characteristic hypnotic behavior is due to the approach used or whether the various depths are the result of the expectations of the hypnotist and subject. The various rating scales are used primarily for experimental work and are only of limited value to the experienced clinician. All rating scales are, at best, arbitrary divisions. Sometimes it is difficult to state with certainty that the subject is in a light or a medium stage of hypnosis. An experienced operator, however, can often make a close approximation.

In line with this, Spiegel has constructed a Hypnotic Induction Profile (HIP).14 The two primary components of the HIP are eye roll and arm levitation. Each is given a score of 0 to 4; the average of the two is the profile score. An entire profile is complete when the patient has similar eye-roll and arm levitation scores. It is a rapidly administered test lasting 5 to 10 minutes and includes an assessment of the eye roll and two other hypnotic phenomena, namely, the ideomotor and posthypnotic responses. Amnesia for the signal that terminates the posthypnotic suggestion increases the rating. Sometimes only the eye-roll is given. The amount of sclera showing as the patient closes the eyes presumably indicates the subject's responsiveness to hypnosis. The HIP will be described in more detail in Chapter 9.

The Stanford Hypnotic Clinical Scale (SHCH) was introduced recently by Hilgard and Hilgard.8 Here too, however, the items in the scale are not a constant. A subject in light hypnosis may experience some of the phenomena of deep hypnosis.5 The final score is not always a reliable indicator of hypnotic responsivity. The profile scales, however, might be helpful in learning more about an individual's special capabilities.

For teaching purposes, five divisions of the various stages of hypnotic susceptibility are satisfactory, with three of these being sufficient for clinical purposes:

1.   Insusceptible;

2.   Hypnoidal (precursor to hypnotic state—no symptoms);

3.   Light stage;

4.   Medium stage;

5.   Deep stage.

Other noteworthy scales include the Stanford Hypnotic Susceptibility Scales (SHSS:A, SHSS:B, and SHSS:C) of Weitzenhoffer and Hilgard;1617 the Stanford Profile Scale of Hypnotic Susceptibility (SPS), with two forms;18 and derivatives of these, such as Shor and Orne's Harvard Group Scale of Hypnotic Susceptibility13 and London's scale for children, the Children's Hypnotic Susceptibility Scale (CHSS).10Susceptibility is defined as the depth of hypnosis achieved under standard conditions of induction.

In the development of these scales, the standard procedures for construction of psychometric tests have been carefully followed. Samples of hypnotic phenomena were sought, a standardized induction procedure was worked out, and norms were obtained by testing more than 300 subjects. Reliability of the scales was studied by the test-retest method, with alternate forms and different hypnotists being used. Satisfactory coefficients were obtained. Validity was assessed by correlating scores on each item with the total score for the scale (minus the score for the particular item). Only one item proposed for inclusion, passive arm catalepsy, was discarded; it was found not to correlate positively with other measures of susceptibility.

Certain differences should be noted in the three Stanford Hypnotic Susceptibility Scales. Items in the SHSS:C are arranged in an ascending order of difficulty, and it contains more items of a cognitive nature (e.g., positive and negative hallucinations, dreaming, and age regression) than are found in the SHSS:A and SHSS:B.

The Stanford Profile Scales were devised in order to provide separate scores on six subscales: agnosia and cognitive distortion, positive hallucinations, negative hallucinations, dreams and regressions, amnesia and posthypnotic suggestions, and loss of motor control. These items are difficult to assay, and the SPS is intended only for those subjects who score 4 or more points on the SHSS:A or SHSS:B (the mean of SHSS:A is 5.62). A full diagnostic use requires the administration of both forms, each of which contains nine items and includes the scores from SHSS:A. The Stanford group has constructed an indispensable set of tools for many, if not most, kinds of scientific research in hypnosis. It follows the accepted technics of test construction.

To assay the hypnotizability of a group, Shor and Orne developed the Harvard Group Scale (HGSHS:A).13 With this scale it is possible to test a whole class in one session. Barber and his associates have developed the Barber Susceptibility Scale (BSS) to test quasi-hypnotic behavior without prior induction of formal hypnosis.1,2 Both the BSS and the SHSS:A are satisfactory for preliminary subject selection but limited as criteria for the range of hypnotic responsiveness.12 The Harvard Group Scale of Hypnotic Susceptibility, form A (HGSHS:A) has been assayed and found to possess adequate reliability.11

Although the author does not utilize these scales clinically, researchers have found them valuable for establishing standard criteria for assessing hypnotic depth.15 Ernest Hilgard has reviewed the early and more recent quantitative susceptibility scales and, together with his wife, Josephine, has devised a series of scales with much practical value for the clinician. This series has been named the Stanford Hypnotic Clinical Scales (SHCS). Some of these score the effectiveness of posthypnotic suggestion, amnesia, age regression, and special abilities, such as the availability of imagery conditions. The interested reader is referred to the exhaustive studies of the Hilgards in these areas.8

The Harvard Group Scale and the Stanford Hypnotic Susceptibility Scales are the tests most widely used by experimenters. For details, the reader is referred to the original descriptions, the items to look for, and their correlation with the responses.


1. Barber, T.X., and Calverly, D.S.: “Hypnotic behavior” as a function of task motivation. J. Psychol., 54:363, 1962.

2. Barber, T.X., and Glass, L.B.: Significant factors in hypnotic behavior. J. Abnorm. Social Psychol., 64:222, 1962.

3. Crasilneck, H.B., and Hall, J.A.: Clinical Hypnosis: Principles and Applications. New York, Grune & Stratton, 1975.

4. Davis, L.S., and Husband, R.W.: A study of hypnotic susceptibility in relation to personality traits. J. Abnorm. Social Psychol., 26:175, 1931.

5. Evans, F.J.: Recent trends in experimental hypnosis. Behav. Sci., 13:477, 1968.

6. Friedlander, J.W., and Sarbin, T.R.: The depth of hypnosis. J. Abnorm. Social Psychol., 33:453, 1938.

7. Hilgard, E.R.: Hypnotic Susceptibility. New York, Harcourt, Brace & World, 1965.

8. Hilgard, E.R., and Hilgard, J.R.: Hypnosis in the Relief of Pain. Los Altos, Cal., William Kaufman, 1976, pp. 209-221.

9. LeCron, L.M., and Bordeaux, J.: Hypnotism Today. New York, Grune & Stratton, 1947.

10. London, P.: The Children's Hypnotic Susceptibility Scale. Palo Alto, Cal., Consulting Psychologists Press, 1963.

11. Peters, J.E.: A factor analytic investigation of the Harvard group scale of hypnotic susceptibility, form A. Int. J. Clin. Exp. Hypn., 22:377, 1974.

12. Ruch, J.C., et al.: Measuring hypnotic responsiveness: a comparison of the Barber Scale and the Stanford Hypnotic Susceptibility Scale, form A. Int. J. Clin. Exp. Hypn., 22:365, 376, 1974.

13. Shor, R.E., and Orne, E.C.: The Harvard Group Scale of Hypnotic Susceptibility, Form A. Palo Alto, Cal., Consulting Psychologists Press, 1962.

14. Spiegel, H.: Eye-roll Levitation Method. Manual For Hypnotic Induction Profile. New York, Soni Media, 1974.

15. Tart, C.T.: Self-report scales of hypnotic depth. Int. J. Clin. Exp. Hypn., 18:105, 1970.

16. Weitzenhoffer, A.M., and Hilgard, E.R.: Stanford Hypnotic Susceptibility Scale, Forms A and B. Palo Alto, Cal., Consulting Psychologists Press, 1959.

17. _________: Stanford Hypnotic Susceptibility Scale, Form C. Palo Alto, Cal., Consulting Psychologists Press, 1962.

18. _________: Stanford Profile Scale of Hypnotic Susceptibility, Forms I and II. Palo Alto, Cal., Consulting Psychologists Press, 1963.

19. White, R.W.: The physical and mental traits of individuals susceptible to hypnosis. J. Abnorm. Social Psychol., 25:293, 1930.

20. Zikmund, V.: Some physiological characteristics of natural and hypnotic sleep in man. Physiol. Bahemoslav, 13:196, 1964.

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