Individual Differences

The Abbe Faria, another follower of Mesmer, recognized individual differences in response to animal magnetism as early as 1819, and there are large individual differences in response to hypnosis as well. Hypnosis has little to do with the hypnotist's technique and very much to do with the subject's capacity, or talent, for experiencing hypnosis. Hypnotizability is measured by standardized psychological tests such as the Stanford Hypnotic Susceptibility Scale or the Harvard Group Scale of Hypnotic Susceptibility. These instruments are work samples, analogous to other performance tests. They begin with a hypnotic induction in which the subjects are asked to focus their eyes on a fixation point, relax, and concentrate on the voice of the hypnotist (although suggestions for relaxation are generally part of the hypnotic induction procedure, people can respond positively to hypnotic suggestions while engaged in vigorous physical activity). The hypnotist then gives suggestions for further relaxation, focused attention, and eye closure. After the subjects close their eyes, they receive further suggestions for various imaginative experiences. For example, they may be told to extend their arms and imagine a heavy object pushing their hands and arms down, or that a voice is asking them questions over a loudspeaker, or that when they open their eyes they will not be able to see an object placed in front of them. Posthypnotic suggestions may also be given for responses to be executed after hypnosis has been terminated, including posthypnotic amnesia, the inability to remember events and experiences which transpired during hypnosis. Response to each of these suggestions is scored in terms of objective behavioral criteria—do the subjects' arms drop a specified distance over a period of time, do they answer questions realistically, do they deny seeing the object, and so on.

Hypnotizability, so measured, yields a roughly normal (i.e., bell-shaped) distribution of scores. Most people are at least moderately responsive to hypnotic suggestions, while relatively few people are refractory to hypnosis and relatively few (so-called hypnotic virtuosos) fall within the highest level of responsiveness. Cross-sectional studies of different age groups show a developmental curve, with very young children relatively unresponsive to hypnosis and hypnotizability reaching a peak at about the onset of adolescence; scores drop off among middle-aged and elderly individuals. Hypnotizability assessed in college students remains about as stable as IQ over a period of 25 years.

Although hypnotizability is generally assessed in terms of a single-sum score, factor-analytic studies reveal a degree of multidimensionality. Hypnotic suggestions can be classified roughly as ideomotor (involving the facilitation of motor responses), challenge (involving the inhibition of motor responses), and cognitive (involving alterations in perception and memory). These factors are themselves intercorrelated, so that a general dimension of hypnotizability emerges at a higher level, much like Thurstone's solution to the structure of intelligence in terms of primary mental abilities and a superordinate general intelligence.

Even though hypnosis is a product of suggestion, it is a mistake to identify hypnotizability with suggestibility. In fact, suggestibility itself is also factorially complex. Eysenck distinguished among primary (e.g., direct suggestions for the facilitation and inhibition of motor activity), secondary (implied suggestions for sensory - perceptual changes), and tertiary (e.g., attitude changes resulting from persuasive communications) forms of suggestibility; a further form of suggestibility is the placebo response. Hypnotizability is correlated only with primary suggestibility, and this is carried mostly by the relation between primary suggestibility and the ideomotor and challenge components of hypnotizability.

There is some controversy over whether hypnotiz-ability can be modified. Some clinical practitioners, influenced by the theories of Milton Erickson, believe that virtually everyone can be hypnotized, if only the hypnotist takes the right approach, but there is little evidence favoring this point of view. Similarly, some researchers believe that hypnotizability can be enhanced by developing positive attitudes, motivations, and expectancies concerning hypnosis, but there is also evidence that such enhancements are heavily laced with compliance. As with any other skilled performance, hypnotic response is probably a matter of both aptitude and attitude: negative attitudes, motivations, and expectancies can interfere with performance, but positive ones are not by themselves sufficient to create hypnotic virtuosity.

The role of individual differences makes it clear that

Hypnosis and the Psychological Unconscious in an important sense, all hypnosis is self-hypnosis. The hypnotist does not hypnotize the subject. Rather, the hypnotist serves as a sort of coach, or tutor, whose job is to help the subject become hypnotized. Although it takes considerable training and expertise to use hypnosis appropriately in clinical practice, it takes very little skill to be a hypnotist. Beyond the hypnotist's ability to develop rapport with the subject, the most important factor determining hypnotic response is the hypnotizability of the individual subject.


Hypnotizability is not substantially correlated with most other individual differences in ability or personality, such as intelligence or adjustment. Interestingly, it does not appear to be correlated with individual differences in conformity, persuasibility, or response to other forms of social influence. However, in the early 1960s, Ronald Shor, Arvid As, and others found that hypnotizability was correlated with subjects' tendency to have hypnosis-like experiences outside of formal hypnotic settings, and an extensive interview study by Josephine Hilgard showed that hypnotizable subjects displayed a high level of imaginative involvement in domains such as reading and drama. In 1974, Auke Tellegen and Gilbert Atkinson developed a scale of absorption to measure the disposition to have subjective experiences characterized by the full engagement of attention (narrowed or expanded) and blurred boundaries between self and object. Absorption is the most reliable correlate of hypnotizability (by contrast, vividness of mental imagery is essentially uncorrelated with hypnosis), although the statistical relation is too weak to permit confident prediction of an individual's actual response to hypnotic suggestion. So far as the measurement of hypnotizability is concerned, there is no substitute for performance-based measures such as the Stanford and Harvard scales.

Absorption seems to be a heretofore unappreciated aspect of individual differences. The scales of the Minnesota Multiphasic Personality Inventory, California Psychological Inventory, and other such instruments do not contain items related to absorption, which may explain their failure to correlate with hypnotiza-bility. However, absorption is not wholly unrelated to other individual differences in personality. Recent multivariate research has settled on five major di mensions—the Big Five —which provide a convenient summary of personality structure: neuroticism (emotional stability), extraversion, agreeableness, conscientiousness, and a fifth factor often called openness to experience. Absorption is correlated with openness.

Actually, the definition of the fifth factor as openness is somewhat controversial, with some theorists arguing for alternative interpretations in terms of intel-lectance (i.e., the appearance of being intelligent) or culturedness. Openness itself proves to be heterogeneous: some facets (richness of fantasy life, aesthetic sensitivity, and awareness of inner feelings) resemble absorption, while others (need for variety in actions, interest in ideas, and liberal value systems) relate to sociopolitical liberalism. In fact, hypnotizability is correlated with the absorption component of openness, but not with liberalism or intellectance. This pattern of differential correlates indicates that intellectance, absorption, and liberalism are different dimensions of personality and should not be lumped together. In stimulating the discovery of absorption, and in clarifying the nature of the fifth factor in the Big Five structure, research on individual differences in hypnotiza-bility has contributed to understanding in the broader domain of personality.

Researchers have been interested in biological correlates of hypnotizability as well as in those which can be measured by paper-and-pencil tests. Although hypnosis is commonly induced with suggestions for relaxation and even sleep, the brain activity in hypnosis more closely resembles that of a person who is awake. The discovery of hemispheric specialization, with the left hemisphere geared to analytic and the right hemisphere to nonanalytic tasks, led to the speculation that hypnotic response is somehow mediated by right-hemisphere activity. Studies that used both behavioral and electrophysiological paradigms have been interpreted as indicating increased activation of the right hemisphere among highly hypnotizable individuals, but positive results have proved difficult to replicate and interpretation of these findings remains controversial.

It should be noted that hypnosis is mediated by verbal suggestions, which must be interpreted by the subject in the course of responding. Thus, the role of the left hemisphere should not be minimized. One interesting proposal is that hypnotizable individuals show greater flexibility in deploying the left and right hemi

Hypnosis and the Psychological Unconscious spheres in a task-appropriate manner, especially when they are actually hypnotized. Because involuntariness is so central to the experience of hypnosis, it has also been suggested that the frontal lobes (which organize intentional action) may play a special role. A better understanding of the neural substrates of hypnosis awaits studies of neurological patients with focalized brain lesions, as well as brain-imaging studies (e.g., positron-emission tomography, magnetic resonance imaging) of normal subjects. [See Brain Scanning/ Neuroimaging.]

Hypnotherapy Healing

Hypnotherapy Healing

Loosely explained, hypnotherapy is an exercise of therapy which induces a deep relaxation state of body and mind and then uses this state of mind to introduce ideas or images into the consciousness.

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