The Maudsley Personality Inventory was administered to 349 male college students. 9 male Ss were chosen to represent each of the 4 possible combinations (total N = 36) of extreme high and low extraversion and introversion scores. An attempt was made to hypnotize each S by means of the Stanford Hypnotic Susceptibility Scale, Form C. Analysis of variance indicated no significant relationship between either extraversion or neuroticism and hypnotizability, although the relationship between extraversion and hypnotizability approached significance. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Evans, Frederick J.; Schmeidler, D. (1964). Reliability of two observers scoring the Stanford Hypnotic Susceptibility Scale, Form C. International Journal of Clinical and Experimental Hypnosis, 12 (4), 239-251.

2 Os scored the responses of 60 Ss on a 12-item objective test, Stanford Scale of Hypnotic Susceptibility, Form C (Weitzenhoffer & Hilgard, 1962). Mean total scores reported by the 2 Es did not differ significantly. The correlation between the total scores of the 2 Es was .947. Nevertheless, differences in total scores assigned occurred with 40% of Ss, which is a significant departure from perfect agreement. The 2 Es disagreed about correct scoring of 54 items (7.5% of all items scored). The extent of disagreement was significantly greater than 0. Disagreement was not related to the level of susceptibility of Ss, nor to the relative experience of Es with hypnosis. More than 1/2 of the disagreements involved systematic differences in the interpretation and application of the scoring criteria for 2 items; item 6: Dream, and item 9: Anosmia to Ammonia. These systematic differences affecting scoring reliability happened to counterbalance to produce similar total scores in this study. Several sources of potential scoring unreliability of SHSS:C are discussed. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Furneaux, W. D. (1964). The heat-illusion test and the structure of suggestibility. International Journal of Clinical and Experimental Hypnosis, 12 (3), 169-180.

2 similar forms of the heat-illusion test are shown to correlate to a smaller degree than would be expected if they measure the same attribute. The 2 versions also differ in the way in which they correlate with other suggestibility tests. It is shown that linear regression techniques are not appropriate for analyzing the data concerned. The interaction of various nonlinear relationships with a difference in “difficulty,” as between the 2 forms of the illusion, seems to provide an adequate explanation for the results. It is suggested that these nonlinear relationships may indicate the existence of an attribute which prevents some Ss from responding to any suggestibility test, irrespective of what the specific mechanisms of response may be. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Bentler, P. M.; Hilgard, Ernest R. (1963). A comparison of group and individual induction of hypnosis with self-scoring and observer-scoring. International Journal of Clinical and Experimental Hypnosis, 11, 49-54. (Abstracted in Index Medicus, 63, June, S-1599)

45 volunteer Ss were hypnotized in small groups and were subsequently hypnotized in individual sessions. In both sessions observer- and self-scores
were recorded for all suggestions of the Harvard Group Scale adaptation of the Stanford Hypnotic Susceptibility Scale. The correlation between observer- and self-scores indicated that hypnotic susceptibility in the 2 sessions was very similar. Group self-scores were also found to predict quite accurately objective hypnotist scores of the subsequent individual session. A 2nd sample of 34 nonvolunteer male Ss were hypnotized individually following Form A of the Stanford scale. Self-scoring was found to be remarkably similar to observer ratings, and the results of group administration very comparable to those of individual administration of hypnotic susceptibility tests. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Dittborn, Julio M.; Munoz, L.; Aristeguita, A. (1963). Facilitation of suggested sleep after repeated performances of the sleep suggestibility test. International Journal of Clinical and Experimental Hypnosis, 11, 236-240.

The sleep suggestibility test (SST) was individually administered to a group of young volunteer soldiers. There was increased susceptibility with each successive SST administration. It was possible to transform suggested sleep into somnambulistic hypnosis in a majority of Ss. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Evans, Frederick J. (1963). The Maudsley Personality Inventory, suggestibility and hypnosis. International Journal of Clinical and Experimental Hypnosis, 11, 187-200.

An attempt to replicate the claim of Furneaux and Gibson (1961) that stable extraverts and neurotic introverts were more susceptible to hypnotic suggestion than neurotic extraverts and stable introverts, using the MPI dimensions, was unsuccessful. Some “trends” are discussed. (PsycINFO Database Record (c) 2002 APA, all rights reserved)


Holroyd, Jean (1995). Handbook of clinical hypnosis, by Judith W. Rhue, Steven Jay Lynn, & Irving Kirsch (Eds.) [Review]. International Journal of Clinical and Experimental Hypnosis, 43 (4), 401-403.

“This is a book for the thinking clinician” (p. 401). “The editors are to be congratulated for making this volume much more coherent than most edited books” (p. 402). “My impression is that the book is best suited for an intermediate or advanced course on hypnotherapy, or for people who are already using hypnosis in treatment. Although there is some material on the basics of hypnotic inductions and a few introductory sample scripts for inductions, a beginners” course should probably use a different book, or this book could be accompanied by an inductions manual. … I recommend it very highly” (p. 403).

Zilbergeld, Bernie; Edelstien, M. Gerald; Araoz, Daniel L. (1986). Hypnosis – Questions & Answers. New York NY: Penguin Books.

The editors requested experts in hypnosis to answer common questions that resulted from qustionnaires given to over 600 health professionals who had taken a course in hypnosis during the previous three years, as well as a few questions suggested by colleagues. “We do not view this book as providing right answers, but instead as something clinicians can turn to when they have questions or want to learn how a recognized authority handles a particular issue. There are, in fact, no right answers, no one-and-only best way” (p. xviii).


Freeman, Robert; Barabasz, Arreed; Barabasz, Marianne (2000). Hypnosis and distraction differ in their effects on cold pressor pain. American Journal of Clinical Hypnosis, 43 (2), 137-148.

This study sought to determine whether highly hypnotizable Ss differ from low hypnotizables in perceived pain and neocortical electrical activity in 3 conditions. On the bases of E. R. Hilgard”s neo-dissociation theory (1977) and N. P. Spano”s (1982) sociocognitive theory, Ss selected for high and low hypnotizability (10 in each group) were exposed to a cold pressor pain test during counterbalanced conditions of waking relaxation, distraction, and hypnosis. To better discriminate between hypnosis and distraction conditions, a new distraction procedure was developed involving the memorization of a sequence of colored lights. High hypnotizables showed significantly greater pain relief for hypnosis vs distraction or waking relaxation conditions. They also demonstrated significantly greater pain relief than low hypnotizables in response to hypnosis. Electroencephalographic findings showed significantly greater high theta (5.5-7.5 Hz) activity for highs as compared to lows at parietal (P3) and occipital (01) sites during both hypnosis and waking relaxation conditions. The findings fail to support the sociocognitive conceptualization of hypnotic behavior but provide evidence supporting the neo-dissociation theory and state based theories of hypnosis. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Montgomery, Doil D.; Dwyer, Kimberly V.; Kelly, Shannon M. (2000). Relationship between QEEG relative power and hypnotic susceptibility. American Journal of Clinical Hypnosis, 43 (1), 71-75.

Investigated the relationship between quantitative electroencephalograph relative amplitude, relative power and hypnotic susceptibility. Ss were 41 adults (aged 22-40 yrs). Hypnotic susceptibility, measured by the Wickramasekera Experience Inventory, was found to be positively correlated with QEEG theta relative amplitude. In addition, hypnotic susceptibility was found to be negatively correlated with QEEG alpha relative amplitude and alpha relative power. These findings suggest that QEEG relative amplitude and QEEG relative power, as correlates of hypnotic susceptibility, may be a promising avenue for future research. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

Anderson, Kathryn (1999, November). A test of Barabasz’ alert hypnosis on EEG Beta and Theta production for children with ADHD. [Paper] Presented at Annual Meeting of the Society for Clinical and Experimental Hypnosis, New Orleans, LA.

This study tested the effects of Barabasz”s Instant Alert Hypnosis (IAH), also known as Instantaneous Neuronal Activation Procedure (INAP, Barabasz and Barabasz, 1995) used as an adjunct to neurotherapy. The sixteen children who participated in ths study met DSM – IV criteria for attention deficit hyperactivity disorder (AD/HD). Trials of neurotherapy alone were compared to neurotherapy combined with alert hypnosis on beta-theta ratios at five electrode sites (Fp1, Fp2, Fz, Cz and Pz). The results showed that EEG beta-theta ratio means were significantly higher (more than twice as large) in the trials of neurotherapy combined with alert hypnosis in contrast to neurotherapy alone. Beta was significantly enhanced while theta was inhibited. The clinical implications of these findings with regard to improved treatment efficacy and reduced time in treatment are discussed. [Abstract taken from SCEH “FOCUS”, Winter 2001..]“

Nishith, Pallavi; Barabasz, Arreed; Barabasz, Marianne; Warner, Dennis (1999). Brief hypnosis substitutes for alprazolam use in college students: Transient experiences and quantitative EEG responses. American Journal of Clinical Hypnosis, 41 (3), 262-268.

We sought to determine: 1) whether a simple hypnotic induction with an alprazolam experience derived suggestion could recreate the subjective effects of alprazolam (Xanax), 2) whether the effects of alprazolam are greater than the effects of hypnosis plus this suggestion, and 3) whether the effects of hypnosis plus this suggestion were greater than the relaxation effects produced by hypnosis alone. High and low hypnotizable student volunteer subjects (Ss) ingested 1 mg of alprazolam. A hypnotic suggestion was developed on the basis of their reported reactions to alprazolam. Four days later the same Ss were exposed to hypnosis only and hypnosis plus the alprazolam experience based suggestion conditions in counterbalanced order. Ss exposed to the hypnosis plus suggestion condition demonstrated greater levels of relaxation as measured by the tension-anxiety scale of the Profile of Mood States (POMS) (Eichman & Umstead, 1971) than in the alprazolam condition or the hypnosis only condition. High hypnotizables showed significantly greater levels of relaxation than the low hypnotizables in each of the three conditions (hypnosis plus suggestion, hypnosis only, alprazolam only). EEG data showed frontal and occipital sites were specifically involved in both the alprazolam and the hypnotic suggestion conditions. The findings indicate a basis for the use of hypnosis as a substitute for sedative drug use. Limitations and implications for clinicians are discussed.

Ray, William J. (1997). EEG concomitants of hypnotic susceptibility. International Journal of Clinical and Experimental Hypnosis, 45 (3), 301-313.

Numerous historical attempts have been directed at understanding electrocortical concomitants of hypnosis. Today, with the availability of more sophisticated multichannel recording technologies and signal-processing approaches, it is possible to reconsider and update previous attempts. The most solid relationship between electrocortical activity and hypnotizability exists in the EEG theta frequency range. Given the stable electrocortical differences found in high and low susceptible individuals, the question arises whether we can use additional EEG measures to help understand the nature of these individual differences. One possible alternative is the pointwise or fractal dimension, which we examined during baseline conditions with high and low hypnotic susceptible individuals. The dimensionality measures suggest that high susceptible individuals display underlying brain patterns associated with imagery, whereas low susceptible individuals show patterns consistent with cognitive activity (i.e., mental math). This type of speculation is similar to that of Tellegen, who makes a distinction between imaginative versus realistic responding. Future research should address the exact nature of the underlying process (imagination, effortlessness, suggestibility, etc.) seen in high and low susceptible individuals. Journal Abstract.

Graffin, Nancy F.; Ray, William J.; Lundy, Richard (1995). EEG concomitants of hypnosis and hypnotic susceptibility. Journal of Abnormal Psychology, 104, 123-131.

Electroencephalograph (EEG) measures described high- and low-hypnotizable participants in terms of 3 conditions: an initial baseline period; baselines preceding and following a standard hypnotic induction; and during the induction. The following results were obtained. 1. High and low-hypnotic susceptible participants displayed a differential pattern of EEG activity during the baseline period, characterized by greater theta power in the more frontal areas of the cortex for the high-susceptible participants. 2. In the period preceding and following a standardized hypnotic induction, low-susceptible participant displayed an increase in theta activity, whereas high-susceptible participants displayed a decrease. 3. During the actual hypnotic induction itself, theta power significantly increased for both groups in the more posterior areas of the cortex, whereas alpha activity increased across all sites. Implications of these data include the possibility of psychophysiological measures offering a stable marker for hypnotizability, and anterior/posterior cortical differences being more important than hemispheric foci for understanding hypnotic processes.

7970, Lynn & Nash, 1994 ABSTRACT: In this article we address a number of issues relevant to the practice of psychotherapy and hypnotherapy: How reliable is memory? How are therapists’ and clients’ beliefs and expectancies related to pseudomemory formation? Are certain clients particularly vulnerable to pseudomemory creation? Does hypnosis pose special hazards for pseudomemory reports? What are the variables or factors that mediate hypnotic pseudomemories? In addition to reviewing the literature on these topics, we intend to sensitize the clinician to the potential pitfalls of critical reliance on the patient’s memories, as well as uncritically accepted clinical beliefs and practices.

Ray, William J. (1995, November). EEG signatures of hypnotic susceptibility and hypnosis: It’s what’s up front that matters. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Antonio, TX.

We have done three studies: a psychometric study, one in which we used traditional ways of looking at EEG, and more recent research.
Study I found that hypnotizability related to absorption, but not to tests of absent mindedness/cognitive failures, abuse/neglect, attachment, depression and anxiety, NEO Five Factor Test scales (Neuroticism, Extroversion, Openness to Experience, Agreeableness, and Conscientiousness) or the Marlow Crown Social Desirability Scale. Also there was no relationship to Bernstein and Putnam’s measure of dissociation, the DES. There is a hint of a relationship to the Openness Scale, actually.
Study II included a literature review on 3 questions: 1. Are there differential electrocortical differences between high and low susceptible individuals? 2. Are there electrocortical markers for the hypnotic state itself? 3. Are electrocortical differences found in the trance state mediated by hypnotic procedures?
Results of Study II are published in Graffin, Ray, & Lundy, 1995.
Study III investigated three questions: 1. Are there initial baseline psychophysiological differences between High and Low susceptible Ss? 2. Are there psychophysiological differences in baseline? 3. Are there behavioral differences on the challenge tasks during the Stanford-C?
The Pre-induction baseline followed by post-induction baseline are reported today. (They also administered tasks, not discussed here.)
Literature indicates that EEG theta is much higher for highs than lows, especially in frontal and temporal areas. This is a stable finding in a number of studies. There are also posterior differences, but they are not as significant. The differences in theta between highs and lows remains across different tasks (like imaging, spatial rotations, math). Whatever differences in theta exist when high and low hypnotizable subjects walk into the room, continue across tasks. The difference also is observable in alpha.
In the whole study we found no alpha differences and no hemisphere differences, but we did find theta differences.
We thought there would be less dimensionality as someone enters hypnosis. Dimensionality reflects EEG wave form (e.g. a sine wave is simple; more complex wave is multidimensional) and is analyzed with “chaos measures” [these notes may be poor regarding this issue]. But we didn’t find less dimensionality as people entered hypnosis. So if dimensionality reflects brain state maybe people don’t change state as they enter hypnosis.
Highs do show higher dimensionality vs lows, across all brain areas. What does this mean? It’s as if Highs walk into the experiment in a more imagery mode than lows, and they continue that way throughout the whole experiment.
The differences found in baseline were all in theta. We compared the Standard Induction vs Self Induction on the EEG Theta variable: highs show more theta across the whole brain than lows, and it doesn’t matter what type of induction is used.
De Pascalis gets me thinking about the role of attention in hypnosis. Following an induction, on 35-45 Hz band of EEG there is greater frontal activity for Lows whereas for Highs you see more activity posteriorly. The difference is on the rostral-caudal dimension rather than the lateral

Crawford, Helen J. (1994). Brain dynamics and hypnosis: Attentional and disattentional processes. International Journal of Clinical and Experimental Hypnosis, 42 (3), 204-232.

This article reviews recent research findings, expanding an evolving neuropsychophysiological model of hypnosis (Crawford, 1989; Crawford & Gruzelier, 1992), that support the view that highly hypnotizable persons (highs) possess stronger attentional filtering abilities than do low hypnotizable persons, and that these differences are reflected in underlying brain dynamics. Behavioral, cognitive, and neurophysiological evidence is reviewed that suggests that highs can both better focus and sustain their attention as well as better ignore irrelevant stimuli in the environment. It is proposed that hypnosis is a state of enhanced attention that activates an interplay between cortical and subcortical brain dynamics during hypnotic phenomena, such as hypnotic analgesia. A body of research is reviewed that suggests that both attentional and disattentional processes, among others, are important in the experiencing of hypnosis and hypnotic phenomena. Findings from studies of electrocortical activity, event-related potentials, and regional cerebral blood flow during waking and hypnosis are presented to suggest that these attentional differences are reflected in underlying neurophysiological differences in the far fronto-limbic attentional system.

Freeman, R.; Barabasz, A.; Barabasz, M. (1994, October). EEG topographic differences between dissociation and distraction during cold pressor pain in high and low hypnotizables. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Francisco.

Hilgard once said we should study what is going on inside the skull when we study hypnotic behavior. Theta EEG was studied, in 3.5 and 5.5-7.5 band widths, based on Crawford’s research (no differences between high and low hypnotizables in low range but significant differences in waking state, eyes closed condition).
Also employed new type of distraction procedure. Previously used as comparison conditions things like imagine a pleasant scene, do whatever you can do to reduce pain, or imagine an instructor giving a lecture. Barabasz theorized that highs, given the opportunity, may spontaneously get involved in imagery; so distraction used in some experiments may actually become hypnosis. Here, distraction involved using a storage box, with plexiglass covering front, and 3 lights–subjects were to recall sequence of light changes that occurred during 60 sec when arm was in the cold water.
Cold pressor pain. 3 immersions with simultaneous pain reporting and EEG monitoring. –Waking State –Light array distraction –Hypnotic induction and suggested analgesia (Distraction and hypnosis with analgesia were presented in a balanced design)
Pain Ratings ranged from 0 = no pain, 10 = level would very much like to remove arm from water (rating could exceed 10 however). After removing arm, subjects were to report the maximum amount of pain that they had felt. Pain Scores were obtained at 30 seconds and 60 seconds after immersion in the cold water.
Also got qualitative data. During recovery period after each arm immersion, Subjects were asked what if anything they had done to reduce the pain felt.
30 second pain scores: Waking 7.60 vs 7.50 Distraction 8.60 vs 6.80 Hypnotic analgesia 7.80 vs 4.10 (Significantly different).
60 second pain scores: Showed same trend
There was no difference whatsoever for the lows.
Results for the 2 EEG sites: P3 left hemisphere parietal in waking and hypnotic analgesia, high theta, had significantly different activity O1 left hemisphere in waking and hypnotic analgesia, was significantly different between highs and lows (same as above).
Results for two theta ranges: Low theta range, T4 temporal right hemisphere, for lows in waking and [missed words] condition–hard to interpret this finding.
RESULTS. Highs demonstrated pain reduction in hypnotic analgesia compared to waking and distraction conditions and compared to lows. Lows had no differences in any condition.
Enhanced EEG theta in left parietal area differentiated highs and lows. This suggests that highs generate enhanced disattention that may be controlled by these areas.
P3 area regulates the integration and association of somatic perceptions. The O1 area controls processing of visual imagery. Perhaps high hypnotizables have more ability to alter afferent sensory information through focused attentional processes. Also, the ability to alter the suffering portion of pain experience may involve visual imagery activity.
State and trait differences are apparent.
The low theta range may be more closely related to slower delta range 0-3.5 that is associated with sleep and drowsiness. High theta = low arousal and attention capacity. That’s why theta seems associated with wide range of behaviors that appear contradictory
The qualitative data shows highs reported they spontaneously preferred strategies that were more than distraction (associating colors with warmth, thinking of warm water) and the most frequent responses of lows were “nothing” or “told myself it would be over soon.”
Highs in analgesia condition used no specific strategy: 8/10 reported the arm simply felt more numb.

Ray, William J.; Moraga, R.; Faith, M. (1994, October). Psychometric and psychophysiological studies of hypnotizability and dissociation. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Francisco.

In the last 5-6 years we see a beginning of a consistency in this type of research on EEG and hypnosis. Baseline EEG theta for high and low hypnotizable Ss was higher significantly in frontal and temporal areas; less significantly in parietal and occipital areas. It begins to look like a signature of hypnotizability. Our research will be published in the Journal of Abnormal Psychology next year.
In Japan they see theta as sustained attention; some aspects of theta relate to MAO and also to dopamine. Betsy Faith did the same research, replicating almost exactly.
There are no differences between Highs and Lows in alpha or beta; but we find differences in theta (especially frontal, and in 40 Hz more posteriorly). It may not be L-R hemisphere difference as previously thought, but more a rostral-caudal dimension.
The signature to hypnotizability is more frontal theta at baseline. This may also relate to a drop in theta after induction, but those results are not so clear. Highs have a larger drop in theta from pre to post induction than is observed in the Lows.
We did a “chaos analysis” of EEG. There are three main measures, including dimensionality. Dimensionality is a measure of complexity. People demonstrate high dimensionality when asked to do tasks, low dimensionality in anesthesia.
High hypnotizable Ss start an induction with higher dimensionality than the Low hypnotizable Ss, and as we go through the induction they remain the same. So this measure shows individual differences but does not give evidence of a state (because it doesn’t change).
Chaos dimensions for 2 mental math problems show lower dimensions in frontal compared to posterior areas; but for imagery [labeled on slide as positive and negative emotional tasks] the dimension is the same across areas.
For the dimension measures, lows look like they are doing mental math and highs look like they are doing imagery, in baseline.
SECOND PART OF RESEARCH–DISSOCIATION. For 100 years dissociation and hypnosis have been viewed as similar. Two dissociation scales were used – Putnam’s DES and Reilly’s scale. A factor analysis found four factors: 1. absorption or derealization 2. depersonalization 3. segment amnesia 4. in situ amnesia
(Segment amnesia differs from in situ amnesia because you wake up to it at that moment in the in situ vs the segment case.)
We have 20-30 people who score very high on hypnotizability.
Colin Ross finds the same factors as our factors 1 and 2, but he finds only one amnesia factor where we find two.
The correlation between DES and Harvard ranges .05 to .18. Are the high hypnotizables related to high dissociatives, with others not related? A scatter plot did not reveal that.
FFT EEG bands during baseline for high and low dissociation Ss find no differences for high and low dissociative subjects. We conclude that dissociation and hypnosis are two orthogonal processes.
Now we are beginning to look at the pathways that lead one to become highly hypnotizable or dissociative.
Ian Wickramasekera: Have you introduced threat to high or low DES people? Answer: High and Low DES people with happy and unhappy imagery tasks do the opposite, with the dimensionality measure. With emotionality you don’t see stable baseline differences, you see reactivity differences.
A. Barabasz: I think the DES isn’t a good measure of dissociation in hypnosis which is voluntary and not pathological.
D. Spiegel: Sabourin’s study found more theta in left frontal during hypnosis, whereas you found less. Answer: That’s why I don’t know what to do about the state effects.
J. Crawford: Sabourin had Ss doing tasks, so they may have been more active than yours.

Atkinson, Richard P.; Crawford, Helen J. (1992). Individual differences in afterimage persistence: Relationships to hypnotic susceptibility and visuospatial skills. American Journal of Psychology, 105 (4), 527-539.

To investigate the moderating role of individual differences in hypnotic susceptibility and visuospatial skills on afterimage persistence, we presented a codable (cross) flash of light to 40 men and 46 women who had been dark adapted for 20 minutes. In an unrelated classroom setting, subjects had previously been given two standardized scales of hypnotic susceptibility (Harvard Group Scale of Hypnotic Susceptibility, Shor & Orne, 1962; Group Stanford Hypnotic Susceptibility Scale, Form C, Crawford & Allen, 1982) and the Mental Rotations Test (Vandenberg & Kuse, 1978). The first afterimage interval and the afterimage duration correlated significantly with hypnotic responsiveness, supporting Wallace (1979), but did not show the anticipated relationships with mental rotation visuospatial skills. Individuals in the high hypnotizable group had (a) significantly longer afterimage intervals between its first appearance and first disappearance than did those in low groups, but those in medium groups did not differ significantly from the other groups. Discriminant analysis using the afterimage persistence measures classified correctly 65.2% of high hypnotizables, 37.5% of medium hypnotizables, and 54.8% of low hypnotizables. Hypothesized cognitive skills that assist in the maintenance of afterimages and underlie hypnotic susceptibility include abilities to maintain focused attention and resist distractions over time and to maintain vivid visual images.

DISCUSSION “Because there is no apparent evidence for physiological differences of the visual system between low and high hypnotizables (e.g., Wallace, 1979), cognitive factors are suggested as possible moderators of afterimage persistence.
“Hypnotic susceptibility per se is not the moderator of afterimage duration. Rather, we argue that hypnotic susceptibility represents a constellation of underlying cognitive skills (e.g., for reviews, see Crawford, 1989; Kihlstrom, 1985) that assist an individual to respond to hypnotic suggestions as well as assist in the persistence of afterimages by interacting with more primary casual mechanisms that are physiological in origin. These cognitive skills are thought to include the abilities to focus attention selectively upon both external stimuli and internally generated images, to maintain vivid visual images, to sustain attention over time and remain absorbed in the experience at hand, and to resist distractions. The relationships between these cognitive skills and hypnotic susceptibility are reported in a large body of literature (e.g., Crawford, 1982, 1989; Crawford et al., 1991; Crawford & Grumbles, 1988; Finke & Macdonald, 1978; Grumbles & Crawford, 1981; Mitchell, 1970; Tellegen & Atkinson, 1974)….
“Sustained and selective attention without interference from extraneous stimuli plays an important role in hypnosis. Individuals who are responsive to hypnosis demonstrate greater skills in extremely focused and sustained attention (e.g., Crawford et al., 1991; Tellegen & Atkinson, 1974). Electrophysiological research had found that high hypnotizables often generate substantially more theta electroencephalogram (EEG) power than do low hypnotizables (e.g., Crawford 1990, 1991; Crawford & Gruzelier, 1992; Sabourin, Cutcomb, Crawford, & Pribam, 1990). Such a relationship may be interpreted as further evidence of greater attentional skills in highs, because certain theta waves have been correlated with enhanced problem solving and attentional task performance (e.g., Crawford & Gruzelier, 1992; Schacter, 1977)….
“Hypnosis is seen often as a condition of amplified attention, where attention can be either more focused or diffuse dependent upon set (e.g., Krippner & Binder, 1974). Increases in vigilant performance during hypnosis have been reported, albeit inconsistently (e.g., Barabasz, 1980; Fehr & Stern, 1967; Kissen, Reifler, & Thaler, 1964; Smyth & Lowy, 1983). Fehr and Stern’s results suggest that hypnotized subjects devote more attention to a primary task with less available attentional resources for a secondary task. Hypnosis has been found to have an enhancing effect on the imaginal processing of information-to-be-remembered that consists of literal or untransformed representations of pictorial or nonverbal information for high but not low hypnotizables (Crawford & Allen, 1983; Crawford, Nomura, & Slater, 1983; Crawford, Wallace, Nomura, & Slater, 1986). This may possibly be the result of increased attention and/or shifts in cognitive strategies. Supportive of the hypothesis that sustained attention can be enhanced during hypnosis, Atkinson (1991) recently found that high but not low hypnotizables report significantly more persistent afterimages in hypnosis than in waking.
“Although we have argued for a cognitive explanation for individual differences in afterimage persistence and their possible relationship to hypnotic susceptibility and sustained attentional abilities, as has Wallace (1979, 1990), we must point out the possibility that high hypnotizables may be more suggestible to imagery instructions or more willing to discuss or experience imagery than low hypnotizables, particularly in the context of hypnosis and hypnotic susceptibility testing (e.g., Zamansky, Scharf, & Brightbill, 1964). A contextual account of the longstanding relationship between hypnotic susceptibility and absorption was raised by Council, Kirsch, and Hafner (1986), but was not supported by two independent, and more methodologically sound, studies reported by Nadon, Hoyt, Register, and Kihlstrom (1991). The context of hypnosis was not an issue in the present study, because none of the subjects was aware of the investigated relationship between afterimage persistence and hypnotic susceptibility at the time of recruitment or participation” (pp. 533-535).

Graffin, N. W. (1991, October). EEG concomitants of hypnotic susceptibility and hypnosis (Dissertation, Pennsylvania State University). Dissertation Abstracts International, 52 (4), 2296.

“Many previous studies of EEG and hypnosis were completed prior to development of spectral analysis and typically included data from a limited number of electrode sites. The categorization of subjects as high and low hypnotizables was often done inappropriately, and disparate findings were obtained. In this study, subjects scoring 10 or more and 3 or less on the Stanford Hypnotic Susceptibility Scale, Form C were defined as high and low respectively. EEG was monitored during resting baseline, mental arithmetic, and mental spatial rotation, and before, during, and after hypnotic induction. EEG was recorded monopolarly at frontal (F3,F4), parietal (P3,P4), temporal (T3,T4), and occipital (O1,O2) derivations, and data were fast Fourier analyzed. Mental arithmetic and mental spatial rotation did not produce differential hemispheric activation. High hypnotizables had greater frontal and temporal theta at baseline than lows. All subjects showed increases in parietal and occipital theta during hypnotic induction. During prehypnotic induction baseline, highs had greater parietal and occipital theta than lows, but this different was smaller after induction. Baseline temporal alpha was greater for highs than lows, but after hypnotic induction, all subjects had less alpha at all sites than before induction. Increases in alpha at all sites for all subjects occurred during hypnotic induction. Beta activity was unrelated to susceptibility but was greater in waking than in hypnotic states for all subjects at all sites. Increases in alpha at all sites for all subjects occurred during hypnotic induction. The theta activity observed suggests that high hypnotizables have a greater capacity for selective attention and imagery and that during hypnosis all subjects experience enhancement of these abilities. The alpha results may suggest an increase in the focusing of subjects on internal processes during hypnosis and greater scanning of the environment after induction” (p. 2296).

Sabourin, M. E.; Cutcomb, S. D.; Crawford, H. J.; Pribram, K. (1990). EEG correlates of hypnotic susceptibility and hypnotic trance: Spectral analysis and coherence. International Journal of Psychophysiology, 10, 125-142.

EEG was recorded during waking rest, hypnosis (rest, arm immobilization, mosquito hallucination, hypnotic dream), and waking rest. Twelve very low and 12 very highly hypnotizability subjects participated. Evaluations were fast-Fourier spectral analysis, EEG coherence between selected deviations, and maximum spectral power within EEG bands. In eyes-open and eyes-closed conditions in waking and hypnosis, highly hypnotizability subjects generated substantially more mean theta power than did low-hypnotizable subjects at all occipital, central, and frontal locations in almost all conditions of waking and hypnosis, with a larger difference in frontal locations. Both low and high hypnotizables showed increased mean theta power in hypnosis, suggesting an intensification of attentional processes and imagery enhancement. Mean alpha power was never a predictor of hypnotic susceptibility. Interactions with hypnotic susceptibility showed that highly susceptible subjects had more beta activity in the left than in the right hemisphere, whereas low-susceptible subjects showed only weak asymmetry. No main effects for or interactions between waking/hypnosis and hypnotic level were found for coherence between derivations or maximum spectral power within theta, alpha, and beta EEG bands.

Tebecis, A. K.; Provins, K. A.; Farnbach, R. W.; Pentony, P. (1975). Hypnosis and the EEG: A quantitative investigation. Journal of Nervous and Mental Disease, 161, 1-17.

A quantitative investigation of the EEG during hypnosis was made by analyzing the analogue power frequency spectrum of one group of subjects in the awake and hypnotized conditions, and another group (random sample) in the awake condition. Individuals of the first group were thoroughly experienced in self-hypnosis and highly hypnotizable, whereas those of the second group had never been hypnotized and were low in waking suggestibility. There were no statistically significant differences in mean power of the whole EEG spectrum between the awake and hypnotized conditions of the experimental group, although a trend toward increased theta (4 to 8 Hz) density during hypnosis was apparent. This group, however, exhibited significantly more theta activity during both the hypnotized and the awake conditions than the random sample of controls in the awake condition, irrespective of whether the eyes were closed or open. We suggest that this increased theta density in the EEG is related to frequent experience of self- hypnosis, high hypnotizability, or both.


Jasiukaitis, Paul; Spiegel, David (1995, November). Relateralizing hypnosis, or have we been barking up the wrong hemisphere?. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Antonio, TX.

The association between the right hemisphere and hypnotizability dates to the Gurs and Bakan; and to Hilgard and Morgan who developed a measure based on EEG power spectrum. Results from the body of research using alpha are conflicting. De Pascalis, 1988, also couldn’t show a large alpha difference between hemispheres.
Research on hypnotic hallucination with Pribram found Highs in a visual obstruction condition reduced P200 and P300; there was a slightly greater response at O2 than O1 EEG leads, leading us to think it was maybe a Right hemisphere task. But it was a foveal stimulus.
We tested with hemifield stimuli, blocking perception of 1/2 of the visual monitor; had them do the obstruction hallucination. P200 had the greatest reduction, with stimuli presented on the left. With obstruction of left visual field, we got little response. So ERP results were greater in right visual field (left hemisphere). This suggests the earlier observation was predominantly due to left, not right, hemisphere influence.
Martha Farah’s work on imagery is instructive. Also Steve Kosslyn. The Right hemisphere answers “Where” do you see something. The Left answers “What is it you see?” The left hemisphere generates image patterns that match what you see. When you ask people to generate an image, the activity is in O1 area. Also, patients with left hemisphere damage can’t generate images; callosectomy patient also gave evidence. Many inductions use generation of images (left occipital and temporal regions). So when asking subjects to generate a hallucinated image blocking the screen, they are using that area.
The cortex can serve as an amplifier or a suppressor of response. In earlier study of somatosensory potential we observed bigger response when asking person to be more aware of pain. The cortex has an arousal system. There are two relevant systems in the brain (see Posner)–posterior and anterior. Hypnotizability is correlated with a metabolite of dopamine, which is associated with the anterior system which is dopaminergic.
Tucker & Williamson, in article in Psychological Review, 1984, write that activation is “the determination of information control by previous, stored internal representations” as opposed to arousal which is the “determination by novel [missed words….]”
Kinsbourne, in Consciousness and Contemporary Science, 1988. wrote that if at any time a hemisphere works like an automaton, it is the left hemisphere. With R. Davidson, he has shown the left hemisphere elevates affect, the right depresses it. Many people report that hypnosis is a pleasurable thing to do, maybe because it elevates mood.
One obstacle to this formulation is the idea that the left hemisphere governs logical thought.
We may disturb the relationship between words and images in hypnosis; you start to manipulate images and passively receive words, so that language is now a passive, receptive experience and images are active (instead of the usual pattern of actively using words and passively using images).

Freyd, Jennifer J. (1994). Betrayal-trauma: Traumatic amnesia as an adaptive response to childhood abuse. Ethics and Behavior, 4.

Betrayal-trauma theory suggests that psychogenic amnesia is an adaptive response to childhood abuse. When a parent or other powerful figure violates a fundamental ethic of human relationships, victims may need to remain unaware of the trauma not to reduce suffering but rather to promote survival. Amnesia enables the child to maintain an attachment with a figure vital to survival, development, and thriving. Analysis of evolutionary pressures, mental modules, social cognitions, and developmental needs suggests that the degree to which the most fundamental human ethics are violated can influence the nature, form, processes, and responses to trauma.

“A logical extension of this research direction, based on a strategy that has been very effective in cognitive neuroscience, would be to look for neuroanatomical underpinnings of the cognitive mechanisms implicated in dissociation. … For instance, the ability to dissociate current experience may depend partly on representational structures that support spontaneous perceptual transformations of incoming events. One possible perceptual transformation that is amenable to scientific investigation, would be the creation of spatial representations in which the mental ‘observer’ is spatially distinct from the real body of that observer. Such a representation would fit patient descriptions of ‘leaving their body’ during a traumatic episode and viewing the scene as if from afar. Additionally one could investigate the role of mental recoding and restructuring during memory ‘recovery’ and psychotherapy” (pp. 19-20).

Balthazard, Claude G. (1993). The hypnosis scales at their centenary: Some fundamental issues still unresolved. International Journal of Clinical and Experimental Hypnosis, 41, 47-73.

Current approaches to the measurement of hypnotic performance can be traced back to the 19th century. In part because of these early origins and in part because of the nature of hypnotic phenomena, the hypnosis scales are unique psychometric instruments. The classic hypnosis scales are based on the notion of a “performance ladder”; items are scored on a pass/fail basis and can be arranged in incrasing order of difficulty. Some of the implications on [sic]this “performance ladder” approach are reviewed. The evidence for two-mechanism models of hypnotic performance is reviewed. It is argued that this kind of formulation is at least as plausible as one that argues that the hypnosis scales measure “one thing” or “mostly one thing.” If it were the case that the hypnosis scales were tapping two different and distinct processes, the label “hypnotic susceptibility” could not be unambiguously applied to scores on the hypnosis scales. The hypnosis scales would appear well-suited to the investigation of underlying mechanisms, yet no consistent picture of the mechanisms underlying hypnotic performance on the scales has emerged thus far. No resolution is presented, but some of the reasons why such a resolution is so elusive are discussed. The future of hypnosis scales is discussed with respect to multidimensional assessment and alternatives to the “work sample” approach.

Author discusses the hypnotizability scales’ history and psychometric properties, suggesting that they cannot have construct validity if more than one construct is involved. He states that many of the alternative formulations “posit structurally similar two- mechanisms models, where the relative contributions of one and the other mechanism changes gradually with the difficulty of the hypnotic performance–that is, one mechanism is more important for easy items and the other more important in the difficult range. This kind of formulation has been advanced by a number of authors ….. Although these formulations are structurally similar, the nature of the mechanisms has been variously conceptualized: nonability and ability components (Shor, Orne & O’Connell, 1962), primary suggestibility and somnambulism (Weitzenhoffer, 1962), minor and major dissociations (Hilgard, 1977), compliance and true hypnosis (Tellegen, 1978-1979), and cooperativeness and expectation at one end and absorption at the other (Spanos, Mah, Pawlak, D’Eon, & Ritchie, 1980). … In a formulation such as Hilgard’s (1977), where both mechanisms are dissociative, it may be that it makes some sense to understand both mechanisms as aspects of the same complex construct. In other formulations… it would appear more cogent to speak of two constructs. Spanos et al. (1980) found that ‘cooperativeness and expectation may be particularly important in responding to ideomotor and challenge suggestions, while the ability to convincingly treat imaginings as real (i.e., absorption) becomes increasingly important for more difficult ‘cognitive’ items” (p. 21). Balthazard & Woody (1992) presented evidence that the more difficult items on hypnotizability scales are related to absorption more than the easier items.
Balthazard & Woody (1989) investigated the proposition that hypnotizability scores are distributed bimodally, and concluded that statistical problems clouded the issue. Furthermore, most analyses previously have been of surface structure, which does not relate directly to the underlying mechanisms of hypnosis, and current psychometric methods cannot address the mechanisms that underlie surface relations. “There are two aspects of hypnotic processes … that obscure underlying mechanism: synergisms and overdetermination. Synergisms occur when mechanisms potentiate each other in such a way that a combination of processes becomes more than the sum of its parts. Overdetermination occurs when co-occurring mechanisms do not potentiate each other, such that any one of the mechanisms would have been sufficient to produce the observed effect” (p. 63-64).
The author suggests there are two options at present: Corrective Scoring (like the Curss.OI, an objective-involuntary score which, although unreliable on test-retest, appears it could be more a measure of “pure” hypnotizability) and not using the typical “work sample” approach. Balthazard and Woody (1992) suggested the Absorption Scale may provide a better measure of “hypnotizability” than the standard hypnosis scales because absorption scores are more strongly related to difficult hypnotic performances.

Balthazard, Claude G.; Woody, Erik Z. (1992). The spectral analysis of hypnotic performance with respect to ‘Absorption’. International Journal of Clinical and Experimental Hypnosis, 40, 21-43.