Imaginative suggestibility and hypnotizability: an empirical analysis.

Hypnotic and nonhypnotic suggestibility were investigated in 2 experiments. In Experiment 1, nonhypnotic suggestibility was suppressed when measured after hypnotic suggestibility, whereas hypnotic suggestibility was not affected by the order of assessment. Experiment 2 confirmed a small but significant effect of hypnosis on suggestibility when nonhypnotic suggestibility was measured first. Nonhypnotic suggestibility was correlated with absorption, fantasy proneness, motivation, and response expectancy, but only expectancy predicted suggestibility when the other variables were controlled. Behavioral response to hypnosis was predicted by nonhypnotic suggestibility, motivation, and expectancy in a model accounting for 53% of the variance. Experiential response to hypnotic suggestion was predicted only by nonhypnotic suggestibility. Unexpectedly, hypnosis was found to decrease suggestibility for a substantial minority of participants.     

Expert judgments of hypnosis from subjective state reports.

Suggestibility was assessed in 60 college students after a traditional hypnotic induction, an alert induction, progressive relaxation training, or instruction in goal-directed imagery. Responsiveness to suggestion did not differ between groups. Subjects also generated open-ended reports of their states of awareness and of their experience of 3 hypnotic suggestions. A sample of these reports from 24 moderately to highly suggestible subjects were evaluated by 18 experts in the field of hypnosis. Expert ratings of subjects' open-ended reports indicated that (a) traditional hypnotic inductions produce a state of consciousness that is indistinguishable from nonhypnotic relaxation training, (b) the subjective experience of hypnotic suggestions after imagination training is indistinguishable from that after hypnotic inductions, and (c) suggestibility is unrelated to state of consciousness as assessed by experts.     

Hypnotic enhancement of cognitive-behavioral interventions for pain: an analogue treatment study.

Recent meta-analyses have shown that adding hypnosis enhances the effectiveness of cognitive-behavioral psychotherapy. This hypnotic enhancement effect was evaluated in the analogue treatment of pain. Individuals scoring in the high (n = 135) and low (n = 150) ranges of hypnotic suggestibility were randomly assigned to 1 of 6 conditions: Stress Inoculation Training, the same treatment provided hypnotically, nonhypnotic analgesia suggestions, hypnotic analgesia suggestions, a hypnotic induction treatment, or a control condition. The 5 analogue treatments reduced experimental pain more than the control condition, but were not different from one another. Under circumstances optimized to detect an enhancement effect, neither Stress Inoculation Training nor analgesia suggestions produced more relief when delivered in a hypnotic context than identical treatments provided nonhypnotically.     

Complexity and measurement of hypnotic susceptibility: a comment on Coe and Sarbin's alternative interpretation.

Coe and Sarbin's claim that a single role skill dimension accounts for individual differences in hypnotizability is not supported by an empirical analysis. We suggest that current measures of hypnotic susceptibility are not only factorially complex but contain a sizable nonhypnotic variance component. Implications for the assessment of "true" hypnotic susceptibility are discussed.     

Differential patterns of spontaneous experiential response to a hypnotic induction: A latent profile analysis

A hypnotic induction produces different patterns of spontaneous experiences across individuals. The magnitude and characteristics of these responses covary moderately with hypnotic suggestibility, but also differ within levels of hypnotic suggestibility. This study sought to identify discrete phenomenological profiles in response to a hypnotic induction and assess whether experiential variability among highly suggestible individuals matches the phenomenological profiles predicted by dissociative typological models of high hypnotic suggestibility. Phenomenological state scores indexed in reference to a resting epoch during hypnosis were submitted to a latent profile analysis. The profiles in the derived four-class solution differed in multiple experiential dimensions and hypnotic suggestibility. Highly suggestible individuals were distributed across two classes that exhibited response patterns suggesting an inward attention subtype and a dissociative subtype. These results provide support for dissociative typological models of high hypnotic suggestibility and indicate that highly suggestible individuals do not display a uniform response to a hypnotic induction.     

Methodological and practical issues regarding phenomenological subtypes of highly suggestible individuals: A response to Kumar

A hypnotic induction produces different patterns of spontaneous experiences across individuals. The magnitude and characteristics of these responses covary moderately with hypnotic suggestibility, but also differ within levels of hypnotic suggestibility. This study sought to identify discrete phenomenological profiles in response to a hypnotic induction and assess whether experiential variability among highly suggestible individuals matches the phenomenological profiles predicted by dissociative typological models of high hypnotic suggestibility. Phenomenological state scores indexed in reference to a resting epoch during hypnosis were submitted to a latent profile analysis. The profiles in the derived four-class solution differed in multiple experiential dimensions and hypnotic suggestibility. Highly suggestible individuals were distributed across two classes that exhibited response patterns suggesting an inward attention subtype and a dissociative subtype. These results provide support for dissociative typological models of high hypnotic suggestibility and indicate that highly suggestible individuals do not display a uniform response to a hypnotic induction.     

Hypnosis,hypnotic suggestibility,memory, and involvement in films

Our research extends studies that have examined the relation between hypnotic suggestibility and experiential involvement and the role of an hypnotic induction in enhancing experiential involvement (e.g., absorption) in engaging tasks. Researchers have reported increased involvement in reading (Baum & Lynn, 1981) and music-listening (Snodgrass & Lynn, 1989) tasks during hypnosis. We predicted a similar effect for film viewing: greater experiential involvement in an emotional (The Champ) versus a non-emotional (Scenes of Toronto) film. We tested 121 participants who completed measures of absorption and trait dissociation and the Harvard Group Scale of Hypnotic Susceptibility and then viewed the two films after either an hypnotic induction or a non-hypnotic task (i.e., anagrams). Experiential involvement varied as a function of hypnotic suggestibility and film clip. Highly suggestible participants reported more state depersonalization than less suggestible participants, and depersonalization was associated with negative affect; however, we observed no significant correlation between hypnotic suggestibility and trait dissociation. Although hypnosis had no effect on memory commission or omission errors, contrary to the hypothesis that hypnosis facilitates absorption in emotionally engaging tasks, the emotional film was associated with more commission and omission errors compared with the non-emotional film.     

Does 'hypnosis' by any other name smell as sweet? The efficacy of 'hypnotic' inductions depends on the label 'hypnosis'

Hypnosis is associated with profound changes in conscious experience and is increasingly used as a cognitive tool to explore neuropsychological processes. Studies of this sort typically employ suggestions following a hypnotic induction to produce changes in perceptual experience and motor control. It is not clear, however, to what extent the induction procedure serves to facilitate suggested phenomena. This study investigated the effect on suggestibility of (a) a hypnotic induction and (b) labelling that procedure 'hypnosis.' Suggestibility of participants was tested before and after an adapted hypnotic procedure, which was either labelled as 'hypnosis' or as 'relaxation.' The hypnotic procedure produced a modest increase in suggestibility when it was called 'relaxation,' but a very significant increase if it was labelled 'hypnosis.' The results are important for both clinical and experimental applications and indicate that labelling an induction procedure 'hypnosis' is an important determinant of subsequent responses to suggestion.     

Involvement in everyday imaginative activities, attitudes toward hypnosis, and hypnotic suggestibility.

One hundred male and 83 female subjects were assessed on absorption (i.e., involvement in everyday imaginative activities), attitudes toward hypnosis, and hypnotic suggestibility. Significant positive correlations were obtained for both sexes between absorption and attitudes and between each of these variables and hypnotic suggestibility. Multiple regression analyses indicated that most of the predicted variance in hypnotic suggestibility scores was accounted for in both sexes by the absorption variable.     

Artifact and Barber's model of hypnosis: A logical-empirical analysis

Two studies examined the relevance of artifact to Barber's model of hypnosis. Study I analyzed subjects' perceptions of instructions employed by the paradigm and demonstrated strong social pressure in the model's task motivational set not present in its standard set of hypnotic induction instructions. Study II coped with the artifact by applying the standard methodology of the model but employing a set of modified hypnotic instructions equivalent in constraint to the task motivational set. Results for 88 subjects indicated a possible behavioral consequence of the artifact variable involving an interaction between type of instruction and ease of hypnotic test item; individual differences in suggestibility also appeared to discriminate conditions with respect to the artifact in question. Collectively, results indicate that the major inference drawn from the paradigm regarding the expendability of the concept of trance should be accepted with caution.     

Is hypnotic suggestibility a stable trait?

The present study examined the trait-like nature of hypnotic suggestibility by examining the stability of hypnotic responsiveness in a test-retest design in which the procedures were administered either live or by audiotape. Contrary to the idea that hypnotizability is a largely immutable, stable trait, scores on the scale of hypnotic responsiveness decreased significantly at the second session. Measures of subjective experiences and expectancies accounted for a sizable portion of the variance in hypnotic responding, both at initial test and at retest. Participants became disengaged with the hypnotic procedures at retest. Participants who received the hypnotic induction by audiotape did not differ from participants who received it live. The results are consistent with sociocognitive and altered state theories of hypnosis, and underline the important role of subjective experiences in hypnotic responding.     

Not all group hypnotic suggestibility scales are created equal: individual differences in behavioral and subjective responses

To examine the influence of hypnotic suggestibility testing as a source of individual differences in hypnotic responsiveness, we compared behavioral and subjective responses on three scales of hypnotic suggestibility: The Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS: A; Shor, R. E., Orne, E. C. (1962). Harvard Group Scale of Hypnotic Susceptibility. Berlin: Consulting Psychologists Press); the Carleton University Responsiveness to Suggestion Scale (CURSS; Spanos, N. P., Radtke, H. L., Hodgins, D. C., Stam, H. J., Bertrand, L. D. (1983b). The Carleton University Responsiveness to Suggestion Scale: Normative data and psychometric properties. Psychological Reports, 53, 523-535); and the Group Scale of Hypnotic Ability (GSHA; Hawkins, R., Wenzel, L. (1999). The Group Scale of Hypnotic Ability and response booklet. Australian Journal of Clinical and Experimental Hypnosis, 27, 20-31). Behavioral and subjective responses to the CURSS were significantly different than those on the HGSHS: A and GSHA. More participants were classified as "low suggestible" on the CURSS and they reported subjective experiences more similar to everyday mentation. Attitudes and expectancies of participants who received the GSHA were less predictive of responding, but rates of responding and subjective experiences were similar on the GSHA and the HGSHS: A. Discussion focuses on implications for the use of group hypnotic suggestibility scales.     

Direct verbal suggestibility: Measurement and significance

Hypnotic suggestibility is part of the wider psychological trait of direct verbal suggestibility (DVS). Historically, DVS in hypnosis has informed theories of consciousness and of conversion disorder. More recently it has served as a research tool in cognitive science and in cognitive neuroscience in particular. Here we consider DVS as a general trait, its relation to other psychological characteristics and abilities, and to the origin and treatment of clinical conditions. We then outline the distribution of DVS in the population, its measurement, relationship to other forms of suggestibility, placebo responsiveness, personal characteristics, gender, neurological processes and other factors, such as expectancy. There is currently no scale specifically designed to measure DVS outside a hypnotic context. The most commonly used and well-researched of the hypnosis-based scales, the Harvard Group Scale, is described and identified as a basis for a more broadly based measure of DVS for use in psychological research.     

Effects of suggestibility and hypnosis on accurate and distorted retrieval from memory

Research investigated the hypothesis inferred from the theorizing of Loftus that suggestibility is related to the tendency to incorporate incorrect information into memory when this information has been subtly introduced after the to-be-remembered events have occurred. Specifically, it was predicted that if level of suggestibility is theoretically relevant to subjects' acceptance of misleading information, then more subjects who are highly hypnotically suggestible than those with a low level of hypnotic suggestibility will incorporate the incorrect information into memory. Hypnotic as compared with waking instruction should enhance this distortion effect by providing a context of testing in which subjects are readily prone to respond positively to suggestions. Eight independent groups of 12 subjects were tested. Separate groups of subjects of high and low suggestibility were presented with misleading or neutral information about a wallet-snatching incident and tested for memory under either waking or hypnotic instruction. Analysis of subjects' memory distortions indicated that suggestibility plays a somewhat different role than has been argued previously. The magnitude of distortion that was observed varied according to the stimulus features that were studied, but hypnotic suggestibility was not associated with the distortion effect. Despite the fact that hypnosis did not enhance recall in any way, subjects were frequently confident that distorted memories recovered under hypnosis were accurate.     

Mechanisms of hypnotic and nonhypnotic forgetting

Subjects participated in two experimental sessions designed to study laboratory-induced amnesia, one using a standard hypnosis paradigm and one using a non-hypnotic directed-forgetting paradigm. Two independent sources of variation were derived from the hypnotic amnesia data: retrieval inhibition and inhibition release. In the nonhypnotic directed-forgetting procedure, some items were cued to be forgotten shortly after presentation and some were cued to be remembered. At test, the subjects were asked to recall both the to-be-remembered and the to-be-forgotten items. Over 39% of the variance in the recall of the to-be-forgotten items could be accounted for by the inhibition and release constructs obtained with hypnosis. These relations between the two procedures were not mediated by verbal ability or cognitive style (field independence). We concluded that the mechanisms of forgetting involved in laboratory demonstrations of hypnotic and nonhypnotic amnesia are related, and the implication is that some of them are the same, namely, retrieval inhibition and inhibition release. We also argued that the possible demand characteristics that accompany the hypnosis procedure are not apparent with the nonhypnotic procedure. Therefore, the relationships observed in the present results were taken as evidence that hypnotically induced amnesia is not entirely the result of subjects' reactions to demand characteristics.     

Impulsivity,self-control,and hypnotic suggestibility

Hypnotic responding might be due to attenuated frontal lobe functioning after the hypnotic induction. Little is known about whether personality traits linked with frontal functioning are associated with responsiveness to hypnotic suggestions. We assessed whether hypnotic suggestibility is related to the traits of self-control and impulsivity in 154 participants who completed the Brief Self-Control Scale, the Self-Regulation Scale, the Barratt Impulsiveness Scale (BIS-11), and the Harvard Group Scale of Hypnotic Susceptibility (HGSHS:A). BIS-11 non-planning impulsivity correlated positively with HGSHS:A (Bonferroni-corrected). Furthermore, in the best model emerging from a stepwise multiple regression, both non-planning impulsivity and self-control positively predicted hypnotic suggestibility, and there was an interaction of BIS-11 motor impulsivity with gender. For men only, motor impulsivity tended to predict hypnotic suggestibility. Hypnotic suggestibility is associated with personality traits linked with frontal functioning, and hypnotic responding in men and women might differ.     

The role of compliance in hypnotic and nonhypnotic analgesia

We modified the standard procedure for administering finger pressure pain in order to assess the extent to which subjects biased their reports of pain reduction when exposed to compliance-inducing instructions. Experiment 1 used only highly hypnotizable subjects and found that compliance-induced reductions in reported pain were about half as large as the reported reductions produced by hypnotic analgesia suggestions. Experiment 2 used low as well as high hypnotizables and administered hypnotic or nonhypnotic analgesia instructions and compliance instructions to the same subjects on separate pain trials. Reported pain reductions produced by hypnotic and nonhypnotic analgesia suggestions and those produced by compliance instructions were substantially and significantly correlated. Furthermore, hypnotizability correlated with compliance-induced reported pain reductions as highly as it correlated with the reported reductions produced by hypnotic analgesia suggestions. Among high hypnotizables (but not low hypnotizables) compliant responding was predicted by social desirability. The findings of both studies indicate that compliance strongly influences the reports of hypnotic and nonhypnotic analgesia proffered by high hypnotizables. The role of compliance in the pain reductions reported by low hypnotizables is less clear-cut.     

Effects of instructional set on attributions of nonvolition during hypnotic and nonhypnotic analgesia

Fifty highly hypnotizable subjects were assigned to four treatment groups or a no-treatment control group and then underwent two pain stimulation trials. Half the treated subjects were administered hypnotic analgesia, half waking analgesia. Within hypnotic and nonhypnotic treatments, half the subjects were given actively worded analgesia instructions, half passively worded instructions. Subjects in the four treated groups reported equivalent pain reduction and equivalent use of coping imagery, although hypnotic subjects rated themselves as more deeply hypnotized than did nonhypnotic subjects. Both hypnotic and nonhypnotic subjects given passive instructions rated their pain reduction as occurring involuntarily, whereas those given active instructions reported that their pain was reduced through their active use of coping strategies. These findings support sociocognitive formulations of hypnotic responding that view ratings of involuntariness as reflecting contextually guided interpretations of behavior.     

Using an Individual Differences Approach to Examine Two Distinct Types of Suggestibility Effects

Two studies were conducted to examine relations between suggestibility effects studied in two commonly used research paradigms and a group of individual difference factors that have been theoretically linked to eyewitness suggestibility. In Study 1, we examined relations between the immediate acceptance of misinformation as measured by errors on misleading questions and individual differences in conformity, agreeableness, imagery ability, and memory. As predicted, the immediate acceptance of misinformation was associated with conformity but was not related to imagery ability. In Study 2, we examined relations between delayed retrieval errors produced during a classic misinformation paradigm and the same set of individual difference factors. Consistent with our predictions, delayed misinformation retrieval errors were related to imagery ability but were not related to conformity or agreeableness. Taken together, this predicted pattern of results across the two studies provides some preliminary evidence for an emerging distinction between these two types of suggestibility effects. Underlying theoretical, methodological, and practical issues related to the assessment of suggestibility effects are discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Discrete response patterns in the upper range of hypnotic suggestibility: A latent profile analysis

High hypnotic suggestibility is a heterogeneous condition and there is accumulating evidence that highly suggestible individuals may be comprised of discrete subtypes with dissimilar cognitive and phenomenological profiles. This study applied latent profile analysis to response patterns on a diverse battery of difficult hypnotic suggestions in a sample of individuals in the upper range of hypnotic suggestibility. Comparisons among models indicated that a four-class model was optimal. One class was comprised of very highly suggestible (virtuoso) participants, two classes included highly suggestible participants who were alternately more responsive to inhibitory cognitive suggestions or posthypnotic amnesia suggestions, and the fourth class consisted primarily of medium suggestible participants. These results indicate that there are discrete response profiles in high hypnotic suggestibility. They further provide a number of insights regarding the optimization of hypnotic suggestibility measurement and have implications for the instrumental use of hypnosis for the modeling of different psychological conditions.