Nonhypnotic Suggestibility Research Articles

Direct Verbal Suggestibility as a Predictor of Placebo Hypoalgesia Responsiveness.

Reliably identifying good placebo responders has pronounced implications for basic research on, and clinical applications of, the placebo response. Multiple studies point to direct verbal suggestibility as a potentially valuable predictor of individual differences in placebo responsiveness, but previous research has produced conflicting results on this association. In two double-blind studies, we examined whether behavioral direct verbal suggestibility measures involving a correction for compliance would be associated with individual differences in responsiveness to conditioned and unconditioned placebo hypoalgesia using an established placebo analgesia paradigm. In study 1 (n = 57; mean [standard deviation] age = 23.7 [8.1] years; 77% women), we used behavioral hypnotic suggestibility as a predictor of placebo hypoalgesia induced through conditioning and verbal suggestion, whereas in study 2 (n = 78; mean [standard deviation] = 26.1 [7.4] years; 65% women), we measured nonhypnotic suggestibility and placebo hypoalgesia induced through verbal suggestion without conditioning. In study 1, the placebo hypoalgesia procedure yielded a moderate placebo response (g = 0.63 [95% confidence interval = 0.32 to 0.97]), but the response magnitude did not significantly correlate with hypnotic suggestibility (rs = 0.11 [-0.17 to 0.37]). In study 2, the placebo procedure did not yield a significant placebo response across the full sample (g = 0.11 [-0.11 to 0.33]), but the magnitude of individual placebo responsiveness significantly correlated with nonhypnotic suggestibility (rs = 0.27 [0.03 to 0.48]). These results suggest that the extent to which direct verbal suggestibility captures variability in placebo responsiveness depends on the use of conditioning and highlights the utility of suggestibility as a potential contributing factor to placebo responding when placebo hypoalgesia is induced through verbal suggestions.

Measuring Hypnotizability: The Case for Self-Report Depth Scales and Normative Data for the Long Stanford Scale

Conventional suggestion-based tests of hypnotizability have been criticized because they confound hypnotic and nonhypnotic suggestibility. One way around this might be to measure hypnotizability in terms of differences in suggestibility before and after hypnotic induction. However, analysis of data from a 1966 classic study by Hilgard and Tart confirms that difference scores are subject to statistical and methodological problems. Simple verbal hypnotic depth scales are presented as a useful alternative. They correlate well with conventional suggestion-based measures and enable the presence of hypnosis to be indexed independently of formal hypnotic induction procedures. Criticisms of depth scales are addressed, and normative data for the Long Stanford Scale of hypnotic depth are presented, along with data lending empirical support for the construct validity of depth reports.

Are patients with somatization disorder highly suggestible?

High suggestibility is widely regarded as an important feature of patients with medically unexplained symptoms (MUS), particularly those with multiple MUS [i.e. somatization disorder (SD)], although there are few empirical data attesting to this assumption. A study was therefore conducted to compare levels of non-hypnotic suggestibility in patients with SD and medical controls. A modified version of the Barber Suggestibility Scale was administered to 19 patients with SD and 17 controls with an established organic dystonia. Patients with SD were no more suggestible than control patients. Dystonia controls were more likely to deliberately comply with suggestions than the SD patients. Contrary to popular belief, high suggestibility is not necessarily a feature of SD.

Correlates of imaginative and hypnotic suggestibility in children

AbstractAs an extension of previous research by Braffman and Kirsch (1999) with adults, this study investigated the relationship between suggestibility and hypnotizability in a sample of 44 child psychiatric patients. Participants were assessed for various correlates of imaginative suggestibility while controlling for nonhypnotic suggestibility. Overall, nonhypnotic suggestibility accounted for most of the variance in hypnotizability (r = 0.73; p < 0.001), and vividness and absorption were found to predict unique variance in hypnotizability (r = 0.28; p < 0.001) when nonhypnotic suggestibility was controlled. These results support the view of hypnotic responsiveness as reflecting a continuum of suggestibility and serve to further weaken the contention that hypnosis produces an altered state of consciousness. Copyright © 2003 British Society of Experimental and Clinical Hypnosis

Mediation and moderation of hypnotic and cognitive‐behavioural pain reduction

AbstractThe mediator function of response expectancies and the moderator function of hypnotic and non‐hypnotic imaginative suggestibility were evaluated in the analogue treatment of pain. One hundred and sixty‐seven participants previously assessed for hypnotic and imaginative suggestibility were randomly assigned to distraction, cognitive‐behavioural package (i.e., Stress Inoculation Training), hypnotic cognitive‐behavioural package, hypnotic analgesia suggestion, placebo control, or no‐treatment control conditions. The four ‘active’ treatments reduced pain more than the no‐treatment control condition. There was no statistical difference in effectiveness between these four treatments, but only the cognitive‐behavioural package reduced pain more than the placebo control condition. Response expectancies partially mediated the effects of treatment on pain. Imaginative suggestibility, defined as a generalized tendency to respond to imaginative suggestions delivered outside of hypnosis, moderated the effects of the cognitive‐behavioural package. Contrary to prediction, neither hypnotic suggestibility, nor hypnotizability (operationalized as hypnotic suggestibility with imaginative suggestibility statistically controlled) moderated the effects of the hypnotic treatments. Copyright © 2003 British Society of Experimental and Clinical Hypnosis

Imaginative Suggestibility and Hypnotizability

More than a half-century of research aimed at identifying the predictors of hypnotic responding has been described as investigations of “hypnotizability.” Most of that research, however, has disregarded the well-established findings that (a) people respond to suggestion without being hypnotized almost as much as they do following a hypnotic induction, and (b) nonhypnotic and hypnotic suggestibility are highly correlated. More recent studies have provided the first empirical data on predictors of individual differences in response to the induction of hypnosis. These studies indicate that individual differences in hypnotic suggestibility can be accounted for completely by nonhypnotic suggestibility, expectancy, motivation, and reaction time. Because the amount of variance accounted for is as great as the reliability of the hypnotic-suggestibility scale, and because nonhypnotic suggestibility has been controlled, no additional variables are necessary to account for hypnotic suggestibility.

Correlates of hypnotizability: the first empirical study

AbstractBecause all of the effects of suggestion can be obtained without inducing hypnosis, hypnotizability is not the same thing as suggestibility. Hypnotizability is the change in suggestibility produced by inducing hypnosis. However, almost all studies purporting to measure hypnotizability have neglected to control for nonhypnotic (that is, so‐called ‘waking’) suggestibility. Thus, they have assessed the relation of suggestibility to various variables, but not the relation of hypnotizability to those variables. The one published study of the correlates of hypnotizability shows that it is predicted by expectancy and motivation, but not by absorption or fantasy proneness. Copyright © 1999 British Society of Experimental and Clinical Hypnosis

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.

Suggestibility or Hypnosis: What do our Scales Really Measure?

Conceptually, hypnotizability has always been defined as the increase in suggestibility produced by hypnosis. In practice, hypnotizability is measured as suggestibility following a hypnotic induction. The data indicate that these are different constructs. Although the induction of hypnosis inmases suggestibility to a substantial degree, the correlation between hypnotic and nonhypnotic suggestibility approximates the reliability coefficients of so-called hypnotizability scales. This indicates that hypnotic susceptibility scales are better measures of waking suggestibility than they are of hypnotizability The discordance between conceptual and operational definitions of hypnotizability can be resolved either by changing the conceptual definitions of hypnosis and hypnotizability or by reinterpreting hypnotizability scores as indexes of nonhypnotic, imaginative suggestibility.

A reexamination of the role of nonhypnotic suggestibility in hypnotic responding.

An alcohol-placebo paradigm was used to measure individual differences in the tendency to have directly suggested, as well as unsuggested, alterations in experience. Using the spectral analytic technique of C. G. Balthazard and E. Z. Woody (1992), such alterations in experience were found to be differentially correlated with the easiest items of the Harvard Group Scale of Hypnotic Susceptibility, Form A. The results indicated that easy hypnotic performances depend on some kind of social suggestibility not unique to hypnosis, and this factor becomes less important as the difficulty of the hypnotic performances increases. The results may also shed light on hypnotic sequelae, context effects, and two-component models of hypnotic performance.

A reexamination of the role of nonhypnotic suggestibility in hypnotic responding.

A reexamination of the role of nonhypnotic suggestibility in hypnotic responding.

The Harvard group scale of hypnotic susceptibility as a predictor of nonhypnotic suggestibility.

Abstract A behavioral measure of nonhypnotic suggestibility (the Suggested Syllables Test) was developed. The measure required that Ss determine the identity of tachistoscopically presented nonsense syllables when, unknown to Ss, no syllables were present. Responses to the Suggested Syllables Test were determined for 111 Ss (56 males and 55 females) who had been previously screened using the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) of Shor and E. Orne (1962). It was found that Ss who had scored low on HGSHS:A reported perceiving the suggested syllables significantly (p<.001) less frequently than did Ss with either medium or high HGSHS:A scores.