Types of suggestibility: Relationships among compliance, indirect, and direct suggestibility

A double-blind randomized clinical trial on the suggestive effect of anxiety management questionnaires in dental emergencies

Objective

Dental anxiety is widespread among both children and adults. To diagnose dental anxiety, standardized anxiety questionnaires are recommended. Based on the suggestive nature of the questionnaires, the study aimed to find out whether asking respondents about personal coping strategies before dental treatment influences their anxiety.

Methods

This prospective, double-blind, randomized controlled clinical trial included a total of 158 patients of a university dental clinic on emergency service. The intervention group (n = 82) received the Coping with Anxiety Questionnaire (CAQ) and the control group (n = 76) the Hierarchical Anxiety Questionnaire (HAF). State anxiety scores were assessed by using the State-Trait Anxiety Inventory (STAI) before and after the completion of each questionnaire.

Results

Anxiety decreased in the intervention group (CAQ) (p < 0.001) and increased in the control group (HAF) (p < 0.001).

Conclusion

Within the limitations of the current study, a diagnostic tool of a standardized questionnaire for the assessment to assess personal coping strategies decreased state anxiety in comparison to a questionnaire assessing anxiety.

Clinical trial registration

https://www.drks.de, German Trials Register (DRKS00032450).

Absorption and dissociation mediate the relationship between direct verbal suggestibility and impulsivity/compulsivity

Direct verbal suggestibility refers to the capacity for an individual to experience perceptual, motor, affective and cognitive changes in response to verbal suggestions. Suggestibility is characterized by pronounced, yet reliable, inter-individual differences. Previous research and theoretical considerations suggest that greater impulsivity and compulsivity is associated to higher suggestibility, but the characteristics and mediating factors of this association are poorly understood. Using established psychometric measures in an online sample, we found positive correlations between the domain comprising impulsivity, compulsivity and behavioural activation, and the domain of suggestibility, dissociation and absorption. We also observed that dissociation and absorption mediated the link between suggestibility and impulsivity, and between suggestibility and behavioural activation, respectively. These results confirm the positive link between suggestibility and the impulsivity/compulsivity domain and shed new light on the characterisation of traits associated with suggestibility.

Hypnotic suggestibility in dissociative and related disorders: A meta-analysis

Elevated responsiveness to verbal suggestions is hypothesized to represent a predisposing factor for dissociative disorders (DDs) and related conditions. However, the magnitude of this effect has not been estimated in these populations nor has the potential moderating influence of methodological limitations on effect size variability across studies. This study assessed whether patients with DDs, trauma- and stressor-related disorders (TSDs), and functional neurological disorder (FND) display elevated hypnotic suggestibility. A systematic literature search identified 20 datasets. A random-effects meta-analysis revealed that patients displayed greater hypnotic suggestibility than controls, Hedges's g=0.92 [0.66, 1.18]. This effect was observed in all subgroups but was most pronounced in the DDs. Although there was some evidence for publication bias, a bias-corrected estimate of the group effect remained significant, g=0.57 [0.30, 0.85]. Moderation analyses did not yield evidence for a link between effect sizes and methodological limitations. These results demonstrate that DDs and related conditions are characterized by elevated hypnotic suggestibility and have implications for the mechanisms, risk factors, and treatment of dissociative psychopathology.

Availability of synchronous information in an additional sensory modality does not enhance the full body illusion

The Full body illusion (FBI) is an illusion in which participants experience a change in self-location to a body that is perceived from a third-person perspective. The FBI is usually induced through experimenter generated stroking but can also be induced through self-generated stroking. In four experiments (three preregistered) we compared a self-generated stroking induction condition to a self-generated movement condition, where the only difference between conditions was the presence or absence of touch. We investigated whether the illusion reflects an all-or-nothing phenomenon or whether the illusion is influenced by the availability of synchronous information in an additional sensory modality. As a prerequisite, we investigated whether the FBI can also be induced using just self-generated movement in the absence of synchronous touch. Illusion strength was measured through illusion statements. Participants reported an equally strong illusion for both induction methods in Experiments 1, 2 and 3. In the third experiment, we additionally measured the time of illusion onset. Like the illusion strength measures, the illusion onset times did not differ between the two induction methods. In the fourth experiment participants only completed the self-generated movement condition. Again, they reported the FBI, demonstrating that the findings of Experiments 1, 2 and 3 were not dependent on the presence of a condition that used synchronous touch. Together, these findings confirm the hypothesis that the FBI is an all-or-nothing phenomenon and that adding additional multisensory synchronicity does not help to enhance the strength, onset time or onset probability of the illusion.

A Critical Review of Standardized Measures of Hypnotic Suggestibility

The most well-established finding gleaned from decades of experimental hypnosis research is that individuals display marked variability in responsiveness to hypnotic suggestions. Insofar as this variability impacts both treatment outcome in therapeutic applications of hypnosis as well as responsiveness to suggestions in experimental contexts, it is imperative that clinicians and researchers use robust measures of hypnotic suggestibility. The current paper critically evaluates contemporary measures of hypnotic suggestibility. After reviewing the most widely used measures, we identify multiple properties of these instruments that result in the loss of valuable information, including binary scoring and single-trial sampling, and hinder their utility, such as the inclusion of suboptimal suggestion content. The scales are not well-suited for contemporary research questions and have outlived their usefulness. We conclude by outlining ways in which the measurement of hypnotic suggestibility can be advanced.

Trait phenomenological control predicts experience of mirror synaesthesia and the rubber hand illusion

In hypnotic responding, expectancies arising from imaginative suggestion drive striking experiential changes (e.g., hallucinations) - which are experienced as involuntary - according to a normally distributed and stable trait ability (hypnotisability). Such experiences can be triggered by implicit suggestion and occur outside the hypnotic context. In large sample studies (of 156, 404 and 353 participants), we report substantial relationships between hypnotisability and experimental measures of experiential change in mirror-sensory synaesthesia and the rubber hand illusion comparable to relationships between hypnotisability and individual hypnosis scale items. The control of phenomenology to meet expectancies arising from perceived task requirements can account for experiential change in psychological experiments.

The rubber hand illusion in hypnosis provides new insights into the sense of body ownership

Body ownership can be experimentally investigated with the rubber hand illusion (RHI), in which watching a rubber hand stroked synchronously with one’s own hidden hand induces a feeling of ownership over the rubber hand. The aim of this study was to investigate response to the RHI in high (N = 21) and low (N = 19) hypnotizable individuals in normal waking state and in hypnosis. Response to the RHI was measured via a question on the illusory feeling of ownership and with proprioceptive drift. The Highs expressed an overall feeling of more ownership over the rubber hand in both the normal waking state and hypnosis, although both groups gave higher ownership scores after synchronous than after asynchronous stroking and the difference between conditions was similar across groups. Conversely, the proprioceptive drift appeared to be differentially modulated by hypnosis and hypnotic suggestibility: it was increased in the Highs and decreased in the Lows after hypnosis induction. These findings hint at an interplay between hypnotic suggestibility and hypnosis in modulating response to the RHI. The selective breakdown of proprioceptive drift among the Lows suggests resistance to recalibrate one’s own limb in hypnosis.

HYPNOTIC RESPONSIVENESS AND NONHYPNOTIC SUGGESTIBILITY: DISPARATE, SIMILAR, OR THE SAME?

This study examined if participants respond to different types of suggestions, including hypnosis, uniquely or similarly. This study used 9 suggestibility measures and hypothesized a 3-factor model. It was hypothesized that hypnosis, Chevreul's pendulum, and body-sway would load on the first factor; the odor test, progressive weights, and placebo on the second factor; and conformity, persuasibility, and interrogative suggestibility would load on the third factor. The study comprised 110 college students. Factor analyses failed to result in three factors. Additional attempts at two and three-factor models were also rejected. Hypnosis had no strong relationship with the various suggestibility measures. Thus, no clearly delineated factor structure of suggestibility emerged, indicating that the domain of suggestibility seems to be neither a single attribute, trait, or group of related abilities. Implications are discussed.

The future of professional hypnosis: comment on kirsch, mazzoni, and montgomery

I believe the paper by Kirsch, Mazzoni, and Montgomery (this issue) should surprise about 95% of ASCH members (maybe only 93% of SCEH members) because the three facts espoused in their paper speciously seem to be 100% true. To paraphrase from their abstract: 1) nothing that can be produced by hypnotic induction plus suggestion cannot also be produced by suggestion alone; 2) administration of a hypnotic induction does not produce a meaningful increase in response to suggestion relative to suggestion alone; and 3) responsivity to suggestions are highly correlated to responsivity on the same measure when preceded by a hypnotic induction ceremony. In order to persuade that these propositions are true, several objections to them must be addressed. However, just because one's facts are true does not mean that one's interpretation of the facts and their interrelationships are also true. The ramifications of the above facts and their interrelationships for the future of professional hypnosis (experimental, clinical and forensic) are identified and discussed.

Individual Differences in the Rubber Hand Illusion Are Related to Sensory Suggestibility

In the rubber hand illusion (RHI), watching a rubber hand being stroked in synchrony with one’s own hidden hand may induce a sense of ownership over the rubber hand. The illusion relies on bottom-up multisensory integration of visual, tactile, and proprioceptive information, and on top-down processes through which the rubber hand is incorporated into pre-existing representations of the body. Although the degree of illusory experience varies largely across individuals, the factors influencing individual differences are unknown. We investigated whether sensory suggestibility might modulate susceptibility to the RHI. Sensory suggestibility is a personality trait related to how individuals react to sensory information. Because of its sensory nature, this trait could be relevant for studies using the RHI paradigm. Seventy healthy volunteers were classified by Sensory Suggestibility Scale (SSS) scores as having high or low suggestibility and assigned to either a high- (High-SSS) or a low-suggestibility (Low-SSS) group. Two components of the RHI were evaluated in synchronous and asynchronous stroking conditions: subjective experience of sense of ownership over the rubber hand via a 9-statement questionnaire, and proprioceptive drift as measured with a ruler. The High-SSS group was generally more susceptible to the subjective component; in the synchronous condition, they rated the statement assessing the sense of ownership higher than the Low-SSS group. The scores for this statement significantly correlated with the total SSS score, indicating that the higher the sensory suggestibility, the stronger the sense of ownership. No effect of sensory suggestibility on proprioceptive drift was observed, suggesting that the effect is specific for the subjective feeling of ownership. This study demonstrates that sensory suggestibility may contribute to participants’ experience of the illusion and should be considered when using the RHI paradigm.

Neurophysiological attributes of the hypnotic state and the utility of hypnosis in pediatric medicine and burn care

Three articles of special interest to the hypnosis community recently appeared in the general scientific and medical literatures. The first paper is a thoughtful review of the clinical applications of hypnosis in pediatric settings. The second article reports the findings of a randomized, controlled trial of hypnosis for burn-wound care, carried out at the University of Washington Medical School. The third article describes an innovative EEG laboratory case study tracking the cortex functional connectivity of a highly hypnotizable subject across various baseline and experimental conditions. These three articles are sturdy examples of how hypnosis illuminates (and is illuminated by) medical and psychological science.

Salient findings: hypnotizability as core construct and the clinical utility of hypnosis

Six papers of special interest to the hypnosis community have recently appeared in the general scientific literatures. Three of these papers were published as part of the 2006 Cochrane Collaboration on the utility of medical interventions. These reviews analyze the research literature on the efficacy of hypnosis for treatment of needle-related pain in children, pain management during childbirth, and conversion disorder. Hypnosis is the most promising psychological intervention studied for needle-related procedural pain and distress in children and adolescents; it is effective as an adjunctive analgesic during childbirth; and it is of uncertain usefulness in treatment of conversion disorder. A second cluster of three studies unambiguously demonstrates the central role of hypnotizability as a predictor of responsiveness in laboratory, analogue treatment, and medical practice settings. One of these articles may well be the most important hypnosis paper in many years.

What is a suggestion? The neuroscience of implicit processing heuristics in therapeutic hypnosis and psychotherapy

Neuroscience and bioinformatics research on activity-dependent gene expression and brain plasticity in memory and learning are used to reconceptualize a fundamental question of therapeutic hypnosis, "What is a suggestion?" John Kihlstrom's cognitive-behavioral perspective of implicit (unconscious) and explicit (conscious) memory and Eric Kandel's Nobel Prize winning neurobiological research are integrated for a 30-year update of Milton H. Erickson's "neuro-psycho-physiology" of therapeutic hypnosis. Implicit processing heuristics are proposed as a more general framework for Erickson's concept of permissive indirect suggestions in therapeutic hypnosis and psychotherapy. These perspectives are illustrated by utilizing implicit processing heuristics to facilitate the four-stage creative process in converting implicit to explicit memory in a brain-damaged patient.

The future of professional hypnosis: comment on Kirsch, Mazzoni, and Montgomery

I believe the paper by Kirsch, Mazzoni and Montgomery (this issue) should surprise about 95% of ASCH members (maybe only 93% of SCEH members) because the three facts espoused in their paper speciously seem to be 100% true. To paraphrase from their abstract: 1) nothing that can be produced by hypnotic induction plus suggestion cannot also be produced by suggestion alone; 2) administration of a hypnotic induction does not produce a meaningful increase in response to suggestion relative to suggestion alone; and 3) responsivity to suggestions are highly correlated to responsivity on the same measure when preceded by a hypnotic induction ceremony. In order to persuade that these propositions are true, several objections to them must be addressed. However, just because one's facts are true does not mean that one's interpretation of the facts and their interrelationships are also true. The ramifications of the above facts and their interrelationships for the future of professional hypnosis (experimental, clinical and forensic) are identified and discussed.