Neutral Hypnosis Research Articles

Is Hypnotic Induction Necessary to Experience Hypnosis and Responsible for Changes in Brain Activity?

The relevance of formal hypnotic induction to the experience of trance and its neural correlates is not clear, in that hypnotizability, beliefs and expectation of hypnosis may play a major role. The aim of the study was assessing the EEG brain activity of participants with high (highs) or low hypnotizability scores (lows), aware of their hypnotizability level and informed that the session will include simple relaxation, formal hypnotic induction and neutral hypnosis. A total of 16 highs and 15 lows (according to the Stanford Hypnotic Susceptibility Scale, form A) were enrolled. Their EEGs were recorded during consecutive conditions of open/closed-eyes relaxation, hypnotic induction, neutral hypnosis and post hypnosis not interrupted by interviews. The studied variables were theta, alpha and gamma power spectral density (PSD), and the Determinism (DET) and Entropy (ENT) of the EEG signal Multidimensional Recurrence Plot (mRP). Highs reported significantly greater changes in their state of consciousness than lows across the session. The theta, alpha and gamma PSD did not exhibit condition-related changes in both groups. The Alpha PSD was larger in highs than in lows on midline sites, and the different sides/regions' theta and gamma PSD were observed in the two groups independently from conditions. ENT showed no correlation with hypnotizability, while DET positively correlated with hypnotizability during hypnosis. In conclusion, the relevance of formal hypnotic induction to the experience of trance may be scarce in highs, as they are aware of their hypnotizability scores and expecting hypnosis. Cognitive processing varies throughout the session depending on the hypnotizability level.

Modulation of the heartbeat evoked cortical potential by hypnotizability and hypnosis.

Hypnotizability is a psychophysiological trait measured by scales and associated with several differences, including interoceptive accuracy and the morpho-functional characteristics of interoception-related brain regions. The aim of the study was to assess whether the amplitude of the heartbeat evoked cortical potential (HEP), a correlate of interoceptive accuracy, differs in participants with low (lows) and high (highs) hypnotizability scores (assessed by the Stanford Hypnotic Susceptibility Scale, Form A) before and after the induction of hypnosis. ECG and EEG were monitored in 16 highs and 15 lows during an experimental session, including open eyes baseline (B), closed eyes relaxation (R), hypnotic induction (IND), neutral hypnosis (NH), and post session baseline (Post). No significant difference was observed between groups and conditions in autonomic variables. The HEP amplitude was lower in highs than in lows at the right parietal site, likely due to hypnotizability related differences in the functional connection between the right insula and parietal cortex. It increased in highs and decreased in lows across the session, possibly due to the highs' preeminently internally directed attention and to the lows' possible disengagement from the task. Since interoception is involved in several cognitive-emotional functions, its hypnotizability related differences may contribute to the variability of experience and behavior in daily life.

Linear and Nonlinear Quantitative EEG Analysis during Neutral Hypnosis following an Opened/Closed Eye Paradigm

Hypnotic susceptibility is a major factor influencing the study of the neural correlates of hypnosis using EEG. In this context, while its effects on the response to hypnotic suggestions are undisputed, less attention has been paid to “neutral hypnosis” (i.e., the hypnotic condition in absence of suggestions). Furthermore, although an influence of opened and closed eye condition onto hypnotizability has been reported, a systematic investigation is still missing. Here, we analyzed EEG signals from 34 healthy subjects with low (LS), medium (MS), and (HS) hypnotic susceptibility using power spectral measures (i.e., TPSD, PSD) and Lempel-Ziv-Complexity (i.e., LZC, fLZC). Indeed, LZC was found to be more suitable than other complexity measures for EEG analysis, while it has been never used in the study of hypnosis. Accordingly, for each measure, we investigated within-group differences between rest and neutral hypnosis, and between opened-eye/closed-eye conditions under both rest and neutral hypnosis. Then, we evaluated between-group differences for each experimental condition. We observed that, while power estimates did not reveal notable differences between groups, LZC and fLZC were able to distinguish between HS, MS, and LS. In particular, we found a left frontal difference between HS and LS during closed-eye rest. Moreover, we observed a symmetric pattern distinguishing HS and LS during closed-eye hypnosis. Our results suggest that LZC is better capable of discriminating subjects with different hypnotic susceptibility, as compared to standard power analysis.

No evidence for theta power as a marker of hypnotic state in highly hypnotizable subjects

EEG spectral-power density was analyzed in a group of nine highly hypnotizable subjects via ten frontal, central, parietal, and occipital electrodes under four conditions: 1) wake state, 2) neutral hypnosis, 3) hypnotic suggestion for altering perception of tones, and 4) post-hypnosis. Results indicate no theta-power changes between conditions, challenging previous findings that increased theta power is a marker of hypnosis. A decrease in gamma power under hypnotic suggestion and an almost significant decrease under neutral hypnosis were observed, compared to post-hypnosis. Anteroposterior power distribution remained stable over all conditions. The results are discussed and compared to earlier studies, which report heterogenous findings.

Vittorio Benussi’s “Emotional Functional Autonomy”: Resumption and Re-Evaluation

ABSTRACT This study resumes and reevaluates the research on emotional functional autonomy developed by Vittorio Benussi in the 1920s, using hypnosuggestive methods. Four fundamental human emotions were studied in hypnosis: hope, happiness, despair, and unhappiness. Participants received training aimed at experiencing neutral hypnosis, characterized by the absence of any suggested images or suggested cognition. During the neutral hypnosis, the participants were asked to experience emotions isolated from all cognitive and imaginative experience so as to produce what can be assumed to be physiological responses driven by emotion only. The measured physiological variables were breathing and skin conductance. The study found evidence for a specific respiratory profile for each of the emotions examined.

Higher hypnotic suggestibility is associated with the lower EEG signal variability in theta, alpha, and beta frequency bands.

Variation of information in the firing rate of neural population, as reflected in different frequency bands of electroencephalographic (EEG) time series, provides direct evidence for change in neural responses of the brain to hypnotic suggestibility. However, realization of an effective biomarker for spiking behaviour of neural population proves to be an elusive subject matter with its impact evident in highly contrasting results in the literature. In this article, we took an information-theoretic stance on analysis of the EEG time series of the brain activity during hypnotic suggestions, thereby capturing the variability in pattern of brain neural activity in terms of its information content. For this purpose, we utilized differential entropy (DE, i.e., the average information content in a continuous time series) of theta, alpha, and beta frequency bands of fourteen-channel EEG time series recordings that pertain to the brain neural responses of twelve carefully selected high and low hypnotically suggestible individuals. Our results show that the higher hypnotic suggestibility is associated with a significantly lower variability in information content of theta, alpha, and beta frequencies. Moreover, they indicate that such a lower variability is accompanied by a significantly higher functional connectivity (FC, a measure of spatiotemporal synchronization) in the parietal and the parieto-occipital regions in the case of theta and alpha frequency bands and a non-significantly lower FC in the central region's beta frequency band. Our results contribute to the field in two ways. First, they identify the applicability of DE as a unifying measure to reproduce the similar observations that are separately reported through adaptation of different hypnotic biomarkers in the literature. Second, they extend these previous findings that were based on neutral hypnosis (i.e., a hypnotic procedure that involves no specific suggestions other than those for becoming hypnotized) to the case of hypnotic suggestions, thereby identifying their presence as a potential signature of hypnotic experience.

Hypnotic Automaticity in the Brain at Rest: An Arterial Spin Labelling Study

The feeling of automaticity reported by individuals undergoing a hypnotic procedure is an essential dimension of hypnosis phenomenology. In the present study, healthy participants rated their subjective experience of automaticity and resting-state arterial spin labelling (ASL) scans were acquired before and after a standard hypnotic induction (i.e., “neutral hypnosis”). The increase in perceived automaticity was positively associated with activity in the parietal operculum (PO) and seed-based coactivation analysis revealed additional associations in the anterior part of the supracallosal cingulate cortex (aMCC). This is consistent with the role of these regions in perceived self-agency and volition and demonstrates that these effects can be evidenced at rest, in the absence of overt motor challenges. Future studies should further examine if/how these changes in brain activity associated with automaticity might facilitate the responses to suggestions and contribute to clinical benefits of hypnosis.

Quantitative Sensory Testing (QST) Estimation of Regional Cutaneous Thermal Sensitivity During Waking State, Neutral Hypnosis, and Temperature Specific Suggestions

This study aimed to determine the effects of neutral hypnosis and hypnotic temperature suggestions in thermal and pain thresholds compared to resting state. Sixteen healthy medium or high hypnotizable volunteers were enrolled. Hypnotizability was assessed with the Hypnotic Induction Profile (HIP); QST was checked in resting state, in neutral hypnosis, after suggestions of heat and cold, and after deinduction. A significant increase in heat threshold was recorded during hypnosis with both cold and heat suggestions compared to neutral hypnosis. HIP induction score showed a linear correlation with changes of temperature thresholds after heat and cold suggestions. Thermal suggestions may result in a significant increase of heat perception thresholds with respect to neutral hypnosis. HIP score is related to thermal threshold changes. QST is a valuable and manageable tool to measure temperature threshold change during hypnosis.

THE EFFECTS OF HYPNOSIS AND HYPNOTIC SUGGESTIONS ON THE MISMATCH NEGATIVITY IN HIGHLY HYPNOTIZABLE SUBJECTS

The neural mechanisms associated with hypnosis were investigated in a group of 9 high hypnotizable subjects by measuring the mismatch negativity (MMN) component of the auditory event-related potential (ERP). ERPs were recorded using a passive oddball paradigm to sinusoidal standard and deviant tone stimuli of 500 and 520 Hz, respectively, in four conditions: prehypnosis, neutral hypnosis, hypnotic suggestion for altering the tone perception, and posthypnotic conditions. Earlier studies have indicated that hypnosis and hypnotic suggestions might have an effect on MMN, but the results of our study contradict these results: No statistically significant differences were found between the conditions in the MMN amplitudes.

THE ROLES OF RESPONSE EXPECTANCIES, BASELINE EXPERIENCES, AND HYPNOTIZABILITY IN SPONTANEOUS HYPNOTIC EXPERIENCES

This study evaluated factors underlying individual differences in spontaneous (unsuggested) experiences during hypnosis. Participants varying in hypnotizability (low, medium, and high) completed a questionnaire about various dimensions of consciousness they would expect to experience at the “deepest level of hypnosis” (expectancy), an eyes-closed resting condition (baseline), and their actual experiences during “neutral hypnosis” (hypnosis). Responses during hypnosis were characterized by higher scores in dimensions related to alterations in conscious experience, affect, and imagery, and lower scores in rationality and agency. Only highs and mediums evinced increases in altered experience and body image. Across conditions, highs reported greater alterations in time experience and lower self-awareness than other groups. Participants overall tended to overestimate the changes they would experience in hypnosis. Baseline and hypnosis correlated in various dimensions, including affect, arousal, and internal dialogue. After controlling for baseline scores and hypnotizability, expectancies correlated with some dimensions having to do with alterations in consciousness. In sum, spontaneous experiences during hypnosis are driven by response expectancies, hypnotizability, and baseline experiences, which show differential effects.

CAN SUBJECTIVE RATINGS OF ABSORPTION, DISSOCIATION, AND TIME PERCEPTION DURING “NEUTRAL HYPNOSIS” PREDICT HYPNOTIZABILITY?: An exploratory study

This study explored absorption, dissociation, and time perception on visual analogue scales (VAS) after a neutral hypnosis session to predict hypnotizability. Sixty-two subjects completed the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) and, during a neutral hypnosis session, VAS ratings of absorption, dissociation, and time perception. The findings indicated that 44% of subjects scored high, 35% medium, and 21% low on hypnotizability, as determined by scores on the SHSS:C. Dissociation VAS ratings significantly differed when comparing low to high and medium to high hypnotizable subjects. However, ratings were not significantly different between medium and low subjects. Significant positive correlation was found between dissociation VAS ratings and SHSS:C total scores. Future research is needed to validate this proof-of-concept study.

Functional Magnetic Resonance Imaging Demonstrates That Hypnosis Is Conscious and Voluntary

Hypnosis is a condition of modified consciousness (monoideism) resulting from a mental representation able to produce psychological and physical effects. The general belief is that hypnosis is conscious and voluntary, but the practical demonstration of this hypothesis is far to be demonstrated. Twenty healthy highly hypnotizable volunteers were studied during through functional magnetic resonance imaging during a task. The task was necessary because functional magnetic resonance imaging gives no interesting results in neutral hypnosis. During the hypnotic task, the prefrontal dorso-lateral cortex, genual cortex, dorsal anterior cingulate cortex, and orbital portion of the inferior frontal convolution (i.e. the Broadmann areas 9, 25, 32 and 47) were activated. Such areas are associated to egoic consciousness and voluntary processes. The results show that the hypothesis that hypnosis is conscious and voluntary is correct.

Hypnosis for reduction of background pain and pain anxiety in men with burns: A blinded, randomised, placebo-controlled study

Introduction‘Background pain’ and ‘pain anxiety’ are among the numerous problems of patients with burns. Non-pharmacological and pharmacological interventions have been used to reduce background pain and pain anxiety. This study compared the effectiveness of hypnosis and ‘neutral hypnosis’ (as a placebo in the control group) in decreasing the background burn pain and pain anxiety of adult male survivors with burns. DesignThis is a blinded, randomised, placebo-controlled study. MethodsSixty men with burns were included in the minimisation method (30 individuals in the intervention group and 30 individuals in the control group). Four hypnotherapy sessions were performed every other day for each participant in the intervention group. Four neutral hypnosis sessions were performed every other day in the control group. Burn pain and pain anxiety of the patients in both groups were measured at the end of the second and fourth sessions. Repeated measures ANOVA was used for data analysis. ResultsThere was no significant difference between the groups in the reduction in background pain intensity. There was a significant reduction in background pain quality and pain anxiety in the intervention group during the four hypnosis sessions. After two hypnotherapy sessions, a significant reduction was observed in the level of background pain quality and pain anxiety of participants. ConclusionHypnosis is effective in reducing background pain quality and pain anxiety of men with burns.

Varieties of attention in hypnosis and meditation

In their commentary, Oakley and Halligan (2011) echo their recent thoughts regarding the cognitive neuroscience of hypnosis and suggestion (Oakley & Halligan, 2009, 2010). Here we address some of the issues they raise concerning the quest for neuropsychological markers of hypnotic states, the use of hypnotic vs. posthypnotic suggestions, and the potential for other forms of atypical attention such as meditative practices to elucidate hypnosis and de-automatization. Oakley and Halligan twice allude to the paucity of data indicating a special neuropsychological ‘‘state’’ of hypnosis sometimes known as ‘‘trance’’ (2011). The authors note, however, that recent investigations show some promise of identifying a neural marker of hypnosis. Whereas some evidence, including our own research, supports the idea that hypnotic phenomena typically follow suggestions even in the absence of a formal induction procedure (Mazzoni et al., 2009; McGeown et al., 2012; Raz, Kirsch, Pollard, & Nitkin-Kaner, 2006), other research findings may serve to support a distinctive physiological marker unique to hypnosis or to hypnotic suggestions (e.g., Cojan et al., 2009; Demertzi et al., 2011; Pyka et al., 2011; Raz, Fan, & Posner, 2005; Terhune, Cardena, & Lindgren, 2010; Vanhaudenhuyse et al., 2009). Scholars, however, hardly agree even about the behavioral and phenomenological characteristics that typify ostensible hypnotic planes. For example, distinct sub-types of highly hypnotically suggestible individuals seem to diverge in their experience and behavior throughout hypnosis, challenging the view of hypnosis as a unitary concept (Terhune, Cardena, & Lindgren, 2011). In addition, the literature provides mixed accounts of how psychological factors such as context, sense of control, relaxation, and expectation relate to hypnosis (Kihlstrom, 2008). An adequate psychological model, therefore, would be instrumental to understanding hypnosis from a physiological perspective. In research settings, as in clinical practice, specific suggestions often accompany hypnosis. Few reports, however, have investigated brain and behavioral correlates of ‘‘neutral’’ hypnosis sans post-induction suggestions (Cardena, 2005; Cardena, Jonsson, Terhune, & Marcusson-Clavertz, 2012; Kihlstrom & Edmonston, 1971; McGeown, Mazzoni, Venneri, & Kirsch, 2009). These few published accounts, moreover, rarely control for the effects of implicit suggestions—for relaxation, drowsiness, and focused attention—that are ubiquitous in classic hypnotic inductions. In addition, it appears that the influence of neutral hypnosis is different from that of hypnosis with explicit suggestions. For example, in response to incongruent Stroop stimuli, highly hypnotically suggestible individuals demonstrated increased conflict-related brain activity in the anterior cingulate cortex (ACC) following neutral induction (Egner, Jamieson, & Gruzelier, 2005); conversely, when offered an explicit suggestion to perceive the stimuli as meaningless symbols, participants showed decreased fMRI signal in the ACC (Raz et al., 2005). Further research, therefore, would need to carefully tease apart such hypnotic variations. Whether or not hypnosis involves distinct neurocognitive indices, posthypnotic suggestion (PHS) provides a useful experimental alternative to hypnotic suggestion. PHS refers to a condition during common wakefulness following termination of the hypnotic experience, wherein a subject is compliant with a suggestion made during the hypnotic episode. Thus, PHS keeps cognitive performance untarnished by potential confounding factors associated with the ritual of hypnosis. Oakley

The neurophenomenology of neutral hypnosis

IntroductionAfter a hypnotic induction, medium and highly hypnotizable individuals often report spontaneous alterations in various dimensions of consciousness. Few studies investigating these experiences have controlled for the inherent demands of specific hypnotic suggestions and fewer still have considered their dynamic properties and neural correlates. MethodsWe adopted a neurophenomenological approach to investigate neutral hypnosis, which involves no specific suggestion other than to go into hypnosis, with 37 individuals of high, medium, and low hypnotizability (Highs, Mediums, and Lows). Their reports of depth and spontaneous experience at baseline, following a hypnotic induction, and then after multiple rest periods were analyzed and related to EEG frequency band power and global functional connectivity. ResultsHypnotizability was marginally associated with lower global functional connectivity during hypnosis. Perceived hypnotic depth increased substantially after the induction especially among Highs and then Mediums, but remained almost unchanged among Lows. In the sample as a whole, depth correlated moderately to strongly with power and/or power heterogeneity for the fast EEG frequencies of beta2, beta3, and gamma, but independently only among Highs. The spontaneous phenomenology of Lows referred primarily to the ongoing experiment and everyday concerns, those of Mediums to vestibular and other bodily experiences, and those of Highs to imagery and positive affect/exceptional experiences. The latter two phenomena were associated with lower global functional connectivity during hypnosis. Imagery correlated positively with gamma power heterogeneity and negatively with alpha1 power heterogeneity. Generally, the pattern of correlations for the Highs was the opposite of that for the Lows. ConclusionsExperienced hypnotic depth and spontaneous phenomena following a neutral hypnotic induction vary as a function of hypnotizability and are related to global functional connectivity and EEG band wave activity.

William E. Edmonston, Jr.: Editor, 1968–1976

This article is part of an occasional series profiling editors of the American Journal of Clinical Hypnosis (AJCH). William E. Edmonston was the second editor, succeeding Milton H. Erickson. His research focused on the use of conditioning paradigms and psychophysiological measures to explore a wide variety of hypnotic phenomena, leading to a “neo-Pavlovian” theory of neutral hypnosis as physiological relaxation (anesis). A longtime professor of psychology at Colgate University, he created an interdisciplinary undergraduate major in neuroscience, and was named New York State College Professor of the Year in 1988. He gave the Journal a new look, and a greater balance of clinical and experimental papers. The article also provides background on George Barton Cutten, George H. Estabrooks, and Frank A. Pattie, pioneers of hypnosis who were linked to Edmonston.

How to put hypnosis into a placebo pill?

Many case studies and several controlled clinical trials have indicated the effectiveness of hypnotherapy for some medical conditions. However, because of methodological inadequacies hypnotherapy is still criticized for not having strong scientific evidence to support its claims. While randomized placebo-controlled clinical trial is generally accepted as the gold standard study design, creating a credible placebo control for hypnotherapy is a major challenge. This paper recommends "neutral hypnosis" as a credible placebo control for hypnotherapy trials.

Cortex functional connectivity as a neurophysiological correlate of hypnosis: An EEG case study

Cortex functional connectivity associated with hypnosis was investigated in a single highly hypnotizable subject in a normal baseline condition and under neutral hypnosis during two sessions separated by a year. After the hypnotic induction, but without further suggestions as compared to the baseline condition, all studied parameters of local and remote functional connectivity were significantly changed. The significant differences between hypnosis and the baseline condition were observable (to different extent) in five studied independent frequency bands (delta, theta, alpha, beta, and gamma). The results were consistent and stable after 1 year. Based on these findings we conclude that alteration in functional connectivity of the brain may be regarded as a neuronal correlate of hypnosis (at least in very highly hypnotizable subjects) in which separate cognitive modules and subsystems may be temporarily incapable of communicating with each other normally.

THE PHENOMENOLOGY OF DEEP HYPNOSIS: QUiescent and Physically Active

To study the phenomenology of hypnotic virtuosos, the author employed a 2 (hypnosis vs. control) × 3 (quiescent, pedaling a stationary bike, having a motor pedal the bike) within-subjects design with quantitative and qualitative measures. In a “neutral hypnosis” context with the only suggestion being to go as deeply into hypnosis as possible, participants reported alterations in body image, time sense, perception and meaning, sense of being in an altered state of awareness, affect, attention, and imagery. They also mentioned less self-awareness, rationality, voluntary control, and memory. Analyses of the 3 physical conditions showed that hypnotic experiences were overall similar, although quiescence was more conducive to alterations of body image and reports of depth. These results suggest that hypnotic virtuosos have alterations of consciousness that can be better conceptualized as distinct states rather than being on a continuum. This study was supported in part by the American Psychological Association’s MFP and Doctoral Dissertation fellowships. An earlier version of this paper received the Crasilneck award from SCEH after being presented at the 39th Annual Meeting of the Society for Clinical and Experimental Hypnosis, Asheville, North Carolina. Thanks to Charles Tart, Ph.D., for his supervision; to Jaime Curts, Ph.D., for statistical consultation; and to Grant Benham, Ph.D., Dana Barth, and Lupita Weiner for editorial assistance.

Hypnotic Susceptibility and Hypnosis Modulate the Endothelial Response to Acute Stress

Neutral hypnosis is commonly used as a relaxation technique. Even if many of its physiological correlates as well as the main neuropsychological characteristics of hypnotizable individuals have been described, it is still unclear whether the hypnotic state (state theory) or the cognitive capabilities of awake hypnotizable individuals per se (trait theory) are responsible of the relaxation effects induced by hypnosis [1]. Indeed, specific suggestions have been proven to induce cognitive emotional experiences, associated to specific physiological patterns,which can be different in relation to hypnotizability and/or hypnosis. In recent studies [2] it has been demonstrated that awake hypnotizable subjects, at difference with non hypnotizable ones,were able to buffer the autonomic effects of a moderately unpleasant cognitive stimulation. [...]