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Hypnosis has puzzled scientists for centuries, and particularly the reason why some people are prone to engaging in suggested experiences discordant with external reality. Absorption in internal experience is one key component of the hypnotic response. The neuropeptide oxytocin has been posited to heighten sensitivity to external cues, and it is possible that individual differences in oxytocin-related capacity to engage in external or internal experiences influences hypnotic response. To test this proposal, 185 Caucasian individuals provided saliva samples for analysis of polymorphisms in the oxytocin receptor gene, COMT, and independently completed standardized measures of hypnotizability and absorption. Participants with the GG genotype at rs53576 were characterized by lower hypnotizability and absorption scores than those with the A allele; there was no association between hyponotizability and COMT. These findings provide initial evidence that the capacity to respond to suggestions for altered internal experience is influenced by the oxytocin receptor gene, and is consistent with evidence that oxytocin plays an important role in modulating the extent to which people engage with external versus internal experiences., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

It has long been argued that hypnosis cannot promote behaviors that people will not otherwise engage in. Oxytocin can enhance trust in others, and may promote the extent to which a hypnotized person complies with the suggestion of a hypnotist. This double-blind placebo study administered oxytocin or placebo to high hypnotizable participants (N = 28), who were then administered hypnotic suggestions for socially unorthodox behaviors, including swearing during the experiment, singing out loud, and dancing in response to a posthypnotic cue. Participants who received oxytocin were significantly more likely to swear and dance than those who received the placebo. This finding may be interpreted in terms of oxytocin increasing social compliance in response as a function of (a) increased trust in the hypnotist, (b) reduced social anxiety, or (c) enhanced sensitivity to cues to respond to experimental expectations. These results point to the potential role of oxytocin in social persuasion.

Since hypnosis was popularly recognized in the nineteenth century, the phenomenon of hypnotizability has remained poorly understood. The capacity to increase hypnotizability has important implications because it may increase the number of people who can benefit from hypnotic interventions for psychological and medical conditions. Current theories emphasize that rapport between hypnotist and subject is pivotal to motivate the respondent to engage in strategies that allows them to suspend reality and respond to suggestions. The neuropeptide oxytocin is implicated in social bonding, and enhances a range of social behaviors in animals and humans. This study tested the proposal that oxytocin administration, which enhances social bonding in humans, may enhance hypnotic responding by administering intranasal spray of oxytocin or placebo prior to hypnosis in 40 low hypnotizable male subjects. When low hypnotizable individuals were administered oxytocin via nasal spray, their level of hypnotic responding increased significantly compared to hypnotic responding levels prior to oxytocin administration. This is the first demonstration of a neurochemical basis for hypnotic responding, and points to a potential neural mechanism to explain hypnotizability., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This study tests the proposal that hypnotic responding is effortless. The authors compared the responses of high and low hypnotizable participants (N = 70) in and out of hypnosis on a dual-task paradigm in which they were required to maintain hypnotic blindness during presentation of visual stimuli of varying salience intensities while simultaneously completing a secondary task. Whereas high hypnotizable participants in both hypnosis and wake conditions reported comparable levels of conviction in the hallucination suggestion, hypnotized highs performed poorer on the secondary task when the stimulus was present. Performance on the secondary task deteriorated when the visual stimulus was intensified. These findings contradict the notion that hypnotic response is not demanding on cognitive resources and suggest that increased effort is required to resolve the extent of conflict between reality and suggestion.

Despite the importance of intrusive memories in clinical disorders, research has been limited by a dearth of paradigms that permit experimental study of intrusions. This study describes a hypnotic paradigm for eliciting intrusive memories. Forty-nine highly hypnotisable participants nominated a distressing memory prior to being hypnotised. During hypnosis, they received the suggestion that they would remember the memory in response to a designated cue after the hypnosis session. Half of the participants also received a posthypnotic amnesia suggestion for the source of the memory. Following hypnosis, all participants completed a cognitive task and during the task received the cue to recall the memory. Results demonstrated that memories experienced after posthypnotic amnesia were experienced as more involuntary and more distressing than those that were knowingly retrieved. Participants in the posthypnotic amnesia condition also demonstrated greater interference on the cognitive task after the retrieval cue was given than those who intentionally retrieved the memory. These findings suggest that posthypnotic suggestion provides a useful paradigm to elicit intrusive memories under experimental conditions., (2010 Elsevier Ltd. All rights reserved.)

This study hypothesized that hypnosis would enhance thought suppression by minimizing the effect of cognitive load. Twenty-eight high and 29 low hypnotizable hypnotized participants received the cognitive load of learning a 6-digit number. Participants then received either a suppression instruction or no instruction for a personal memory of a failure experience. Thought-suppression effectiveness was indexed by measures of self-report monitoring, competition of scrambled sentences, and facial electromyography. Low hypnotizable participants who received the suppression instruction displayed postsuppression rebound on the sentence-unscrambling task. In contrast, high hypnotizable participants did not display any rebound effects. These findings support the proposition that hypnosis facilitates thought suppression.

This study investigated the influence of hypnotic emotional inhibition on emotional response to and recall of emotional features of autobiographical memories. Twenty-nine high hypnotizable participants were administered a hypnotic induction and either emotional suppression or control instructions and then were asked to recall a personal distressing or neutral autobiographical memory. Dependent variables included self-reported emotion, EMG corrugator muscle activity, and use of affective descriptors in autobiographical memories. Participants in the suppression condition displayed less emotional responsivity on self-report and EMG corrugator muscle activity than other participants during recall of the distressing memory. In contrast, emotional suppression did not influence the use of affective descriptors in the content of personal memories. These findings point to the capacity for hypnotic emotional inhibition to differentially influence affective and semantic components of the emotional response.

Much research indicates that attempts to suppress thoughts lead to increased accessibility of those thoughts, especially when additional cognitive load is present. On the premise that hypnosis may permit more effective management of cognitive load, it was hypothesized that hypnosis may enhance more effective thought suppression. The present research examined whether the obstacle of cognitive load could be bypassed using hypnosis to facilitate successful thought suppression. Thirty-nine high and 40 low hypnotizable participants were hypnotized and received either a suppression instruction or no instruction for a memory of an embarrassing experience and subsequently completed a sentence-unscrambling task that indexed accessibility of embarrassing thoughts. Whereas lows instructed to suppress displayed a delayed increase in suppressed thoughts, highs did not. These findings support the proposition that hypnosis facilitates thought suppression.

The long-term benefits of cognitive behaviour therapy (CBT) for trauma survivors with acute stress disorder were investigated by assessing patients 3 years after treatment. Civilian trauma survivors (n=87) were randomly allocated to six sessions of CBT, CBT combined with hypnosis, or supportive counselling (SC), 69 completed treatment, and 53 were assessed 2 years post-treatment for post-traumatic stress disorder (PTSD) with the Clinician-Administered PTSD Scale. In terms of treatment completers, 2 CBT patients (10%), 4 CBT/hypnosis patients (22%), and 10 SC patients (63%) met PTSD criteria at 2-years follow-up. Intent-to-treat analyses indicated that 12 CBT patients (36%), 14 CBT/hypnosis patients (46%), and 16 SC patients (67%) met PTSD criteria at 2-year follow-up. Patients who received CBT and CBT/hypnosis reported less re-experiencing and less avoidance symptoms than patients who received SC. These findings point to the long-term benefits of early provision of CBT in the initial month after trauma.

Two studies investigated management of conflict in hypnosis by subtly increasing the brightness of a visual stimulus during a suggestion for hypnotic blindness to the stimulus. In Study 1, 23 high hypnotizable participants were administered a hypnotic suggestion for blindness to a projected light. For half the participants, the brightness of the light was intensified during the suggestion. Behavioral ratings and online analog-dial measurement indicated that participants reported decreased hypnotic blindness during the increased conflict condition. In Study 2, 20 participants were administered the nonexperimental procedure to investigate the impact of demand characteristics in this paradigm. Parallel findings in Studies 1 and 2 indicated that demand characteristics may explain the response to hypnotic conflict. Limitations in applying the nonexperimental procedure to this paradigm and the need for further investigation are discussed.

This study investigated the roles of hypnotizability and hypnosis in suggested emotional numbing. Thirty-two high hypnotizable and 32 low hypnotizable participants were administered either a hypnotic or wake induction and were then presented with emotionally distressing and neutral images during a suggestion for emotional numbing or a control condition. Emotional response was indexed through self-report and EMG corrugator-muscle activity. High hypnotizable participants, in both the hypnosis and wake conditions, reported more diminished emotional responses on self-report and EMG corrugator-muscle activity than low hypnotizable participants during the emotional-numbing suggestion. These findings suggest that elevated hypnotic susceptibility, rather than hypnosis, is an important mediator of emotional numbing. The importance of individual differences in emotional numbing is discussed.

This research represents the first controlled treatment study of hypnosis and cognitive- behavioral therapy (CBT) of acute stress disorder (ASD). Civilian trauma survivors (N=87) who met criteria for ASD were randomly allocated to 6 sessions of CBT, CBT combined with hypnosis (CBT-hypnosis), or supportive counseling (SC). CBT comprised exposure, cognitive restructuring, and anxiety management. CBT-hypnosis comprised the CBT components with each imaginal exposure preceded by a hypnotic induction and suggestions to engage fully in the exposure. In terms of treatment completers (n=69), fewer participants in the CBT and CBT-hypnosis groups met criteria for posttraumatic stress disorder at posttreatment and 6-month follow-up than those in the SC group. CBT-hypnosis resulted in greater reduction in reexperiencing symptoms at posttreatment than CBT. These findings suggest that hypnosis may have use in facilitating the treatment effects of CBT for posttraumatic stress., (Copyright (c) 2005 APA, all rights reserved)

The extent to which hypnotic suggestions are perceived as real is central to understanding hypnotic response. This study indexed the reality attributed to hypnotic suggestion through subtle projection of a visual image during simultaneous suggestion for a visual hallucination that resembled the projected image. Twenty real hypnotized and 20 simulating nonhypnotized participants were administered a hypnotic induction and given a suggestion to hallucinate a shape, and then the projected image was introduced. Following the hypnosis session, an Experiential Analysis Technique was employed to index experiential responses. Real, but not simulating, participants made comparable reality ratings when the projected image was absent and present. Reals, but not simulators, also reported more effort in maintaining belief in the suggestion when the projection was absent. These findings suggest that the reality attributed to a hypnotic suggestion cannot be attributed to demand characteristics.

Twenty high hypnotizable and 20 low hypnotizable participants were administered a hypnotic induction and then presented with emotionally distressing and neutral visual images. Half the participants were administered a suggestion for emotional numbing. Participants were then asked to rate the valence of neutral words that were preceded by subliminal presentations of the negative and neutral images. Whereas highs who received the emotional-numbing suggestion reported comparable ratings of the words following presentations of the negative and neutral images, highs in the control condition and lows in both conditions reported more positive ratings of words that were preceded by the negative stimuli. These findings suggest that the subliminally presented negative stimuli led participants to rate the subsequent neutral words more positively. In contrast, hypnotic emotional numbing diminished this pattern in highs. These results are discussed in terms of the influence of hypnotic emotional numbing at a preattentive stage of processing.

In a pilot investigation of reality monitoring in hypnosis, 10 high and 10 low hypnotizable participants were administered a hypnotic suggestion to hallucinate a visual shape on a wall. For half the participants, an image was subtly projected onto the wall at the commencement of the suggestion and then subsequently removed. For the remaining participants, the projected image was initially absent and subsequently projected. Participants completed ratings of belief in the suggestion during hypnosis and also provided subjective reports of the suggestion during a subsequent Experiential Analysis Technique session. High hypnotizable participants who had the projected image introduced at the end of the suggestion provided comparable belief ratings when the image was present and absent. In contrast, highs who had the projected image presented first reported less belief when the image was absent than when it was present. Low hypnotizable participants rated the hallucination more strongly when the image was projected than when it was not projected. These pilot data are discussed in terms of developing a paradigm to objectively index the perceived reality of hypnotically suggested experiences.

Although there is converging evidence that posttraumatic stress disorder (PTSD) is associated with higher levels of hypnotizability, there are no studies concerning the stability of hypnotizability levels following trauma. Acutely traumatized participants with acute stress disorder (N = 45) were administered the Stanford Hypnotic Clinical Scale (SHCS) within 4 weeks of their trauma. Participants were subsequently administered a brief cognitive-behavior therapy program. Six months after treatment, participants were re-assessed with the SHCS. Although SHCS scores were generally stable (r = .47), two thirds of participants responded differently across the 2 assessments. Increased SHCS scores at the second assessment were correlated with elevated PTSD avoidance scores. This finding suggests that elevated hypnotizability in PTSD populations may not be entirely stable and may be associated with specific PTSD responses.

Two experiments investigated the reality attributed to hypnotic suggestion through subtle projection of a visual image during simultaneous suggestion for a visual hallucination that resembled the projected image. In Experiment 1, high and low hypnotizable participants were administered either a hypnotic induction or wake instructions, given a suggestion to hallucinate a shape, and then the projected image was subsequently introduced. Although highs in both conditions rated the projected image more vividly than lows, highs in the hypnosis (but not wake) condition made comparable reality ratings when the projected image was absent and present. In Experiment 2, high hypnotizable participants were administered a suggestion to see a shape on a wall. For half the participants the suggested image was projected on the wall and then removed, and for half the projection was initially absent and then introduced. Participants who had the projection absent and then present reported comparable reality and vividness ratings when the projection was absent and present. These findings indicate that elevated hypnotizability and hypnosis are associated with attributions of external reality to suggested experiences.

This study compared 20 real, hypnotized and 20 simulating, unhypnotized participants who were administered a hypnotic induction and then presented with emotionally distressing and neutral visual images. Half were administered a hypnotic suggestion for emotional numbing. Reals and simulators who received the emotional numbing suggestion reported comparably less responsivity to distressing stimuli than others. Whereas emotionally numb reals displayed little change in electromyographic (EMG) activity during the distressing stimuli, simulators displayed marked reduction in EMG activity. Reals (not simulators) displayed a dissociation between their affective response and awareness of the negative content of the stimuli following the numbing suggestion.

A suggestion for hypnotic color blindness was investigated by administering a reverse Stroop color-naming task. Prior to the suggestion for color blindness, participants learned associations between color names and shapes. Following the color blindness suggestion, participants were required to name the shapes when they appeared in colors that were either congruent or incongruent with the learned associations. The 18 high hypnotizable participants who passed the suggestion were slower to name (a) shapes in which the color name was incongruent with the color in which it was printed, (b) "unseen" rather than "seen" shapes, and (c) color-incongruent shapes that were printed in the color in which they were "color-blind." These patterns are discussed in terms of potential cognitive and social mechanisms that may mediate responses to hypnotic color blindness.

This article focuses on dissociations between explicit and implicit expressions of memory during posthypnotic amnesia (PHA). Despite evidence of such dissociations, experimental design in this area has not always been consistent with contemporary memory research. Within a paradigm that aimed for conceptual and methodological clarity, we presented 40 high and 38 low hypnotizable individuals with a word list either before or during hypnosis, gave them a PHA suggestion for the word list, and tested them on explicit and implicit memory tasks. In the absence of conscious recollection, highs showed equivalent levels of priming (perceptual and semantic) to lows. However, when analysis focused only on those highs who remained amnesic after the implicit memory tasks, we confirmed perceptual, but not semantic, priming. These findings highlight the impact of methodological choices on theoretical interpretations of memory performance following a suggestion for PHA.

This study investigated the utility of a hypnotic suggestion to inhibit emotional response. High and low hypnotizable participants (N = 53) were administered a hypnotic induction, and half the participants were then administered a suggestion for emotional numbing. Participants were then presented with slides depicting neutral or disfigured faces. Participants who received the emotional numbing suggestion reported less responsivity to the disfigured faces than did those in the control condition, and this pattern was stronger for high than for low hypnotizable participants. Highs in the numbing condition displayed less overall distress in their facial expressions in response to the disfigured slides relative to those in the control condition. These findings suggest that hypnotic emotional numbing may be a useful paradigm in which to explore processes in emotion inhibition.

Objective: This study investigated the relationship between acute dissociative reactions to trauma and hypnotizability., Method: Acutely traumatized patients (N=61) with acute stress disorder, subclinical acute stress disorder (no dissociative symptoms), and no acute stress disorder were administered the Stanford Hypnotic Clinical Scale within 4 weeks of their trauma., Results: Although patients with acute stress disorder and patients with subclinical acute stress disorder displayed comparable levels of nondissociative psychopathology, acute stress disorder patients had higher levels of hypnotizability and were more likely to display reversible posthypnotic amnesia than both patients with subclinical acute stress disorder and patients with no acute stress disorder., Conclusions: The findings may be interpreted in light of a diathesis-stress process mediating trauma-related dissociation. People who develop acute stress disorder in response to traumatic experience may have a stronger ability to experience dissociative phenomena than people who develop subclinical acute stress disorder or no acute stress disorder.

This study investigated the impact of hypnotically induced mood on the specificity of autobiographical memory. High (n = 24) and low (n = 21) hypnotizable participants were administered a hypnotic induction for sad, neutral, or happy mood and were asked to retrieve specific autobiographical memories in response to positive and negative cue words. Whereas high hypnotizable participants in the sad condition provided fewer specific memories in response to positive rather than negative cues, those in the neutral and happy conditions responded similarly to positive and negative cues. Findings suggest that impaired recall of specific memories may be mediated by state factors associated with sad mood. These results point to the utility of hypnotic mood induction as a means to experimentally investigate the relationship between mood and autobiographical memory.

The impact of a suggestion for posthypnotic amnesia on material learned either before or during hypnosis was investigated across 2 experiments. In Experiment 1, very high, high, and low hypnotizable participants learned a word list either before or immediately after a hypnotic induction. During hypnosis, participants were given a suggestion for posthypnotic amnesia for the word list. After hypnosis, they were tested on recall, word-fragment, and word-recognition tasks. Experiment 2 replicated and extended Experiment 1 through application of the real-simulating paradigm. Across the 2 experiments, there was no difference in the performance of participants who learned the word list either before or during hypnosis. Although amnesia on direct memory measures was associated with high hypnotizability (Experiment 1), an explanation based on demand characteristics could not be excluded (Experiment 2). The implications of these findings for the use of post-hypnotic amnesia as a laboratory analog of disorders of autobiographical memory are discussed.

This case study investigated the utility of hypnosis to precipitate a seizure in a patient with refractory epilepsy. The patient was twice administered a hypnotic induction and a suggestion to age regress to a day when he was distressed and suffered repeated seizures. The patient did not respond to the first hypnotic suggestion; however, an epileptic seizure was observed in the second hypnotic session. Videorecording and subdural electroencephalograph recording confirmed that he suffered an epileptic seizure. Postexperimental inquiry revealed that the patient used deliberate cognitive strategies to avoid seizure onset in the first session but adopted a more constructive cognitive style in the second session. Findings are discussed in terms of emotions, hypnosis, and cognitive style as mediating factors in the experimental precipitation of epileptic seizures.

In 2 experiments we investigated trance logic, or the tolerance of logical incongruity, in age regression and hallucination. Experiment 1 tested 21 hypnotizable and 19 unhypnotizable subjects in an application of the real-simulating model of hypnosis. Experiment 2 tested 26 high and 19 low imagery ability subjects in an adaptation of the model to the imagination context. Subjects' experiences were investigated through the experiential analysis technique. More real than simulating subjects displayed trance logic during age regression, but they did not differ on the major measures of trance logic during hallucination. This pattern of responding occurred in both the hypnosis and the imagination contexts. Subjects' comments suggested that completeness of and belief in age regression or hallucination may play some role in trance logic. The importance of understanding trance logic from the subject's point of view is discussed.

Real, hypnotized and simulating, unhypnotized subjects were instructed to use either a constructive or a concentrative cognitive style when attempting to respond to a suggestion for hypnotic blindness; also, some subjects were administered the suggestion without any instructions about cognitive style. More reals who received the constructive rather than the concentrative instructions reported complete blindness; a similar number of simulators who received the different instructions reported complete blindness. Moreover, reals who received the constructive instruction reported a more rapidly developed belief in their blindness. The findings are discussed in terms of the relevance of cognitive style to subjects' reports of hypnotic blindness, and the possibility is considered that both reports of and belief in hypnotic blindness are determined in part by cognitive style.

Real hypnotizable Ss and simulating unhypnotizable Ss were administered a suggestion for either happiness, emotional neutrality, or sadness. The emotion was assessed through subjective and behavioral measures taken once before, twice during, and once after the emotion. Findings indicated that emotionally congruent changes occurred in both self-report and performance measures. Ss' physical sensations during the emotion were assessed on a 34-item self-report scale. It was demonstrated that Ss in the happy versus sad conditions reported different physical sensations; in particular, they reported different facial sensations. The responses of real hypnotizable Ss, however, were essentially paralleled by those of simulating unhypnotizable Ss. Therefore, the possibility exists that hypnotized Ss may have been responding on the basis of social demands. The findings are discussed in terms of the effects of the emotion suggestions, and the implications of real and simulating Ss displaying similar affective responses.

Examined whether performance on a spelling task would be influenced by visual information in the reported absence of hypnotized subjects' awareness of that information. Experiment 1 visually presented uncommon spellings of homophones to subjects before and during a suggestion for hypnotic blindness, and subsequently tested subjects' spelling of the homophones. Words presented during hypnotic blindness influenced subjects' spelling performance. Subjects' attributions of their performance did not involve awareness of the homophones. Experiment 2 used the nonexperiment methodology to examine the impact of demand characteristics and indicated that the performance attributions of subjects of Experiment 1 could not be explained in these terms. The discussion focuses on implicit perception in hypnotic blindness and on the relevance of attributions about behavioral performance on hypnotic phenomena.

This research examined the influence of visual information on a decision task that subjects were administered during hypnotically suggested blindness. Real, hypnotizable subjects and simulating, unhypnotizable subjects were tested in two experiments. Experiment 1 focused on behavioral responses, and Experiment 2 focused on experiential reactions. In both experiments, the findings indicated that the behavioral responses of reals were influenced by visual information despite their reported blindness. The behavioral responses of reals and simulators were essentially similar. The experiential data in Experiment 2 provided information about the phenomenal nature of subjects' reported blindness. The experimental reactions of reals and simulators were essentially different. The research is discussed in terms of the issues that need to be considered in the development of a model of hypnotic blindness.