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.

Hypnotic suggestion: opportunities for cognitive neuroscience.

Hypnosis uses the powerful effects of attention and suggestion to produce, modify and enhance a broad range of subjectively compelling experiences and behaviours. For more than a century, hypnotic suggestion has been used successfully as an adjunctive procedure to treat a wide range of clinical conditions. More recently, hypnosis has attracted a growing interest from a cognitive neuroscience perspective. Recent studies using hypnotic suggestion show how manipulating subjective awareness in the laboratory can provide insights into brain mechanisms involved in attention, motor control, pain perception, beliefs and volition. Moreover, they indicate that hypnotic suggestion can create informative analogues of clinical conditions that may be useful for understanding these conditions and their treatments.

Suggestions to Reduce Clinical Fibromyalgia Pain and Experimentally Induced Pain Produce Parallel Effects on Perceived Pain but Divergent Functional MRI-Based Brain Activity.

OBJECTIVE: Hypnotic suggestion is an empirically validated form of pain control; however, the underlying mechanism remains unclear. METHODS: Thirteen fibromyalgia patients received suggestions to alter their clinical pain, and 15 healthy controls received suggestions to alter experimental heat pain. Suggestions were delivered before and after hypnotic induction with blood oxygen level-dependent (BOLD) activity measured concurrently. RESULTS: Across groups, suggestion produced substantial changes in pain report (main effect of suggestion, F2, 312 = 585.8; p < .0001), with marginally larger changes after induction (main effect of induction, F1, 312 = 3.6; p = .060). In patients, BOLD response increased with pain report in regions previously associated with pain, including thalamus and anterior cingulate cortex. In controls, BOLD response decreased with pain report. All changes were greater after induction. Region-of-interest analysis revealed largely linear patient responses with increasing pain report. Control responses, however, were higher after suggestion to increase or decrease pain from baseline. CONCLUSIONS: Based on behavioral report alone, the mechanism of suggestion could be interpreted as largely similar regardless of the induction or type of pain experience. The functional magnetic resonance imaging data, however, demonstrated larger changes in brain activity after induction and a radically different pattern of brain activity for clinical pain compared with experimental pain. These findings imply that induction has an important effect on underlying neural activity mediating the effects of suggestion, and the mechanism of suggestion in patients altering clinical pain differs from that in controls altering experimental pain. Patient responses imply that suggestions altered pain experience via corresponding changes in pain-related brain regions, whereas control responses imply suggestion engaged cognitive control.

The relationship between different types of dissociation and psychosis-like experiences in a non-clinical sample.

This study investigated whether detachment-type dissociation, compartmentalisation-type dissociation or absorption was most strongly associated with psychosis-like experiences in the general population. Healthy participants (N=215) were tested with the Dissociative Experiences Scale (DES, for detachment-related dissociative experiences); the Harvard Group Scale of Hypnotic Susceptibility (HGSHS: A, for dissociative compartmentalisation); the Tellegen Absorption Scale (TAS, for non-clinical 'functional' dissociative experience); and two measures of psychotic-like experiences, the 21-item Peters et al. Delusions Inventory (PDI-21) and the Cardiff Anomalous Perceptions Scale (CAPS). In multiple regression analyses, DES and TAS but not HGSHS: A scores were found to be significantly associated with PDI-21 and CAPS overall scores. A post hoc hierarchical cluster analysis checking for cluster overlap between DES and CAPS items, and the TAS and CAPS items showed no overlap between items on the DES and CAPS and minimal overlap between TAS and CAPS items, suggesting the scales measure statistically distinct phenomena. These results show that detachment-type dissociation and absorption, but not compartmentalisation-type dissociation are significantly associated with psychosis-like experiences in a non-clinical population.

Hypnosis and suggestion as interventions for functional neurological disorder: A systematic review.

OBJECTIVE: Functional neurological disorder (FND) involves the presence of neurological symptoms that cannot be explained by neurological disease. FND has long been linked to hypnosis and suggestion, both of which have been used as treatments. Given ongoing interest, this review examined evidence for the efficacy of hypnosis and suggestion as treatment interventions for FND. METHOD: A systematic search of bibliographic databases was conducted to identify group studies published over the last hundred years. No restrictions were placed on study design, language, or clinical setting. Two reviewers independently assessed papers for inclusion, extracted data, and rated study quality. RESULTS: The search identified 35 studies, including 5 randomised controlled trials, 2 non-randomised trials, and 28 pre-post studies. Of 1584 patients receiving either intervention, 1379 (87%) showed significant improvements, including many who demonstrated resolution of their symptoms in the short-term. Given the heterogeneity of interventions and limitations in study quality overall, more formal quantitative synthesis was not possible. CONCLUSIONS: The findings highlight longstanding and ongoing interest in using hypnosis and suggestion as interventions for FND. While the findings appear promising, limitations in the evidence base, reflecting limitations in FND research more broadly, prevent definitive recommendations. Further research seems warranted given these supportive findings.

Increased response time of primed associates following an "episodic" hypnotic amnesia suggestion: a case of unconscious volition.

Following a hypnotic amnesia suggestion, highly hypnotically suggestible subjects may experience amnesia for events. Is there a failure to retrieve the material concerned from autobiographical (episodic) memory, or is it retrieved but blocked from consciousness? Highly hypnotically suggestible subjects produced free-associates to a list of concrete nouns. They were then given an amnesia suggestion for that episode followed by another free association list, which included 15 critical words that had been previously presented. If episodic retrieval for the first trial had been blocked, the responses on the second trial should still have been at least as fast as for the first trial. With semantic priming, they should be faster. In fact, they were on average half a second slower. This suggests that the material had been retrieved but blocked from consciousness. A goal-oriented information processing framework is outlined to interpret these and related data.

Editing reality in the brain.

Recent information technologies such as virtual reality (VR) and augmented reality (AR) allow the creation of simulated sensory worlds with which we can interact. Using programming language, digital details can be overlaid onto displays of our environment, confounding what is real and what has been artificially engineered. Natural language, particularly the use of direct verbal suggestion (DVS) in everyday and hypnotic contexts, can also manipulate the meaning and significance of objects and events in ourselves and others. In this review, we focus on how socially rewarding language can construct and influence reality. Language is symbolic, automatic and flexible and can be used to augment bodily sensations e.g. feelings of heaviness in a limb or suggest a colour that is not there. We introduce the term 'suggested reality' (SR) to refer to the important role that language, specifically DVS, plays in constructing, maintaining and manipulating our shared reality. We also propose the term edited reality to encompass the wider influence of information technology and linguistic techniques that results in altered subjective experience and review its use in clinical settings, while acknowledging its limitations. We develop a cognitive model indicating how the brain's central executive structures use our personal and linguistic-based narrative in subjective awareness, arguing for a central role for language in DVS. A better understanding of the characteristics of VR, AR and SR and their applications in everyday life, research and clinical settings can help us to better understand our own reality and how it can be edited.

Dissociation in hysteria and hypnosis: evidence from cognitive neuroscience.

Jean-Martin Charcot proposed the radical hypothesis that similar brain processes were responsible for the unexplained neurological symptoms of 'hysteria', now typically diagnosed as 'conversion disorder' or 'dissociative (conversion) disorder', and the temporary effects of hypnosis. While this idea has been largely ignored, recent cognitive neuroscience studies indicate that (i) hypnotisability traits are associated with a tendency to develop dissociative symptoms in the sensorimotor domain; (ii) dissociative symptoms can be modelled with suggestions in highly hypnotisable subjects; and (iii) hypnotic phenomena engage brain processes similar to those seen in patients with symptoms of hysteria. One clear theme to emerge from the findings is that 'symptom' presentation, whether clinically diagnosed or simulated using hypnosis, is associated with increases in prefrontal cortex activity suggesting that intervention by the executive system in both automatic and voluntary cognitive processing is common to both hysteria and hypnosis. Nevertheless, while the recent literature provides some compelling leads into the understanding of these phenomena, the field still lacks well controlled systematically designed studies to give a clear insight into the neurocognitive processes underlying dissociation in both hysteria and hypnosis. The aim of this review is to provide an agenda for future research.

Using hypnosis to gain insights into healthy and pathological cognitive functioning.

The demonstration that hypnotic suggestion can inhibit word/colour Stroop highlights one of the benefits of using hypnosis to explore cognitive psychology and in particular attentional processes. The compelling results using a rigorous design have particular relevance for the presumed automaticity of some forms of information processing. Moreover the results support the potential that hypnotic suggestion offers for creating clinically informed analogues of relevant psychological and neuropsychological conditions. As with all novel research, the results of Raz and Campbell raise further operational and theoretical questions, relating in this case to the use of hypnotic, post-hypnotic and non-hypnotic suggestion and the utility of existing measures of hypnotizability.

Giving Up on Consciousness as the Ghost in the Machine.

Consciousness as used here, refers to the private, subjective experience of being aware of our perceptions, thoughts, feelings, actions, memories (psychological contents) including the intimate experience of a unified self with the capacity to generate and control actions and psychological contents. This compelling, intuitive consciousness-centric account has, and continues to shape folk and scientific accounts of psychology and human behavior. Over the last 30 years, research from the cognitive neurosciences has challenged this intuitive social construct account when providing a neurocognitive architecture for a human psychology. Growing evidence suggests that the executive functions typically attributed to the experience of consciousness are carried out competently, backstage and outside subjective awareness by a myriad of fast, efficient non-conscious brain systems. While it remains unclear how and where the experience of consciousness is generated in the brain, we suggested that the traditional intuitive explanation that consciousness is causally efficacious is wrong-headed when providing a cognitive neuroscientific account of human psychology. Notwithstanding the compelling 1st-person experience (inside view) that convinces us that subjective awareness is the mental curator of our actions and thoughts, we argue that the best framework for building a scientific account is to be consistent with the biophysical causal dependency of prior neural processes. From a 3rd person perspective, (outside view), we propose that subjective awareness lacking causal influence, is (no more) than our experience of being aware, our awareness of our psychological content, knowing that we are aware, and the belief that that such experiences are evidence of an agentive capacity shared by others. While the human mind can be described as comprising both conscious and nonconscious aspects, both ultimately depend on neural process in the brain. In arguing for the counter-intuitive epiphenomenal perspective, we suggest that a scientific approach considers all mental aspects of mind including consciousness in terms of their underlying, preceding (causal) biological changes, in the realization that most brain processes are not accompanied by any discernible change in subjective awareness.

The neurochemistry of hypnotic suggestion.

A diverse array of studies has been devoted to understanding the neurochemical systems supporting responsiveness to hypnotic suggestions, with implications for experimental and clinical applications of hypnosis. However, this body of research has only rarely been integrated and critically evaluated and the prospects for the reliable pharmacological manipulation of hypnotic suggestibility remain poorly understood. Here we draw on pharmacological, genotyping, neuroimaging, and electrophysiological research to synthesize current knowledge regarding the potential role of multiple widely-studied neurochemicals in response to suggestion. Although we reveal multiple limitations with this body of evidence, we identify converging results implicating different neurochemical systems in response to hypnotic suggestion. We conclude by assessing the extent to which different results align or diverge and outline multiple avenues for future research. Elucidating the neurochemical systems underlying response to suggestion has the potential to significantly advance our understanding of suggestion.

Hypnotic suggestion and cognitive neuroscience.

The growing acceptance of consciousness as a legitimate field of enquiry and the availability of functional imaging has rekindled research interest in the use of hypnosis and suggestion to manipulate subjective experience and to gain insights into healthy and pathological cognitive functioning. Current research forms two strands. The first comprises studies exploring the cognitive and neural nature of hypnosis itself. The second employs hypnosis to explore known psychological processes using specifically targeted suggestions. An extension of this second approach involves using hypnotic suggestion to create clinically informed analogues of established structural and functional neuropsychological disorders. With functional imaging, this type of experimental neuropsychopathology offers a productive means of investigating brain activity involved in many symptom-based disorders and their related phenomenology.

UNITED KINGDOM NORMS FOR THE HARVARD GROUP SCALE OF HYPNOTIC SUSCEPTIBILITY, FORM A.

The Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A), is widely used as a measure of suggestibility to screen participants for research purposes. To date, there have been a number of normative studies of the HGSHS:A, the majority of which originate from Western countries. The outcomes of these Western studies are summarized, and variations in methodologies are described and discussed. Also reported are the psychometric properties of the HGSHS:A in a large contemporary United Kingdom (UK) sample. Overall, these UK results are consistent with the earlier Western norms studies in terms of response distribution and item difficulty, with only minor differences. The continued use of HGSHS:A as a screening procedure is supported, particularly if corrected for response subjectivity/involuntariness and with revised amnesia scoring. The HGSHS:A is also important as a potential measure of the broader trait of direct verbal suggestibility.

Hypnotic depth and response to suggestion under standardized conditions and during FMRI scanning.

Hypnosis is a potentially valuable cognitive tool for neuroimaging studies. However, understandable concern that Magnetic Resonance Imaging (MRI) in particular may adversely affect hypnotic procedures remains. Measurements of hypnotic depth and responsiveness to suggestions were taken using a standardized procedure that met all the requirements for functional MRI (fMRI). Testing outside the scanning environment showed reliable and stable changes in subjective hypnotic depth, with no carryover once the hypnosis had been terminated. Within-subject comparisons showed that the magnitude and pattern of these changes and the degree of responsiveness to hypnotic suggestion were not discernibly affected by the fMRI environment. It is concluded that hypnosis can be employed as a discrete and reliable cognitive tool within fMRI neuroimaging settings.

Chasing the Rainbow: The Non-conscious Nature of Being.

Despite the compelling subjective experience of executive self-control, we argue that "consciousness" contains no top-down control processes and that "consciousness" involves no executive, causal, or controlling relationship with any of the familiar psychological processes conventionally attributed to it. In our view, psychological processing and psychological products are not under the control of consciousness. In particular, we argue that all "contents of consciousness" are generated by and within non-conscious brain systems in the form of a continuous self-referential personal narrative that is not directed or influenced in any way by the "experience of consciousness." This continuously updated personal narrative arises from selective "internal broadcasting" of outputs from non-conscious executive systems that have access to all forms of cognitive processing, sensory information, and motor control. The personal narrative provides information for storage in autobiographical memory and is underpinned by constructs of self and agency, also created in non-conscious systems. The experience of consciousness is a passive accompaniment to the non-conscious processes of internal broadcasting and the creation of the personal narrative. In this sense, personal awareness is analogous to the rainbow which accompanies physical processes in the atmosphere but exerts no influence over them. Though it is an end-product created by non-conscious executive systems, the personal narrative serves the powerful evolutionary function of enabling individuals to communicate (externally broadcast) the contents of internal broadcasting. This in turn allows recipients to generate potentially adaptive strategies, such as predicting the behavior of others and underlies the development of social and cultural structures, that promote species survival. Consequently, it is the capacity to communicate to others the contents of the personal narrative that confers an evolutionary advantage-not the experience of consciousness (personal awareness) itself.

Brain mechanisms for loss of awareness of thought and movement.

Loss or reduction of awareness is common in neuropsychiatric disorders and culturally influenced dissociative phenomena but the underlying brain mechanisms are poorly understood. fMRI was combined with suggestions for automatic writing in 18 healthy highly hypnotically suggestible individuals in a within-subjects design to determine whether clinical alterations in awareness of thought and movement can be experimentally modelled and studied independently of illness. Subjective ratings of control, ownership, and awareness of thought and movement, and fMRI data were collected following suggestions for thought insertion and alien control of writing movement, with and without loss of awareness. Subjective ratings confirmed that suggestions were effective. At the neural level, our main findings indicated that loss of awareness for both thought and movement during automatic writing was associated with reduced activation in a predominantly left-sided posterior cortical network including BA 7 (superior parietal lobule and precuneus), and posterior cingulate cortex, involved in self-related processing and awareness of the body in space. Reduced activity in posterior parietal cortices may underlie specific clinical and cultural alterations in awareness of thought and movement. Clinically, these findings may assist development of imaging assessments for loss of awareness of psychological origin, and interventions such as neurofeedback.

Are there two qualitatively distinct forms of dissociation? A review and some clinical implications.

This review aims to clarify the use of the term 'dissociation' in theory, research and clinical practice. Current psychiatric definitions of dissociation are contrasted with recent conceptualizations that have converged on a dichotomy between two qualitatively different phenomena: 'detachment' and 'compartmentalization'. We review some evidence for this distinction within the domains of phenomenology, factor analysis of self-report scales and experimental research. Available evidence supports the distinction but more controlled evaluations are needed. We conclude with recommendations for future research and clinical practice, proposing that using this dichotomy can lead to clearer case formulation and an improved choice of treatment strategy. Examples are provided within Depersonalization Disorder, Conversion Disorder and Posttraumatic Stress Disorder (PTSD).

The functional anatomy and connectivity of thought insertion and alien control of movement.

Alien control phenomena are symptoms reported by patients with schizophrenia whereby feelings of control and ownership of thoughts and movements are lost. Comparable alien control experiences occur in culturally influenced dissociative states. We used fMRI and suggestions for automatic writing in highly hypnotically suggestible individuals to investigate the neural underpinnings of alien control. Targeted suggestions selectively reduced subjective ratings of control and ownership for both thought and movement. Thought insertion (TI) was associated with reduced activation of networks supporting language, movement, and self-related processing. In contrast, alien control of writing movement was associated with increased activity of a left-lateralised cerebellar-parietal network and decreased activity in brain regions involved in voluntary movement, including sensory-motor hand areas and the thalamus. Both experiences involved a reduction in activity of left supplementary motor area (SMA) and were associated with altered functional connectivity (FC) between SMA and brain regions involved in language processing and movement implementation. Collectively these results indicate the SMA plays a central role in alien control phenomena as a high level executive system involved in the sense that we control and own our thoughts and movements.

Performance of Decorticated Rats on Fixed Interval and Fixed Time Schedules.

Rats with neocortex totally removed (decorticates), rats with hippocampal lesions (hippocampals), and their surgical controls, were trained on a fixed interval (FI) 40 s schedule, where the first bar-press response made more than 40 s after a previous reinforcement was rewarded. The decorticates and hippocampals adopted similar patterns of behaviour to the control groups through there were between-group differences in the details of performance. Compared to controls the hippocampals showed shorter post-reinforcement pauses and faster overall rates of responding, whilst the reverse was true of the decorticates. Some of this performance difference in the decorticates was attributed to difficulty in retrieving and consuming solid food reinforcement. The performance of the decorticates and hippocampals, as reflected by the post-reinforcement pause, response distribution and running rate as a function of post-reinforcement pause duration, suggests that timing remains operational in both groups. The differences in response profiles between the two experimental groups, however, indicate that hippocampus and neocortex probably make independent contributions to performance in this situation. The decorticates and their control group were later transferred from the FI to a response-independent fixed time (FT) 40 s schedule. Both groups then returned to the former FI 40 s schedule. The decorticates adjusted their behaviour to the different schedules in the same way as the control animals. The results overall are consistent with previous findings that decortication does not abolish normal patterns of operant learning and extends them to include temporal schedules.