The Sussex-Waterloo Scale of hypnotisability (SWASH): measuring capacity or altering conscious experience

The ability to respond to hypnotic suggestibility (hypnotisability) is a stable trait which can be measured in a standardised procedure consisting of a hypnotic induction and a series of hypnotic suggestions. The SWASH is a 10-item adaptation of an established scale, the Waterloo-Stanford Group C Scale of Hypnotic Suggestibility (WSGC). Development of the SWASH was motivated by three distinct aims: to reduce required screening time, to provide an induction which more accurately reflects current theoretical understanding and to supplement the objective scoring with experiential scoring. Screening time was reduced by shortening the induction, removing two suggestions which may cause distress (dream and age regression) and by modifications which allow administration in lecture theatres, so that more participants can be screened simultaneously. Theoretical issues were addressed by removing references to sleep, absorption and eye fixation and closure. Data from 418 participants at the University of Sussex and the Lancaster University are presented, along with data from 66 participants who completed a re-test screening. The subjective and objective scales were highly correlated. The subjective scale showed good reliability and objective scale reliability was comparable to the WSGC. The addition of subjective scale responses to the post-hypnotic suggestion (PHS) item suggested a high probability that responses to PHS are inflated in WSGC screening. The SWASH is an effective measure of hypnotisability, which reflects changes in conscious experience and presents practical and theoretical advantages over existing scales

The Existence of a Hypnotic State Revealed by Eye Movements

Hypnosis has had a long and controversial history in psychology, psychiatry and neurology, but the basic nature of hypnotic phenomena still remains unclear. Different theoretical approaches disagree as to whether or not hypnosis may involve an altered mental state. So far, a hypnotic state has never been convincingly demonstrated, if the criteria for the state are that it involves some objectively measurable and replicable behavioural or physiological phenomena that cannot be faked or simulated by non-hypnotized control subjects. We present a detailed case study of a highly hypnotizable subject who reliably shows a range of changes in both automatic and volitional eye movements when given a hypnotic induction. These changes correspond well with the phenomenon referred to as the “trance stare” in the hypnosis literature. Our results show that this ‘trance stare’ is associated with large and objective changes in the optokinetic reflex, the pupillary reflex and programming a saccade to a single target. Control subjects could not imitate these changes voluntarily. For the majority of people, hypnotic induction brings about states resembling normal focused attention or mental imagery. Our data nevertheless highlight that in some cases hypnosis may involve a special state, which qualitatively differs from the normal state of consciousness

Discrete response patterns in the upper range of hypnotic suggestibility: A latent profile analysis

High hypnotic suggestibility is a heterogeneous condition and there is accumulating evidence that highly suggestible individuals may be comprised of discrete subtypes with dissimilar cognitive and phenomenological profiles. This study applied latent profile analysis to response patterns on a diverse battery of difficult hypnotic suggestions in a sample of individuals in the upper range of hypnotic suggestibility. Comparisons among models indicated that a four-class model was optimal. One class was comprised of very highly suggestible (virtuoso) participants, two classes included highly suggestible participants who were alternately more responsive to inhibitory cognitive suggestions or posthypnotic amnesia suggestions, and the fourth class consisted primarily of medium suggestible participants. These results indicate that there are discrete response profiles in high hypnotic suggestibility. They further provide a number of insights regarding the optimization of hypnotic suggestibility measurement and have implications for the instrumental use of hypnosis for the modeling of different psychological conditions

Differential patterns of spontaneous experiential response to a hypnotic induction: A latent profile analysis

A hypnotic induction produces different patterns of spontaneous experiences across individuals. The magnitude and characteristics of these responses covary moderately with hypnotic suggestibility, but also differ within levels of hypnotic suggestibility. This study sought to identify discrete phenomenological profiles in response to a hypnotic induction and assess whether experiential variability among highly suggestible individuals matches the phenomenological profiles predicted by dissociative typological models of high hypnotic suggestibility. Phenomenological state scores indexed in reference to a resting epoch during hypnosis were submitted to a latent profile analysis. The profiles in the derived four-class solution differed in multiple experiential dimensions and hypnotic suggestibility. Highly suggestible individuals were distributed across two classes that exhibited response patterns suggesting an inward attention subtype and a dissociative subtype. These results provide support for dissociative typological models of high hypnotic suggestibility and indicate that highly suggestible individuals do not display a uniform response to a hypnotic induction

Inhibition of retrieval in hypnotic amnesia:Dissociation by upper-alpha gating

Hypnotic amnesia is a functional dissociation from awareness during which information from specific neural processes is unavailable to consciousness. We test the proposal that changes in topographic patterns of cortical oscillations in upper-alpha (10–12 Hz) band selectively inhibit the recall of memories during hypnotic amnesia by blocking availability of locally processed information at specific points in retrieval. Participants were prescreened for high or low hypnotic susceptibility. Following hypnotic induction, participants were presented with a series of 60 face stimuli and were required to identify affective expressions. Participants received a suggestion for amnesia for these faces. They were then presented with a set of 30 old and 30 new faces and identified each as old or new. Amnesia suggestion was lifted and recall tested using the remaining 30 old faces and another 30 new faces. Exact Low Resolution Brain Electromagnetic Tomography source analyses are reported for 64 channel event-related electroencephalogram recorded from highs showing reversible amnesia to old faces. For high-susceptible participants, the amnesia suggestion significantly increased old faces wrongly identified while for low-susceptible participants amnesia suggestion increased the new faces wrongly identified. There were no differences between high- and low-susceptible participants following reversal of the suggestion. For previously seen faces which were wrongly identified, compared to new faces correctly identified, (late) evoked upper-alpha is significantly higher in right BA7 in a region implicated in top-down executive control to assist recall of visual information. Lagged nonlinear connectivity between cortical sources in upper-alpha in the same condition showed significantly increased connectivity between right BA34 (parahippocampal gyrus) and right BAs 7, 20 and 22. Integration between these regions is essential for recall of recent faces. During amnesia, spatial and temporal coordination of upper-alpha appears to suppress integrated functioning of these regions (hence recall). These patterns were absent after reversal of amnesia suggestion

Metacognition of intentions in mindfulness and hypnosis

In a famous series of experiments, Libet investigated the subjective timing of awareness of an intention to move, a task that can be considered a metacognitive judgement. The ability to strategically produce inaccurate metacognitions about intentions has been postulated to be central to the changes in judgements of agency common to all hypnotic responding. Therefore, differences in hypnotisability may be reflected in Libet’s measure. Specifically, the ability to sustain inaccurate judgements of agency displayed by highly hypnotisable people may result from their having coarser higher order representations of intentions. They therefore should report a delayed time of intention relative to less hypnotisable individuals. Conversely, mindfulness practice aims at accurate metacognition, including of intentions, and may lead to the development of finer grained higher order representations of intending. Thus, the long-term practice of mindfulness may produce an earlier judgement of the time of an intention. We tested these groups using Libet’s task, and found that, consistent with predictions, highly hypnotisable people reported a later time of intention than less hypnotisable people and meditators an earlier time than non-meditators. In a further two studies we replicated the finding that hypnotisable people report later awareness of a motor intention and additionally found a negative relationship between trait mindfulness and this measure. Based on these findings, we argue that hypnotic response and meditation involve opposite processes

Look into my eyes: pupillometry reveals that a post-hypnotic suggestion for word blindness reduces Stroop interference by marshalling greater effortful control

The mechanisms underpinning the apparently remarkable levels of cognitive and behavioural control following hypnosis and hypnotic suggestion are poorly understood. Numerous independent studies have reported that Stroop interference can be reduced following a post‐hypnotic suggestion that asks participants to perceive words as if made up of characters from a foreign language. This effect indicates that frontal executive functions can be more potent than is generally accepted and has been described as resulting from top‐down control not normally voluntarily available. We employed eye tracking and pupillometry to investigate whether the effect results from voluntary visuo‐attentional strategies (subtly looking away from the word to prevent optimal word processing), reduced response conflict but not overall conflict, Stroop effects being pushed from response selection to response execution (response durations) or increased proactive effortful control given enhanced contextual motivation (as indexed via pupil dilation). We replicated the reduction of Stroop interference following the suggestion despite removing any trials on which eye movements were not consistent with optimal word processing. Our data were inconclusive with regards to conflict type affected by the suggestion in the latency data, although preserved semantic conflict was evident in the pupil data. There was also no evidence of Stroop effects on response durations. However, we show that baseline corrected pupil sizes were larger following the suggestion indicating the socio‐cognitive context and experimental demands motivate participants to marshal greater effortful control

Comparison between REBT and Visual/Kinaesthetic Dissociation in the Treatment of Panic Disorder: An Empirical Study

The aim of this study was to test the efficacy of two brief treatment methods for panic disorder: Rational Emotive Behaviour Therapy (REBT) and Visual/Kinaesthetic Dissociation (VKD), neither of which have been the object of scientific enquiry. The study is a two-way between-groups pre-test/post-test experimental design with baseline and follow-up measures. An innovative four-session treatment protocol was developed for each treatment method. Eighteen participants in North-East Surrey, England, who responded to media advertisements for cognitive-behavioural treatment for panic disorder and who met Diagnostic and Statistical Manual of Mental Disorders criteria for panic disorder with or without agoraphobia were randomly assigned to either REBT or VKD. Pre-test/post-test changes in panic were measured using the ACQ, PASQ, and HADS scales and a global panic rating measure. At post-test there was a statistically significant improvement on all measures for both groups, which was maintained at one-month follow-up. Taking into consideration limitations such as the small sample size and a short follow-up period, implications of this study and recommendations for future research are discussed