The ability to respond to hypnotic suggestibility (hypnotizability) is a stable trait which can be measured in a standardized 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 retest 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 hypnotizability, which reflects changes in conscious experience and presents practical and theoretical advantages over existing scales.

Hypnosis and hypnotic suggestions are gradually gaining popularity within the consciousness community as established tools for the experimental manipulation of illusions of involuntariness, hallucinations and delusions. However, hypnosis is still far from being a widespread instrument; a crucial hindrance to taking it up is the amount of time needed to invest in identifying people high and low in responsiveness to suggestion. In this study, we introduced an online assessment of hypnotic response and estimated the extent to which the scores and psychometric properties of an online screening differ from an offline one. We propose that the online screening of hypnotic response is viable as it reduces the level of responsiveness only by a slight extent. The application of online screening may prompt researchers to run large-scale studies with more heterogeneous samples, which would help researchers to overcome some of the issues underlying the current replication crisis in psychology.

Rationale Interoception is the signalling, perception, and interpretation of internal physiological states. Many mental disorders associated with changes of interoception, including depressive and anxiety disorders, are treated with selective serotonin reuptake inhibitors (SSRIs). However, the causative link between SSRIs and interoception is not yet clear. Objectives To ascertain the causal effect of acute changes of serotonin levels on cardiac interoception. Methods Using a within-participant placebo-controlled design, forty-seven healthy human volunteers (31 female, 16 male) were tested on and off a 20 mg oral dose of the commonly prescribed SSRI, citalopram. Participants made judgements on the synchrony between their heartbeat and auditory tones and then expressed confidence in each judgement. We measured three types of interoceptive cognition. Results Citalopram increased cardiac interoceptive insight, measured as correspondence of self-reported confidence to the likelihood that interoceptive judgements were actually correct. This effect was driven by enhanced confidence for correct interoceptive judgements and was independent of measured cardiac and reported subjective effects of the drug. Conclusions An acute change of serotonin levels can increase insight into the reliability of inferences made from cardiac interoceptive sensations.

Interoception is the signaling, perception, and interpretation of internal physiological states. A causal link between serotonin and interoception was tested by a within-participant, crossover, placebo-controlled study. Forty-seven healthy human volunteers were tested on and off a 20mg oral dose of the selective serotonin reuptake inhibitor (SSRI) citalopram. For each randomly ordered session, participants made a series of judgements about the synchrony of their heartbeat to auditory tones and expressed confidence in each judgement. Citalopram enhanced insight into the likelihood that a correct interoceptive judgement occurred, driven primarily by increased confidence in correct judgements. This effect was independent of measured physiological and subjective effects of the drug and greater than a null effect on insight into exclusively exteroceptive performance on a visual task. This finding provides a foundation for considering effects of serotonin on cognition, emotion, and behavior in terms of higher order processing of interoceptive events.

Background: Gathering and evaluating information leads to better decisions, but often at cost. The balance between information seeking and exploitation features in neurodevelopmental, mood, psychotic and substance-related disorders. Serotonin’s role has been highlighted by experimental reduction of its precursor, tryptophan. Aims: We tested the boundaries and applicability of this role by asking whether changes to information sampling would be observed following acute doses of serotonergic and catecholaminergic clinical treatments. We used a variant of the Information Sampling Task (IST) to measure how much information a person requires before they make a decision. This task allows participants to sample information until satisfied to make a choice. Methods: In separate double-blind placebo-controlled experiments, we tested 27 healthy participants on/off 20 mg of the serotonin reuptake inhibitor (SRI) citalopram, and 22 participants on/off 40 mg of the noradrenergic reuptake inhibitor atomoxetine. The IST variant minimised effects of temporal impulsivity and loss aversion. Analyses used a variety of participant prior expectations of sampling spaces in the IST, including a new prior that accounts for learning of likely states across trials. We analysed behaviour by a new method that also accounts for baseline individual differences of risk preference. Results: Baseline preferences demonstrated risk aversion. Citalopram decreased the expected utility of choices and probability of being correct based on informational content of samples collected, suggesting participants collected less useful information before making a choice. Atomoxetine did not influence information seeking. Conclusion: Acute changes of serotonin activity by way of a single SRI dose alter information-seeking behaviour.

There exist reliable and stable trait differences in the ability to control phenomenology in response to imaginative suggestion. Hypnotizability scales measure response to imaginative suggestion within a hypnotic context. Because hypnotizability has recently been shown to predict measures of experiential change in psychological experiments (e.g., the rubber hand illusion), there is a need for easy-to-use screening tools which are accessible to researchers with little or no background in hypnosis or imaginative suggestion research. The SWASH is a time-efficient group hypnotizability scale which can be administered to up to 50 participants simultaneously. Here we present norms from an undergraduate sample for a recorded version delivered by a computer program alongside norms for a live presentation. Reliability, validity, and mean scores are similar across the two presentations. Computer delivery of a prerecorded script provides a simple tool to rapidly screen for hypnotizability in large groups for researchers with no prior experience of hypnosis research.

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