Selective effects of serotonin on choices to gather more information

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

A single oral dose of citalopram increases interoceptive insight in healthy volunteers

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

Expressing unconscious general knowledge using Chevreul’s pendulum

Can unconscious knowledge be elicited by ideomotor action when the knowledge fails to be elicited by verbal reports? Using an Ouija board, previous research found ideomotor action produced substantial accuracy for general knowledge questions previously rated as pure “guesses,” and for which later verbal reports produced accuracy close to chance. We replicated the procedure substituting Chevreul’s pendulum rather than an Ouija board. We found that questions whose answer was previously rated as a guess, were answered equally well and at about chance levels by ideomotor action and verbal responses. Thus, one cannot presume that ideomotor action rather than verbal report will allow greater knowledge to be expressed in any particular context, including therefore the hypnotherapy one. An ideomotor action may elicit only conscious knowledge. Further research is recommended to clarify this important issue

Expressing unconscious general knowledge using Chevreul’s pendulum

Can unconscious knowledge be elicited by ideomotor action when the knowledge fails to be elicited by verbal reports? Using a Ouija board, Gauchou et al. (2012), found ideomotor action produced substantial accuracy for general knowledge questions previously rated as pure “guesses”, and for which later verbal reports produced accuracy close to chance. We replicated the procedure substituting Chevreul’s pendulum rather than a Ouija board. We found that questions whose answer was previously rated as a guess, were answered equally well and at about chance levels by ideomotor action and verbal responses. Thus, one cannot presume that ideomotor action rather than verbal report will allow greater knowledge to be expressed in any particular context, including therefore the hypnotherapy one. An ideomotor action may elicit only conscious knowledge. Further research is recommended to clarify this important issue

Computer vs live delivery of the Sussex Waterloo Scale of Hypnotisability (SWASH).

There exist reliable and stable trait differences in the ability to control phenomenology in response to imaginative suggestion. Hypnotisability scales measure response to imaginative suggestion within a hypnotic context. Because hypnotisability 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 hypnotisability 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 pre-recorded script provides a simple tool to rapidly screen for hypnotisability in large groups for researchers with no prior experience of hypnosis research