Trauma and anxious attachment influence the relationship between suggestibility and dissociation: a moderated-moderation analysis

Introduction: Hypnotic suggestibility is elevated in the dissociative disorders but the relationship between dissociative tendencies and suggestibility in the general population seems to be constrained by additional factors. The diathesis-stress (DS) model stipulates that suggestibility interacts with trauma exposure to augment the propensity for dissociative states whereas the dual pathway to suggestibility (DPS) model proposes two developmental routes involving either dissociation preceded by trauma, or a healthy cognitive profile characterized by superior imagination. Methods: This study sought to discriminate between these partially competing accounts and further considered the moderating role of anxious attachment. 209 participants completed psychometric measures of dissociative tendencies, trauma, and attachment, and a behavioural measure of suggestibility. Results: In support of the DS model, trauma moderated the relationship between suggestibility and dissociation and, as predicted by the DPS model, dissociation moderated the relationship between trauma and suggestibility. Anxious attachment additionally moderated both effects. Model comparisons indicated that the DS model consistently provided a superior fit to the data. Further analyses showed that secure attachment independently predicted suggestibility, thereby supporting the non-dissociative pathway in the DPS model. Conclusions: These results suggest that high suggestibility confers vulnerability to dissociative states in individuals exposed to trauma and displaying an anxious attachment style

The induction of synaesthesia with chemical agents: A systematic review

Despite the general consensus that synaesthesia emerges at an early developmental stage and is only rarely acquired during adulthood, the transient induction of synaesthesia with chemical agents has been frequently reported in research on different psychoactive substances. Nevertheless, these effects remain poorly understood and have not been systematically incorporated. Here we review the known published studies in which chemical agents were observed to elicit synaesthesia. Across studies there is consistent evidence that serotonin agonists elicit transient experiences of synaesthesia. Despite convergent results across studies, studies investigating the induction of synaesthesia with chemical agents have numerous methodological limitations and little experimental research has been conducted. Cumulatively, these studies implicate the serotonergic system in synaesthesia and have implications for the neurochemical mechanisms underlying this phenomenon but methodological limitations in this research area preclude making firm conclusions regarding whether chemical agents can induce genuine synaesthesia

Pedunculopontine-Induced cortical decoupling as the neurophysiological locus of dissociation

Mounting evidence suggests an association between aberrant sleep phenomena and dissociative experiences. However, no wake-sleep boundary theory provides a compelling explanation of dissociation or specifies its physiological substrates. We present a theoretical account of dissociation that integrates theories and empirical results from multiple lines of research concerning the domain of dissociation and the regulation of rapid eye movement (REM) sleep. This theory posits that individual differences in the circuitry governing the REM sleep promoting Pedunculopontine Nucleus and Laterodorsal Tegmental Nucleus determine the degree of similarity in the cortical connectivity profiles of wakefulness and REM sleep. We propose that a latent trait characterized by elevated dissociative experiences emerges from the decoupling of frontal executive regions due to a REM sleep-like aminergic/cholinergic balance. The Pedunculopontine Induced Cortical Decoupling Account of Dissociation (PICDAD) suggests multiple fruitful lines of inquiry and provides novel insights

Variations in the sense of agency during hypnotic responding: Insights from latent profile analysis

The primary phenomenological feature of a response to hypnotic suggestion is the perception that a person is not the author of their actions and experiences. This distortion in volition during hypnotic responding, known as the classic suggestion effect, has the potential to illuminate the neurocognitive mechanisms underlying hypnosis and inform broader models of agency. Here, we sought to clarify interindividual differences in the patterns of agency that participants experience during hypnosis. We applied latent profile analysis, a finite mixture modeling method for partitioning participants into homogeneous classes, to participants’ responses to a standardized behavioral measure of hypnotic suggestibility and an experiential measure of sense of agency during hypnotic responding. The best fitting model suggested that there were 4 discrete response patterns: a low suggestible class, 2 medium suggestible classes, and 1 highly suggestible class. The 2 medium suggestible classes displayed nearly equivalent patterns of behavioral hypnotic responding but diverged in their experience of agency during hypnotic responding: 1 class experienced greater involuntariness during responding, whereas the other experienced greater effortlessness during responding. These results reinforce previous research highlighting differential patterns of hypnotic responding and complement work suggesting that there may be 2 or more phenomenologically distinct modes of hypnotic responding. They also have a number of implications for the measurement of hypnotic responding and for the use of low and medium suggestible individuals in experimental hypnosis research designs

Anomalous experiences are more prevalent among highly suggestible individuals who are also highly dissociative

Introduction: Predictive coding models propose that high hypnotic suggestibility confers a predisposition to hallucinate due to an elevated propensity to weight perceptual beliefs (priors) over sensory evidence. Multiple lines of research corroborate this prediction and demonstrate a link between hypnotic suggestibility and proneness to anomalous perceptual states. However, such effects might be moderated by dissociative tendencies, which seem to account for heterogeneity in high hypnotic suggestibility. We tested the prediction that the prevalence of anomalous experiences would be greater among highly suggestible individuals who are also highly dissociative. Methods: We compared high and low dissociative highly suggestible participants and low suggestible controls on multiple psychometric measures of anomalous experiences. Results: High dissociative highly suggestible participants reliably reported greater anomalous experiences than low dissociative highly suggestible participants and low suggestible controls, who did not significantly differ from each other. Conclusions: These results suggest a greater predisposition to experience anomalous perceptual states among high dissociative highly suggestible individuals

Using Adaptive Psychophysics to Identify the Neural Network Reset Time in Subsecond Interval Timing

State dependent network models of subsecond interval timing propose that duration is encoded in states of neuronal populations that need to reset prior to a novel timing operation in order to maintain optimal timing performance. Previous research has shown that the approximate boundary of this reset interval can be inferred by varying the interstimulus interval between two to-be-timed intervals. However, the estimated boundary of this reset interval is broad (250-500ms) and remains underspecified with implications for the characteristics of state dependent network dynamics subserving interval timing. Here we probed the interval specificity of this reset boundary by manipulating the interstimulus interval between standard and comparison intervals in two subsecond auditory duration discrimination tasks (100 and 200ms) and a control (pitch) discrimination task using adaptive psychophysics. We found that discrimination thresholds improved with the introduction of a 333ms interstimulus interval relative to a 250ms interstimulus interval in both duration discrimination tasks, but not in the control task. This effect corroborates previous findings of a breakpoint in the discrimination performance for subsecond stimulus interval pairs as a function of an incremental interstimulus delay but more precisely localizes the minimal interstimulus delay range. These results suggest that state dependent networks subserving subsecond timing require approximately 250-333ms for the network to reset in order to maintain optimal interval timing