Effects of Prehypnotic Instructions on Hypnotizability and Relationships Between Hypnotizability, Absorption, and Empathy

Comparative effects of hypnotic suggestion and imagery instruction on bodily awareness

Bodily awareness is informed by both sensory data and prior knowledge. Although misleading sensory signals have been repeatedly shown to affect bodily awareness, only scant attention has been given to the influence of cognitive variables. Hypnotic suggestion has recently been shown to impact visuospatial and sensorimotor representations of body-part size although the mechanisms subserving this effect are yet to be identified. Mental imagery might play a causal or facilitative role in this effect, as it has been shown to influence body awareness in previous studies. Nonetheless, current views ascribe only an epiphenomenal role to imagery in the implementation of hypnotic suggestions. This study compared the effects of hypnotic suggestion and imagery instruction for influencing the visuospatial and sensorimotor aspects of body-size representation. Both experimental manipulations produced significant increases (elongation) in both representations compared to baseline, although the effects were larger in the hypnotic suggestion condition. The effects of both manipulations were highly correlated across participants, suggesting overlapping mechanisms. Self-reports suggested that the use of voluntary imagery did not significantly contribute to the efficacy of either manipulation. Rather, top-down effects on body representations seem to be partly driven by response expectancies, spontaneous imagery, and hypnotic suggestibility in both conditions. These results are in line with current theories of suggestion and raise fundamental questions regarding the mechanisms driving the influence of cognition on body representations.

Prevalence of visual snow and relation to attentional absorption

Visual snow is a condition of unclear prevalence characterized by tiny flickering dots throughout the entire visual field. It appears to result from visual cortex hyperactivity and possibly correlates with propensity to be engrossed in sensory and imaginary experiences (absorption). The prevalence and correlates of visual snow, and emotional reactions to it, were explored in the general Portuguese population with three studies with online surveys. In Study 1, 564 participants were shown an animated graphic simulation of visual snow and asked to rate how frequently they have similar percepts on a scale anchored by 0% and 100% of their waking time. They also reported their degree of distress and fascination resulting from visual snow. Absorption was measured with the Modified Tellegen Absorption Scale. 44% of respondents reported they see visual snow at least 10% of the time, and 20% reported seeing it between 80% and 100% of the time. Similar to findings in clinical samples, the frequency of visual snow correlated with tinnitus frequency and entoptic phenomena, but not with ophthalmologic problems. It was confirmed that visual snow is related to absorption. Although distress caused by visual snow was generally absent or minimal in our samples, a substantial minority (28%) reported moderate to high levels of distress. High fascination with visual snow was reported by 9%. In Studies 2 and 3, visual snow was measured by means of verbal descriptions without graphic simulation (“visual field full of tiny dots of light” and “world seen with many dots of light”, respectively). The results were similar to those in Study 1, but seeing visual snow 80%-100% of the time was less frequent (6.5% in Study 2 and 3.6% in Study 3). Visual snow has been insufficiently investigated. More research is needed to uncover underlying neurophysiological mechanisms and psychological and behavioral correlates.

A Critical Review of Standardized Measures of Hypnotic Suggestibility

The most well-established finding gleaned from decades of experimental hypnosis research is that individuals display marked variability in responsiveness to hypnotic suggestions. Insofar as this variability impacts both treatment outcome in therapeutic applications of hypnosis as well as responsiveness to suggestions in experimental contexts, it is imperative that clinicians and researchers use robust measures of hypnotic suggestibility. The current paper critically evaluates contemporary measures of hypnotic suggestibility. After reviewing the most widely used measures, we identify multiple properties of these instruments that result in the loss of valuable information, including binary scoring and single-trial sampling, and hinder their utility, such as the inclusion of suboptimal suggestion content. The scales are not well-suited for contemporary research questions and have outlived their usefulness. We conclude by outlining ways in which the measurement of hypnotic suggestibility can be advanced.

Sex moderates the association between the COMT Val158Met single-nucleotide polymorphism and disorderliness facet of novelty seeking

Previous studies have shown inconsistent results regarding the effect of the Val¹⁵⁸Met polymorphism of the catechol-O-methyltransferase (COMT) gene on personality and cognition. Here, nonclinical Caucasian university students of Italian origin were administered the Temperament and Character Inventory-Revised, Tellegen Absorption Scale, Differential Attentional Processes Inventory, and Waterloo-Stanford Group Scale of Hypnotic Susceptibility. We found that the COMT Val¹⁵⁸Met polymorphism was significantly associated with the disorderliness facet of novelty seeking (NS4) and that sex was a moderator of this association. Females with the Met/Met genotype showed higher NS4 scores compared to those with the Val/Met and Val/Val genotypes. No significant genotype effect was found for males. Additionally, we failed to find a significant effect of the COMT gene on attention and hypnotic suggestibility measures. These results provide further evidence for a sex-specific influence on the gene-behaviour associations.