High hypnotizability is associated with left-sided cerebral asymmetry, which could influence measurement of the Peripersonal Space (PPS). Right-handed participants with high (highs, n = 20), medium (mediums, n = 9), and low hypnotizability scores (lows, n = 20) performed the line bisection test on a computer screen automatically displaced at distances of 30, 60, and 90 cm from the subjects’ eyes. Highs’ results showed rightward bias of the bisection (Relative Error, RE) for all presentation distances. In contrast, in lows RE was displaced leftward at 30 cm and exhibited a progressive rightward shift at 60 and 90 cm, as occurs in the general population. Mediums’ RE values were intermediate between highs’ and lows’ values. Bisection Times (BT) were significantly longer in highs/mediums than in lows. Findings indicate that the highs’ bisection identifies PPS as if it was extrapersonal, but further studies should assess its functional characteristics. The highs/mediums longer BT suggest less efficient sensorimotor performance.
Research funded by University of Pisa (Fondi di Ateneo, 2013).
Earlier studies have shown hypnotizability-related postural effects of visual suppression and of leg and neck proprioceptive alteration. This study completes this investigation by demonstrating the postural effects of asymmetric tactile foot stimulation in standing participants with different hypnotizability scores. During this stimulation, body sway changed in medium-to-high more than in low-to-medium hypnotizable participants. Findings support the view that high hypnotizability is associated with higher vulnerability of posture to sensory alteration; together with earlier results, they suggest a role of the cerebellum in the observed hypnotizability-related differences and prompt investigation of cerebral structures and factors potentially responsible for both the cognitive and physiological aspects of hypnotizability.
The aim of this paper is to complement the recently revised American Psychological Association definition of hypnotizability. It (a) lists a few differences in sensorimotor integration between subjects with high and low hypnotizability scores in the ordinary state of consciousness and in the absence of suggestions; (b) proposes that hypnotizability-related cerebellar peculiarities may account for them; (c) suggests that the cerebellum could also be involved in cognitive aspects of hypnotizability; (d) explains why the information derived from studies of sensorimotor and cardiovascular aspects of hypnotizability may be relevant to its definition and useful in orienting further experimental research in the field of hypnosis.
The present study evaluated the heart-rate dynamics of subjects reporting decreased (responders) or paradoxically increased relaxation (nonresponders) at the end of a threatening movie. Heart-rate dynamics were characterized by indices extracted through recurrence quantification analysis (RQA) and detrended fluctuation analysis (DFA). These indices were studied as a function of a few individual characteristics: hypnotizability, gender, absorption, anxiety, and the activity of the behavioral inhibition and activation systems (BIS/BAS). Results showed that (a) the subjective experience of responsiveness is associated with the activity of the behavioral inhibition system and (b) a few RQA and DFA indices are able to capture the influence of cognitive-emotional traits, including hypnotizability, on the responsiveness to the threatening task.
In the general population, suppression of vision modulates body sway by increasing the center of pressure (CoP) velocity, while a light fingertip touch reduces the area of the CoP displacement in blindfolded subjects. This study assessed whether imagined fixation and fingertip touch differentially stabilize posture in subjects with high (highs) and low (lows) hypnotizability. Visual and tactile imageries were ineffective in lows. In highs, the effects of visual imagery could not be evaluated because the real information was ineffective; real tactile stimulation was effective only on velocity, but the imagery effects could not be definitely assessed owing to low effect size. The highs’ larger variability could account for this and represents the most important finding.