Does the more vivid imagery of high hypnotizables depend on greater cognitive effort? A test of dissociation and social-cognitive theories of hypnosis

Three Simulated Goalball Games in the Same Day Cause Central Fatigue and Can Impair Game Technical Performance

The purpose of this study was to investigate the effects of three simulated goalball games on neuromuscular, physiological, perceptual, and technical parameters. Ten male players underwent assessments before and immediately after each game. Heart rate was recorded at rest and during all games that were entirely filmed for further technical performance analysis. Exercise significantly decreased knee extensor muscles peak force and percentage of voluntary activation after the second and third games, indicating the presence of central fatigue. Heart rate responses remained predominantly in a range equivalent to moderate activity intensity in all games. In addition, perceptual parameters were associated with reduced frequency of throws and density of actions. These findings suggest significant implications for the management of physical training, game strategy during a competition, and fixture change from three to two games per day.

The varied relationship between hypnosis and dissociative phenomena: Implications for traumatology

Although metanalytic evidence exists to support the long-term efficacy of hypnotic interventions in the treatment of trauma, assertions that hypnosis may induce trauma or exacerbate existing posttraumatic reactions through activating dissociative processes seem to persist in some circles. While multiple studies have established that hypnotic induction produces dissociative phenomena, what has not yet been clearly explicated is the degree to which varieties of dissociative phenomena differentially elicited by hypnotic induction tend to skew toward the pathological or nonpathological end of the continuum of dissociation. The authors of the current study explore the connection between hypnotic susceptibility and facets of dissociation, employing the Harvard Group Scale of Hypnotic Susceptibility: A (HGSHS:A) and the State Scale of Dissociation (SSD). A significantly greater change in state dissociation was observed in their hypnosis condition as compared with a novel control condition (t (82) = 3.235, p =.002, d =.70), confirming that a relationship appears to exist between hypnosis and dissociation. A discussion of the differential effect of hypnosis on SSD subscales follows, specifically indicating less activation of the more putatively pathological facets, namely identity confusion and identity alteration. This finding may serve to assuage some concerns around the potential for iatrogenesis in working with traumatized patients.

Brain Activity and Functional Connectivity Associated with Hypnosis

Hypnosis has proven clinical utility, yet changes in brain activity underlying the hypnotic state have not yet been fully identified. Previous research suggests that hypnosis is associated with decreased default mode network (DMN) activity and that high hypnotizability is associated with greater functional connectivity between the executive control network (ECN) and the salience network (SN). We used functional magnetic resonance imaging to investigate activity and functional connectivity among these three networks in hypnosis. We selected 57 of 545 healthy subjects with very high or low hypnotizability using two hypnotizability scales. All subjects underwent four conditions in the scanner: rest, memory retrieval, and two different hypnosis experiences guided by standard pre-recorded instructions in counterbalanced order. Seeds for the ECN, SN, and DMN were left and right dorsolateral prefrontal cortex, dorsal anterior cingulate cortex (dACC), and posterior cingulate cortex (PCC), respectively. During hypnosis there was reduced activity in the dACC, increased functional connectivity between the dorsolateral prefrontal cortex (DLPFC;ECN) and the insula in the SN, and reduced connectivity between the ECN (DLPFC) and the DMN (PCC). These changes in neural activity underlie the focused attention, enhanced somatic and emotional control, and lack of self-consciousness that characterizes hypnosis.

Synaesthesia-type associations and perceptual changes induced by hypnotic suggestion

Are synaesthetic experiences congenital and so hard-wired, or can a functional analogue be created? We induced an equivalent of form-colour synaesthesia using hypnotic suggestions in which symbols in an array (circles, crosses, squares) were suggested always to have a certain colour. In a Stroop type-naming task, three of the four highly hypnotizable participants showed a strong synaesthesia-type association between symbol and colour. This was verified both by their subjective reports and objective eye-movement behaviour. Two resembled a projector- and one an associator-type synaesthete. Participant interviews revealed that subjective experiences differed somewhat from typical (congenital) synaesthesia. Control participants who mimicked the task using cognitive strategies showed a very different response pattern. Overall, the results show that the targeted, preconsciously triggered associations and perceptual changes seen in association with congenital synaesthesia can rapidly be induced by hypnosis. They suggest that each participant’s subjective experience of the task should be carefully evaluated, especially when studying hypnotic hallucinations. Studying such experiences can increase understanding of perception, automaticity, and awareness and open unique opportunities in cognitive neuroscience and consciousness research.

Seeing Blue As Red: A Hypnotic Suggestion Can Alter Visual Awareness of Colors

Some highly hypnotizable individuals have reported changes in objects' color with suggestions given in normal waking state. However, it is not clear whether this occurs only in their imagination. The authors show that, although subjects could imagine colors, a posthypnotic suggestion was necessary for seeing altered colors, even for a hypnotic virtuoso. She reported posthypnotic color alterations also selectively in response to specific target shapes in briefly presented object arrays. Surprisingly, another highly hypnotizable person showed a very different pattern of results. The control participants could not simulate virtuosos' results by applying cognitive strategies. The results imply that hypnosis can alter the functioning of automatic visual processes but only in some of the most hypnotizable individuals.

Musical agency reduces perceived exertion during strenuous physical performance

Music is known to be capable of reducing perceived exertion during strenuous physical activity. The current interpretation of this modulating effect of music is that music may be perceived as a diversion from unpleasant proprioceptive sensations that go along with exhaustion. Here we investigated the effects of music on perceived exertion during a physically strenuous task, varying musical agency, a task that relies on the experience of body proprioception, rather than simply diverting from it. For this we measured psychologically indicated exertion during physical workout with and without musical agency while simultaneously acquiring metabolic values with spirometry. Results showed that musical agency significantly decreased perceived exertion during workout, indicating that musical agency may actually facilitate physically strenuous activities. This indicates that the positive effect of music on perceived exertion cannot always be explained by an effect of diversion from proprioceptive feedback. Furthermore, this finding suggests that the down-modulating effect of musical agency on perceived exertion may be a previously unacknowledged driving force for the development of music in humans: making music makes strenuous physical activities less exhausting.

Posthypnotic suggestion alters conscious color perception in an automatic manner

The authors studied whether a posthypnotic suggestion to see a brief, masked target as gray can change the color experience of a hypnotic virtuoso. The visibility of the target was manipulated by varying the delay between the target and the mask that followed it. The virtuoso's subjective reports indicated that her conscious color experience was altered already at short delays between the target and the subsequent mask. The virtuoso's objectively measured pattern of responding under posthypnotic suggestion could not be mimicked either by control participants nor the virtuoso herself. Due to posthypnotic amnesia, the virtuoso was unaware of suggestions given during hypnosis. Importantly, the virtuoso could not alter her color perception without a hypnotic suggestion. These results suggest that hypnosis can affect even a highly automatic process such as color perception.

The effects of hypnosis on heart rate variability

Uslu et al. (2012 ) suggested that hypnotic status can modulate cerebral blood flow. The authors investigated the effects of hypnosis on heart rate variability (HRV). In women, HRV decreased during hypnosis. Posthypnotic values were higher compared to prehypnotic and hypnotic values. Women had highest HRV parameters in the posthypnotic condition. It appears that hypnosis can produce cardiac and cognitive activations. Hypnotherapy may be useful in some cardiac clinical conditions characterized by an autonomic imbalance or some cardiac arrhythmias.

Salient findings: hypnotizability as core construct and the clinical utility of hypnosis

Six papers of special interest to the hypnosis community have recently appeared in the general scientific literatures. Three of these papers were published as part of the 2006 Cochrane Collaboration on the utility of medical interventions. These reviews analyze the research literature on the efficacy of hypnosis for treatment of needle-related pain in children, pain management during childbirth, and conversion disorder. Hypnosis is the most promising psychological intervention studied for needle-related procedural pain and distress in children and adolescents; it is effective as an adjunctive analgesic during childbirth; and it is of uncertain usefulness in treatment of conversion disorder. A second cluster of three studies unambiguously demonstrates the central role of hypnotizability as a predictor of responsiveness in laboratory, analogue treatment, and medical practice settings. One of these articles may well be the most important hypnosis paper in many years.