Low Hypnotizables Research Articles

Subjects’ hypnotizability level affects somatosensory evoked potentials to non-painful and painful stimuli

ObjectiveWe evaluated the working hypothesis that the EEG activity associated to non-painful and painful stimuli in condition of waking state (no hypnotic procedure) was related to the hypnotizability level. MethodsHypnotizability level was measured in 16 healthy subjects through the Italian version of the Stanford Hypnotic Susceptibility Scale (SHSS, score: 0–12). EEG data (56 electrodes) were recorded during non-painful and painful electrical stimuli applied to the left index finger. Cortical activity (vertex N1–P2 complex) was compared in subjects with low hypnotizability level (N=8, SHSS:0–6) vs. subjects with high hypnotizability level (N=8, SHSS:7–12). ResultsThe amplitude of the N1–P2 complex was lower in the High-hypnotizability compared to the Low-hypnotizability group over primary sensorimotor cortex (C3 and C4 electrodes) and centro-parietal midline areas (Cz and Pz electrodes) for non-painful and painful stimuli. The SHSS showed a statistically significant negative correlation with the vertex N1–P2 complex at C3 and Cz (r=−0.5, p<0.05) electrodes for non-painful stimuli. ConclusionCompared to the Low-hypnotizability subjects, High-hypnotizability subjects showed a reduced cortical activity related to non-painful and painful stimuli. SignificanceThe results suggest a relationship between hypnotizability and cortical activity related to non-painful and painful stimuli in the condition of waking state (no hypnotic effect).

Hypnotizability and haptics: visual recognition of unimanually explored ‘nonmeaningful’ objects

The cognitive trait of hypnotizability modulates sensorimotor integration and mental imagery. In particular, earlier results show that visual recognition of 'nonmeaningful', unfamiliar objects bimanually explored is faster and more accurate in subjects with high (Highs) than with low hypnotizability (Lows). The present study was aimed at investigating whether Highs exhibit a similar advantage after unimanual exploration. Recognition frequency (RF) and Recognition time (RT) of correct recognitions of the explored objects were recorded. The results showed the absence of any hypnotizability-related difference in recognition frequencies. In addition, RF of the right and left hand was comparable in Highs as in Lows, while slight differences were found in RT. We suggest that hemispheric co-operation played a key role in the better performance of Highs in the bimanual task previously studied. In the unimanual exploration, the task's characteristics (favoring the left hand), hypnotizability-related cerebral asymmetry (favoring the right hand in Highs) and the possible preferential verbal style of recognition in Lows (favoring the right hand in this group) antagonize each other and prevent the occurrence of major differences between the performance of Highs and Lows.

Individual differences and state effects on mind-wandering: Hypnotizability, dissociation, and sensory homogenization

Consciousness alterations can be experienced during unstructured, monotonous stimuli. These effects have not been linked to particular cognitive operations; individual differences in response to such stimulation remain poorly understood. We examined the role of hypnotizability and dissociative tendencies in mind-wandering (MW) during a sensory homogenization procedure (ganzfeld). We expected that the influence of ganzfeld on MW would be more pronounced among highly hypnotizable individuals (highs), particularly those high in dissociative tendencies. High and low hypnotizables, also stratified by dissociation, completed the sustained attention to response task during ganzfeld and control conditions. High dissociative highs made more commission errors during ganzfeld, suggesting increased MW, whereas the other groups displayed the opposite pattern. Increases in commission errors from the control condition to ganzfeld were associated with more alterations in consciousness and negative affect, but only among highs. Sensory homogenization had opposite effects on MW depending on the interaction of hypnotizability and dissociation.

The neurophenomenology of neutral hypnosis

IntroductionAfter a hypnotic induction, medium and highly hypnotizable individuals often report spontaneous alterations in various dimensions of consciousness. Few studies investigating these experiences have controlled for the inherent demands of specific hypnotic suggestions and fewer still have considered their dynamic properties and neural correlates. MethodsWe adopted a neurophenomenological approach to investigate neutral hypnosis, which involves no specific suggestion other than to go into hypnosis, with 37 individuals of high, medium, and low hypnotizability (Highs, Mediums, and Lows). Their reports of depth and spontaneous experience at baseline, following a hypnotic induction, and then after multiple rest periods were analyzed and related to EEG frequency band power and global functional connectivity. ResultsHypnotizability was marginally associated with lower global functional connectivity during hypnosis. Perceived hypnotic depth increased substantially after the induction especially among Highs and then Mediums, but remained almost unchanged among Lows. In the sample as a whole, depth correlated moderately to strongly with power and/or power heterogeneity for the fast EEG frequencies of beta2, beta3, and gamma, but independently only among Highs. The spontaneous phenomenology of Lows referred primarily to the ongoing experiment and everyday concerns, those of Mediums to vestibular and other bodily experiences, and those of Highs to imagery and positive affect/exceptional experiences. The latter two phenomena were associated with lower global functional connectivity during hypnosis. Imagery correlated positively with gamma power heterogeneity and negatively with alpha1 power heterogeneity. Generally, the pattern of correlations for the Highs was the opposite of that for the Lows. ConclusionsExperienced hypnotic depth and spontaneous phenomena following a neutral hypnotic induction vary as a function of hypnotizability and are related to global functional connectivity and EEG band wave activity.

EEG phase synchronization during hypnosis induction

Hypnosis is a mental state or set of attitudes usually induced by a procedure known as hypnotic induction. In order to provide the basic physiological conditions for potentially successful hypnosis treatment of medical and psychological problems, the determination of a subject’s hypnotizability level is important. Currently, the hypnotizability level is determined using different standard subjective tests. To avoid the different drawbacks of these subjective clinical tests, a practical objective method based on the correlation between electroencephalograph (EEG) phase synchronization and hypnosis susceptibility levels is presented in this study. This method can be used by clinicians instead of the traditional subjective methods to classify hypnotizability level. Thirty-two subjects with different hypnosis susceptibility levels contributed to this research. Using statistical analyses, it was concluded that, in highly hypnotizable people, the EEG phase synchronization between different paired channels, located on the frontal lobe, is significantly different from that in subjects with medium or low hypnotizability.

EEG sLORETA Functional Imaging During Hypnotic Arm Levitation and Voluntary Arm Lifting

This study (N = 37 with high, medium, and low hypnotizables) evaluated depth reports and EEG activity during both voluntary and hypnotically induced left-arm lifting with sLORETA functional neuroimaging. The hypnotic condition was associated with higher activity in fast EEG frequencies in anterior regions and slow EEG frequencies in central-parietal regions, all left-sided. The voluntary condition was associated with fast frequency activity in right-hemisphere central-parietal regions and slow frequency activity in left anterior regions. Hypnotizability did not have a significant effect on EEG activity, but hypnotic depth correlated with left hemisphere increased anterior slow EEG and decreased central fast EEG activity. Hypnosis had a minimal effect on depth reports among lows, a moderate one among mediums, and a large one among highs. Because only left-arm data were available, the full role of the hemispheres remains to be clarified.

Are High Hypnotizables Especially Vulnerable to False Memory Effects? A Sociocognitive Perspective

This article examines issues raised by a recent UK legal case in which the defense argued that the accusations made by the highly hypnotizable plaintiff were likely based on false memories. The authors argue that the evidence related to hypnotizability and false memory production is inconsistent but may be illuminated by a sociocognitive perspective. They present 2 preliminary studies that indicate that when the instructions imply that accurate reporting is a feature of hypnosis, higher hypnotizables may actually be more resistant than low or medium hypnotizables to false memories arising from misleading information given during hypnosis. They conclude that, when memory accuracy is emphasized rather than productivity, there is little evidence to link high hypnotizability with a propensity to produce false memories.

Neurophysiological Correlates of Post-Hypnotic Alexia: A Controlled Study with Stroop Test

To clarify whether hypnotically-induced alexia was able to reduce the Stroop effect due to color/word interference, 12 volunteers (6 with high and 6 with low hypnotizability according to Stanford Hypnotic Susceptibility Scale Form C) underwent a Stroop test consisting of measuring, both in basal conditions and during post-hypnotic alexia, the reaction times (RT) at appearance of a colored word indicating a color. In basal conditions, RT were greater in case of incongruence. In highly hypnotizable participants, the interference was less pronounced during post-hypnotic alexia (−34%, p = 0.03). During alexia, late positive complexamplitude was also greater for congruent than incongruent conditions (p < 0.03), and cardiovascular response to stress was less pronounced as well. In participants showing low hypnotizability, no reduction of Stroop effect was detected during post-hypnotic alexia. Post-hypnotic alexia is therefore a real and measurable phenomenon, capable of reducing the color-word interference and the haemodynamic effects of the Stroop test.

EEG Correlates of Virtual Reality Hypnosis

The study investigated hypnosis-related electroencephalographic (EEG) coherence and power spectra changes in high and low hypnotizables (Stanford Hypnotic Clinical Scale) induced by a virtual reality hypnosis (VRH) induction system. In this study, the EEG from 17 participants (Mean age = 21.35, SD = 1.58) were compared based on their hypnotizability score. The EEG recording associated with a 2-minute, eyes-closed baseline state was compared to the EEG during a hypnosis-related state. This novel induction system was able to produce EEG findings consistent with previous hypnosis literature. Interactions of significance were found with EEG beta coherence. The high susceptibility group (n = 7) showed decreased coherence, while the low susceptibility group (n = 10) demonstrated an increase in coherence between medial frontal and lateral left prefrontal sites. Methodological and efficacy issues are discussed.

Effects of Vestibular and Neck Proprioceptive Stimulation on Posture as a Function of Hypnotizability

Previous studies on the role of hypnotizability in postural control indicate that the body sway of subjects with high or low hypnotizability to hypnosis is differentially modulated by eye closure. The aim of this study was to investigate whether hypnotizability also modulates the postural response to electrical vestibular stimulation and to head rotation in nonhypnotized individuals. The center of pressure (CoP) displacements were monitored in highs and lows standing on a stabilometric platform with closed eyes during basal conditions and electrical vestibular stimulation in 3 different positions of the head. Results showed that the CoP stimulus-locked displacements as well as the CoP mean position, area, and mean velocity were similar in highs and lows, but only in lows did the head position modulate the mean velocity. This finding might reflect a difference in sensory-motor integration between the 2 groups.

Focused analgesia in waking and hypnosis: Effects on pain, memory, and somatosensory event-related potentials

Somatosensory event-related potentials (SERPs) to painful electric standard stimuli under an odd-ball paradigm were analyzed in 12 high hypnotizable (HH), 12 medium hypnotizable (MH), and 12 low hypnotizable (LH) subjects during waking, hypnosis, and a cued eyes-open posthypnotic condition. In each of these conditions subjects were suggested to produce an obstructive imagery of stimulus perception as a treatment for pain reduction. A No-Analgesia treatment served as a control in waking and hypnosis conditions. The subjects were required to count the number of delivered target stimuli. HH subjects experienced significant pain and distress reductions during posthypnotic analgesia as compared to hypnotic analgesia and between these two analgesic conditions as compared to the two control conditions. Outside of hypnosis, these subjects remembered less pain and distress levels than they reported during hypnotic and posthypnotic analgesia treatments. In contrast, for waking-analgesia treatment, HH subjects remembered similar pain and distress levels to those they reported concurrently with the stimulation. HH subjects, during hypnotic and posthypnotic analgesia treatments, detected a smaller number of target stimuli and displayed a significant amplitude reduction of the midline frontal and central N140 and P200 SERP components. No significant SERP differences were observed for these subjects between treatments in waking condition and between hypnotic and posthypnotic analgesic treatments. For the MH and LH subjects no significant N140 and P200 amplitude changes were observed among analgesic conditions as compared to control conditions. These amplitude findings are seen as indicating that hypnotic analgesia can affect earlier and later stages of stimulus processing.

Commentary: Remembrance of Hypnosis Past

This is an elaborate critique that uses many old concepts regarding hypnosis as a basis for its premises. It would help move the field forward, and out of the past, if the authors would take into account the newer neurophysiological data which helps to explain the wide range of amplitude and differences in responsivity to suggestion which are associated with high, low & mid-range hypnotizability. The authors make much from older work which defines hypnotic phenomena as a susceptibility rather than the newer findings which identify the degree to which an individual can experience the hypnotic state as an innate ability or talent (H. Spiegel & Greenleaf, 2006). Using the old paradigm leads to a confirmation of an old thesis. The large variety of induction ceremonies (including some which are absurd, yet functional) is clear evidence that it sometimes is less about what we do, than it is evidence that trance capacity is an inherent talent (not susceptibility) that can be activated in many ways. The degree of trance experience varies with each individual. The basic level of response reflects a neuro-circuitry (probably genetic) which can be secondarily enhanced somewhat with guidance and motivation. This is reflected in experiments which demonstrate significantly different measurable physiological responses to suggestion from high to mid-range to low when the measure of hypnotizability includes the bio-psycho-social attributes of the individual and the measure of hypnotizability is not limited to behavioral responses (Greenleaf, Fisher, Miaskowski & DuHamel, 1992; Horton, Crawford, Harrington & Downs, 2004; Kosslyn & Spiegel, 2000; Raz, A., 2005; D. Spiegel, 1989; H. Spiegel & D. Spiegel, 2004). The induction ceremony simply activates the inherent capacity of the cooperating person, inferring the message – pay attention and shift gears. Or, more frequently, it is activated spontaneously when the person automatically or consciously decides to increase concentration (H. Spiegel & Greenleaf, 2005-2006). Suggestion and/or self-initiation of trance produce a reduction of peripheral awareness with a corresponding increase in focal attention and dissociation. Since

Focused hypnotic analgesia: Local and remote effects

Suggestion for hypnotic analgesia aimed at a specific body area is termed “focused hypnotic analgesia”. It is not clear, however, whether this analgesia is limited to a specific body location or spread all over the body. Focused hypnotic analgesia was studied, in response to ascending electrical stimuli, when analgesia and stimulation were applied to the same area (local), and when analgesia was applied to one location and stimulation was delivered to a different area (remote). The face or leg served alternately as the local or remote areas, and the effect was tested in 12 high-hypnotizable (HH) and 13 low-hypnotizable (LH) subjects. Hypnotic analgesia in the local site produced a significant pain reduction compared to the remote site in HH subjects ( P < 0.0001) but not in LH subjects ( P = 0.68). As stimuli increased in intensity the reduction in pain as a result of hypnosis was larger both in HH and LH subjects ( P < 0.0001). Nevertheless, significant analgesia occurred in the 3 highest intensities in the local and remote location of HH subjects, but only in 2 highest intensities in the local and 1 in the remote of LH subjects. We conclude that in HH subjects focused hypnotic analgesia is mostly confined to the area aimed at, but some spread of analgesia to remote areas cannot be dismissed all together. Alternatively, this “spread” of analgesia could be due to a placebo effect in the remote area. Focused hypnotic analgesia requires increased attention to the body area aimed at, unlike analgesia achieved by distraction of attention.

Pain Reduction is Related to Hypnotizability but Not to Relaxation or to Reduction in Suffering: A Preliminary Investigation

The present study examined the facilitation of pain reduction through the use of a pain reduction protocol. The protocol emphasized converting pain sensations into visual and auditory representations, which then were manipulated through therapeutic suggestion. Hypnosis was not mentioned in the intervention, minimizing creation of expectancy effects related to hypnosis. At the conclusion of the study, the Stanford Clinical Hypnotic Scale was administered. Measures of relaxation and reduction of suffering were not related to hypnotizability. However, pain reduction was significantly related to hypnotizability (r =.55, P <. 001). High hypnotizables had a greater reduction in pain than low hypnotizables, even though both had equivalent degrees of relaxation.

An Integrative, Multi-Factor Conceptualization of Hypnosis

(2005). An Integrative, Multi-Factor Conceptualization of Hypnosis. American Journal of Clinical Hypnosis: Vol. 48, No. 2-3, pp. 131-135.

Focused analgesia and generalized relaxation produce differential hypnotic analgesia in response to ascending stimulus intensity

This study was designed in order to examine the effects of different types of hypnotic suggestion on hypnotic analgesia. Generalized relaxation and focused analgesia were induced in seven high-hypnotizable (HH) and eight low-hypnotizable (LH) subjects. Subjects were not aware to which group they belonged. The two groups did not differ in their expectation rates to achieve analgesia under hypnosis. Pain intensity and unpleasantness were rated on visual analogue scales in response to painful electrical stimuli, delivered in random order in five ascending intensities. Both focused analgesia and generalized relaxation decreased pain intensity significantly ( P<0.01). However, stimulus-intensity response curves differed under the two hypnotic conditions. As stimulus intensity became higher pain reduction was enhanced under focused analgesia, while a constant reduction occurred under generalized relaxation. The interaction between hypnotic state and stimulus intensity was significant for focused analgesia ( P<0.05) but not for generalized relaxation ( P>0.07), difference became more pronounced when analyzed for HH subjects only ( P<0.002 for analgesia, P>0.10 for relaxation). Pain reduction was significantly higher in HH than in LH subjects under focused analgesia ( P<0.02) but not under generalized relaxation ( P>0.5). We conclude that by utilizing two modes of hypnotic suggestions in response to ascending stimuli, we were able to discover two components of hypnotic analgesia. One shows a parallel shift in the stimulus–response function, has features similar to placebo and bears no clear relationship to hypnotic susceptibility. The other shows a slope change in the stimulus–response curve and has a positive relationship to hypnotic susceptibility.

The involvement of frontally modulated attention in hypnosis and hypnotic susceptibility: cortical evoked potential evidence

AbstractThe frontal N100 difference wave (N100d) between cortical evoked potentials to frequent and infrequent tones was compared before and during hypnosis in subjects with high and low hypnotic susceptibility (n = 10,11). This was to test putative alterations in attention, novelty detection in particular, modulated by anterior functions including the anterior cingulate to auditory stimuli extraneous to hypnosis. Susceptibility was measured with the HGSHS:A and validated with a laboratory scale during the experiment. Results showed that in the highly susceptible participants the N100d was clearly manifested in the pre‐hypnosis control condition, was later attenuated following instructions of hypnosis and was virtually absent after further hypnosis. The effect was due to attenuated responding to the infrequent stimulus, without change to the frequent stimulus. This compromise extended to the later frontal P300 wave whose amplitude was reduced by 50% with hypnosis and was negligible by the end of hypnosis. The parietal P300 was reduced in both hypnosis conditions to a similar degree. These results were consistent with a progressive reduction throughout the hypnotic induction in focused attention to stimuli incidental to hypnosis capable of frontal modulation and frontal activation to the novel stimulus. In contrast the participants with low susceptibility showed an opposite pattern of change in the N100d. Though absent before hypnosis there was a progressive increase in the N100d from the first to the second hypnosis recording. This was underpinned by changes in response amplitudes to both frequent and infrequent stimuli, without systematic changes to the P300. Their results supported a dispersion of attentional resources and an absence of frontal activation in the pre‐hypnosis baseline, compatible with a lack of focused attention and engagement of frontal functions theorized to be necessary for hypnosis. Furthermore subjects with low hypnotizability showed a longer P300 latency at the central parietal peak compatible with more prolonged processing of the rare stimulus, in keeping with a more posterior bias in processing. This may militate against the induction of hypnosis, theorized to require initial engagement of anterior processes, and here supported by the results in the highly hypnotizable participants. Copyright © 2002 British Society of Experimental and Clinical Hypnosis

Autonomic reactivity to cognitive and emotional stress of low, medium, and high hypnotizable healthy subjects: Testing predictions from the high risk model of threat perception

This study tested hypotheses derived from Wickramasekera's High Risk Model of Threat Perception (HRMTP) by comparing autonomic and affective responses to a cognitive and an emotional stress task in high, medium, and low hypnotizables. Electrodermal activity (EDA) was used as a measure of sympathetic activity, and the high frequency (HF) spectral component of heart rate variability as a measure of parasympathetic activity. High hypnotizables exhibited greater EDA at baseline and slower EDA recovery following both tasks than did medium and lows. Medium hypnotizables responded with greater decreases in normalized HF power than did highs and lows during the emotional stress task. The results suggest diminished EDA variability in high hypnotizables and the potential for HF power as an indicator of autonomic dysregulation in low and high hypnotizables, compared to mediums. The results are discussed in relation to predictions based on the HRMTP.

EEG Source Localization and Global Dimensional Complexity in High- and Low- Hypnotizable Subjects: A Pilot Study

Individuals differ in hypnotizability. Information on hypnotizability-related EEG characteristics is controversial and incomplete, particularly on intracerebral source localization and EEG dimensionality. 19-channel, eyes-closed resting EEGs from right-handed, healthy, 8 high- and 4 low-hynotizable subjects (age: 26.7 ± 7.3 years) were analyzed. Hypnotizability was rated after the subjects’ ability to attain a deep hypnotic stage (amnesia). FFT Dipole Approximation analysis in seven EEG frequency bands showed significant differences (p < 0.04) of source gravity center locations for theta (6.5–8 Hz, more posterior and more left for highs), beta-1 and beta-2 frequencies (12.5–18 and 18.5–21 Hz; both more posterior and more right for highs). Low Resolution Electromagnetic Tomography (LORETA) specified the cortical anteriorization of beta-1 and beta-2 in low hypnotizables. Power spectral analysis of Global Field Power time series (curves) showed no overall power differences in any band. Full-band Global Dimensional Complexity was higher in high-hypnotizable subjects (p < 0.02). Thus, before hypnosis, high and low hypnotizables were in different brain electric states, with more posterior brain activity gravity centers (excitatory right, routine or relaxation left) and higher dimensional complexity (higher arousal) in high than low hypnotizables.

Anterior brain functions and hypnosis: A test of the frontal hypothesis

Neuropsychological frontal lobe tests were used to compare individuals with high (n = 8) and low (n = 9) hypnotizability during both baseline and hypnosis conditions. Subjects were assessed on two hypnotic susceptibility scales and a test battery that included the Stroop test, word fluency to letter- and semantic-designated categories, tests of simple reaction time and choice reaction time, a vigilance task, and a questionnaire of 40 self-descriptive statements of focused attention. Effects for hypnotic susceptibility and hypnosis/control conditions were scant across the dependent variables. High hypnotizables scored higher on the questionnaire at baseline, and their performance on the word-fluency task during hypnosis was reduced to a greater extent than lows. Findings indicate that although the frontal area may play an important role regarding hypnotic response, the mechanisms seem to be much more complex than mere general inhibition.