They recorded 40-Hz EEG temporal density (35-45 Hz band) from the left and right temporo-parietal-occipital scalp regions in four emotional conditions (gladness, happiness, fear, and anger). When measures were made in the waking state, for Highs, during positive emotions they found increase in left and right hemisphere activity compared with resting condition. During fear and anger there was reduction in the left hemisphere and an increase in the right, but for some subjects no left hemisphere change.
Low hypnotizables did not show large or reliable differences across emotions. With the hypnotic state, they found the trend was even greater for Highs.

Pribram, Karl H. (1995). Brain in perception: From Kohler’s fields to Gabor’s quanta of information. In Proceeding of the 39th Congress of German Society for Psychology (pp. 53-69).

[The following material was taken from a paper provided by the author as a replacement for a presentation he made on the same topic at the Annual Meeting of the American Psychological Association, 1994, Los Angeles.]
Pribram presents the view that neuroelectric field theory (similar to theories proposed by Kohler and by Lashley earlier in this century) account for complexities observed in the relationship between awareness/perception and sensation. “Nerve impulse generation and transmission in neuronal circuits is but one of the important electrical characteristics of neural tissue. Another characteristic is the production of patterns of pre- and post-synaptic polarizations in axonal and dendritic arborizations. … [which] are produced everywhere in the brain cortex when nerve impulses arrive at synapses as a result of the fact that the impulses become attenuated due to decreased fiber size resulting from the branching of axons” (p. 53). The polarizations develop a wave front.
Georg von Bekesy performed experiments on tactile perception that demonstrated the complex relationship between sensation and awareness. We often ‘perceive’ an object as external to us, even though the immediate specific neural stimulation is of receptors and from there activity is transmitted to the neurons of the brain. Thus we ‘see’ an object as external to us, even though the light reflected from that object produces an image on our retina. The same kind of externalized projection occurs for hearing. Touch is ordinarily perceived as at the same location as the stimulation (i.e. in the body), except that the von Bekesy experiments demonstrated that touch could also be perceived at a distance, that is, outside the body, if conditions were appropriate.
In the von Bekesy experiments, a pair of vibrators were used to stimulate two fingers, with each vibrator actuated by the same series of clicks and with the delay of time between the clicks varied. “The interesting point in this experiment is that for the condition in which there is no time delay the vibrations are localized between the two fingers where no skin is present” (p. 55). When two vibrators are placed on the thighs, the experimental subject can, by moving the knees apart, experience the vibratory sensation localized in the open space between the knees! Such an externalization of tactile perception is observed in everyday life, as when in using a knife we seem to sense the edge of the knife in order to make the appropriate movements.
Following from von Bekesy’s work, it seems that only some neural processes lead to awareness. “In fact, instrumental (often automatized) behavior and awareness are to a large extent opposed; the more efficient a performance, the less aware we become. … for the neuroscientist, the question becomes: What kinds of neural activity allow awareness to be inversely related to automatized action?
“Patterns of synaptodendritic polarizations and nerve impulses are two kinds of processes that function reciprocally. A simple hypothesis states that the more or less persistent designs of dendritic field polarization patterns are coordinate with awareness (Pribram, 1971, Chapter 6). This view carries the corollary that circuits of nerve impulses per se and the behavior they generate are unavailable to immediate awareness. Even the production of speech is ‘unconscious’ at the moment the words are spoken” (pp. 55-56).
Some additional information comes from the experimental work of Ben Libet (1966, 1994), in which direct stimulation of brain tissue in waking subjects yields reports of awareness (of a particular part of the body tingling or being in a certain position). However, the awareness occurs 0.5 to 5 seconds post-stimulus, indicating that “electrical stimulation must set up some state in the brain tissue, and only when that state has been attained does the patient become aware” (p. 56).
The evidence of electrical fields comes from using both high pass filters and low pass filters on the electrical activity generated by the brain and picked up on EEG. There are ‘bursts’ of spikes, and onset of the field effect precedes the initiation of spikes. “Just as depolarization of axon membranes is a necessary precursor of the generation of action potentials, so also is the local build up of synaptodendritic field potentials a precursor to the recruitment of action potentials in post synaptic neurons” (p. 57).
Maps of the receptive field of an axon can be developed (e.g. using Kuffler’s procedure). However, stimulation outside of that receptive field can change that axon’s response–a field effect “produced in a more extended field of potentials occurring in neighboring synaptodendritic fields” (p. 58). In this investigation, the relationship between local field potentials of the rat somatosensory system (whisker stimulation) is studied using the Kuffler procedure. Whiskers were stimulated by rotating cylinders which varied in spacing of grooves and speed of rotation. The resulting variation in density of stimulation yielded a map or manifold of cortical bursts/spikes. Pribram’s research fits the experimentally generated data to a theoretical model derived from signal processing theory, using “a rectangular window in the spatiotemporal domain to constrain the two dimensional sinusoidal signal” (p. 62). They noted that the manifolds obtained from somatosensory cortex recordings were similar to receptive field characteristics measured at the primary visual cortex, which “suggests that this process is ubiquitous in the cortical synaptodendritic network” (p. 63).
Referring to the Fourier theorem (that “the original pattern can be reconstituted, reconstructed, by performing the inverse transform” p. 65), the author notes that experimental data are more complex than would be predicted. The author suggests that it would be helpful to employ the Gabor uncertainty principal, in which Gabor (1946) described as a fundamental unit a ‘quantum’ of information. “Gabor became interested in describing a joint spacetime-spectral domain because he noted that there is a limit on the precision to which simultaneous measurement of spectral components and [space]time can be made. … the Gabor relation describes the composition of a sensory channel, and the residual uncertainty defines the limits of channel processing span” (p. 65). The Gabor relationships are similar to those described in quantum physics by Heisenberg, so Gabor referred to a quantum of information, which he named a Logon.
The author describes his experimental results as exhibiting Gabor elementary functions, which “are composed in dendritic arborizations, receptive fields of the neurons from which we are recording. … Each logon, i.e. each such receptive field module, is a channel. According to Gabor, the ensemble of such channels is a measure of the degrees of freedom, the number of distinguishable dimensions or features (e.g., spatial and temporal frequency, degrees of orientations, preferred direction, color). The minimum uncertainty relation expressed by Gabor elementary functions sets the limits on the information processing competence of each of these channels” (pp. 65-66).
In a Coda to this chapter, the author notes that there is a discrepancy between fields (composed of arrival and departure patterns of synapto-dendritic polarizations) and perceptual awareness which “occurs within spacetime coordinates.” Discussion of the discrepancy my be found in Pribram and Carlton (1986). Holonomic brain theory in imaging and object perception. Acta Psychologica, 63, 175-210; and in Pribram (1991), Lecture 6 of Brain and Perception. Basically, there is top-down organization imposed by the cortical system on peripheral sensation/perception. “These various systems not only relate to one another in a hierarchical manner but that the higher order systems operate on lower order systems by interpenetrating. Thus, we ordinarily, immediately perceive named and categorized objects, not just sets of images (though we are capable of ‘imaging’ by suspending the higher order processes). There is abundant evidence of such top-down penetration in the visual, auditory and somatosensory neural systems” (p. 66).

Ray, William J. (1995, November). EEG signatures of hypnotic susceptibility and hypnosis: It’s what’s up front that matters. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Antonio, TX.

We have done three studies: a psychometric study, one in which we used traditional ways of looking at EEG, and more recent research.
Study I found that hypnotizability related to absorption, but not to tests of absent mindedness/cognitive failures, abuse/neglect, attachment, depression and anxiety, NEO Five Factor Test scales (Neuroticism, Extroversion, Openness to Experience, Agreeableness, and Conscientiousness) or the Marlow Crown Social Desirability Scale. Also there was no relationship to Bernstein and Putnam’s measure of dissociation, the DES. There is a hint of a relationship to the Openness Scale, actually.
Study II included a literature review on 3 questions: 1. Are there differential electrocortical differences between high and low susceptible individuals? 2. Are there electrocortical markers for the hypnotic state itself? 3. Are electrocortical differences found in the trance state mediated by hypnotic procedures?
Results of Study II are published in Graffin, Ray, & Lundy, 1995.
Study III investigated three questions: 1. Are there initial baseline psychophysiological differences between High and Low susceptible Ss? 2. Are there psychophysiological differences in baseline? 3. Are there behavioral differences on the challenge tasks during the Stanford-C?
The Pre-induction baseline followed by post-induction baseline are reported today. (They also administered tasks, not discussed here.)
Literature indicates that EEG theta is much higher for highs than lows, especially in frontal and temporal areas. This is a stable finding in a number of studies. There are also posterior differences, but they are not as significant. The differences in theta between highs and lows remains across different tasks (like imaging, spatial rotations, math). Whatever differences in theta exist when high and low hypnotizable subjects walk into the room, continue across tasks. The difference also is observable in alpha.
In the whole study we found no alpha differences and no hemisphere differences, but we did find theta differences.
We thought there would be less dimensionality as someone enters hypnosis. Dimensionality reflects EEG wave form (e.g. a sine wave is simple; more complex wave is multidimensional) and is analyzed with “chaos measures” [these notes may be poor regarding this issue]. But we didn’t find less dimensionality as people entered hypnosis. So if dimensionality reflects brain state maybe people don’t change state as they enter hypnosis.
Highs do show higher dimensionality vs lows, across all brain areas. What does this mean? It’s as if Highs walk into the experiment in a more imagery mode than lows, and they continue that way throughout the whole experiment.
The differences found in baseline were all in theta. We compared the Standard Induction vs Self Induction on the EEG Theta variable: highs show more theta across the whole brain than lows, and it doesn’t matter what type of induction is used.
De Pascalis gets me thinking about the role of attention in hypnosis. Following an induction, on 35-45 Hz band of EEG there is greater frontal activity for Lows whereas for Highs you see more activity posteriorly. The difference is on the rostral-caudal dimension rather than the lateral dimension.

Crawford, Helen J. (1994). Brain dynamics and hypnosis: Attentional and disattentional processes. International Journal of Clinical and Experimental Hypnosis, 42 (3), 204-232.

This article reviews recent research findings, expanding an evolving neuropsychophysiological model of hypnosis (Crawford, 1989; Crawford & Gruzelier, 1992), that support the view that highly hypnotizable persons (highs) possess stronger attentional filtering abilities than do low hypnotizable persons, and that these differences are reflected in underlying brain dynamics. Behavioral, cognitive, and neurophysiological evidence is reviewed that suggests that highs can both better focus and sustain their attention as well as better ignore irrelevant stimuli in the environment. It is proposed that hypnosis is a state of enhanced attention that activates an interplay between cortical and subcortical brain dynamics during hypnotic phenomena, such as hypnotic analgesia. A body of research is reviewed that suggests that both attentional and disattentional processes, among others, are important in the experiencing of hypnosis and hypnotic phenomena. Findings from studies of electrocortical activity, event-related potentials, and regional cerebral blood flow during waking and hypnosis are presented to suggest that these attentional differences are reflected in underlying neurophysiological differences in the far fronto-limbic attentional system.

Crawford, Helen J. (1994). Brain systems involved in attention and disattention (hypnotic analgesia) to pain. In Pribram, Karl H. (Ed.), Origins: Brain and self organization (pp. 661-679). Hillsdale, NJ: Lawrence Erlbaum Associates.

Data are reviewed from regional cerebral blood flow, EEG, and somatosensory event-related potential (SERP; both scalp and intracranial) studies of attention to and disattention (hypnotic analgesia) of painful stimuli to provide further evidence for two neurophysiological systems of pain involving the cortex: (1) the epicritic, sensory system of pain associated with the parietal, posterior region, and (2) the protocritic, distress, comfort-discomfort system of pain associated with the far fronto- limbic region. Studies of neurophysiological changes accompanying suggested hypnotic analgesia support the hypothesis that the executive controller of the far frontal cortex, via the far fronto-limbic attentional system, acts as a gate against the ascent of painful stimuli into conscious awareness by ‘directing’ downward the inhibition of incoming somatosensory information coming from the thalamic region. In hypnotically responsive individuals who could eliminate the perception of pain, reviewed studies demonstrated increased regional cerebral blood in the frontal and somatosensory regions, shifts in hemispheric dominance of EEG theta power, differential surface SERP topographical patterns in the anterior and posterior regions of the brain, and reduction of the intracranial SERP P160 waveform in the gyrus cingulus.

Paradoxically, there may be physiological reactivity to pain stimuli while the hypnotized Subject reports they are not consciously aware of pain. Posner’s proposal of two different attentional systems may account for why there is physiological reactivity concurrent with lack of awareness of pain. Posner suggested that the posterior brain is involved with engaging and disengaging attention while the anterior brain is involved in attention for action or effortful attention. “Thus, the posterior region is involved in space and time, the epicritic processes, whereas the anterior region is involved in comfort- discomfort, the protocritic processes (Pribram, 1991)” (p. 665).
In parallel, there appear to be two systems of pain involving the cortex, as revealed in positron emission tomography research. Also relevant is clinical data showing that “removal of the frontal or cingulate cortex in patients with intractable pain leads to the amelioration of distress while not eliminating sensory pain (Bouckoms, 1989)” (p. 665).
The author proposes a neuropsychophysiology of hypnotic analgesia based on Hilgard’s (1986) neodissociation theory of hypnosis, together with Pribram and McGuinness’ (1975, 1992) attention model. In this view, “Hilgard’s executive control system is the far frontal cortex ‘directing’ the inhibition of incoming painful stimuli” (p. 666) after determining that the somatosensory signal is ‘irrelevant.’
“Highly hypnotizable individuals (‘highs’) have greater attentional and disattentional abilities than low hypnotizable individuals (‘lows’). … Recent neuroimaging techniques (PET, SPECT, CBF) that assess regional brain metabolism have found no differences in waking conditions between low and highly hypnotizable individuals, but have consistently reported that only highs show increased cerebral blood flow during hypnosis, suggestive of enhanced cognitive effort (Crawford, Gur et al., 1993; Halama, 1989; Meyer, Diehl, Ulrich, & Meinig, 1989; Walter, 1992)” (p. 666).
The hippocampus appears to be involved as a gating mechanism in selective attention (Crowne, Konow, Drake & Pribram, 1972; Isaacson, 1982, Isaacson & Pribram, 1986; R. Miller, 1991; Pribram, 1991; Arnolds et al., 1980) This gating function may be promoted “through a cortico-hippocampal relay [that] transmits information by theta wave modulation and Hebbian synaptic modification so that there is selective disattention” (p. 667). The author suggests that hypnotic pain control may involve directing attention away from pain sensory signals.
Highly hypnotizable people generate more EEG theta than low hypnotizables whether they are hypnotized or not, and Crawford (1990) observed marked hemispheric shifts in theta when highs (but not lows) were attempting to control pain with hypnosis.
This paper reports on preliminary results of SERP studies of people given hypnotic analgesia suggestions to reduce electric shock stimulus evoked pain. The results were analyzed individual by individual, because group data obscured pronounced shifts in SERP patterns (e.g. habituation rates differed among Subjects). For highs, the SERP tended to be reduced, and the lower amplitudes were observed as early as the N100-P200 components. This did not occur for low hypnotizables.
Different kinds of mechanisms may be operative for high hypnotizables, however. “In over half of the high hypnotizable subjects the far frontal region (Fp1, Fp2) showed strong arousal during attention to pain, but during hypnotic analgesia there was a flattening out of the SERPs to the point they are hard to measure. By contrast, the more posterior SERPs (including F3 and F4), while reduced in amplitude, were still evident. The other half of highs showed little SERP activity in the far frontal region in either attend or disattend conditions, but substantial reductions of SERPs at all locations during hypnotic analgesia” (p. 670). Additionally, some of the highs evidenced a contingent negative variation (CNV) or a late 400-500 msec negativity in the far frontal region, which author is inclined to interpret as “a preparation for a response or for an inhibition of a response” (p. 670).
Case studies of two patients with intracranial electrodes and scalp electrodes recording SERPs are presented in support of the experimental data. The two female patients were diagnosed with obsessive compulsive disorder; one was highly hypnotizable and one was not. They received 30 moderately painful stimuli to the left middle finger under sequential conditions: waking attention, hypnosis with analgesia suggestions, and hypnosis with attention instructions. The highly hypnotizable patient reported significantly less pain during suggested analgesia, and that reduction in pain was associated temporally with reduction of SERP at P160 in the gyrus cingulus (and at no other recording sites). The ‘unhypnotizable’ patient showed no SERP changes. As an aside, the author notes that “Subsequent to the hypnotic analgesia, when the pain was attended to again during waking this patient showed a significant enhancement of the same positivity wave at Fz, as if there was a rebound effect (something we have also observed in some of our SERP subjects at the BRAINS Center)” (p. 674).

Freeman, R.; Barabasz, A.; Barabasz, M. (1994, October). EEG topographic differences between dissociation and distraction during cold pressor pain in high and low hypnotizables. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Francisco.

Hilgard once said we should study what is going on inside the skull when we study hypnotic behavior. Theta EEG was studied, in 3.5 and 5.5-7.5 band widths, based on Crawford’s research (no differences between high and low hypnotizables in low range but significant differences in waking state, eyes closed condition).
Also employed new type of distraction procedure. Previously used as comparison conditions things like imagine a pleasant scene, do whatever you can do to reduce pain, or imagine an instructor giving a lecture. Barabasz theorized that highs, given the opportunity, may spontaneously get involved in imagery; so distraction used in some experiments may actually become hypnosis. Here, distraction involved using a storage box, with plexiglass covering front, and 3 lights–subjects were to recall sequence of light changes that occurred during 60 sec when arm was in the cold water.
Cold pressor pain. 3 immersions with simultaneous pain reporting and EEG monitoring. –Waking State –Light array distraction –Hypnotic induction and suggested analgesia (Distraction and hypnosis with analgesia were presented in a balanced design)
Pain Ratings ranged from 0 = no pain, 10 = level would very much like to remove arm from water (rating could exceed 10 however). After removing arm, subjects were to report the maximum amount of pain that they had felt. Pain Scores were obtained at 30 seconds and 60 seconds after immersion in the cold water.
Also got qualitative data. During recovery period after each arm immersion, Subjects were asked what if anything they had done to reduce the pain felt.
30 second pain scores: Waking 7.60 vs 7.50 Distraction 8.60 vs 6.80 Hypnotic analgesia 7.80 vs 4.10 (Significantly different).
60 second pain scores: Showed same trend
There was no difference whatsoever for the lows.
Results for the 2 EEG sites: P3 left hemisphere parietal in waking and hypnotic analgesia, high theta, had significantly different activity O1 left hemisphere in waking and hypnotic analgesia, was significantly different between highs and lows (same as above).
Results for two theta ranges: Low theta range, T4 temporal right hemisphere, for lows in waking and [missed words] condition–hard to interpret this finding.
Highs demonstrated pain reduction in hypnotic analgesia compared to waking and distraction conditions and compared to lows. Lows had no differences in any condition.
Enhanced EEG theta in left parietal area differentiated highs and lows. This suggests that highs generate enhanced disattention that may be controlled by these areas.
P3 area regulates the integration and association of somatic perceptions. The O1 area controls processing of visual imagery. Perhaps high hypnotizables have more ability to alter afferent sensory information through focused attentional processes. Also, the ability to alter the suffering portion of pain experience may involve visual imagery activity.
State and trait differences are apparent.
The low theta range may be more closely related to slower delta range 0-3.5 that is associated with sleep and drowsiness. High theta = low arousal and attention capacity. That’s why theta seems associated with wide range of behaviors that appear contradictory
The qualitative data shows highs reported they spontaneously preferred strategies that were more than distraction (associating colors with warmth, thinking of warm water) and the most frequent responses of lows were “nothing” or “told myself it would be over soon.”
Highs in analgesia condition used no specific strategy: 8/10 reported the arm simply felt more numb.

Ray, William J.; Moraga, R.; Faith, M. (1994, October). Psychometric and psychophysiological studies of hypnotizability and dissociation. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Francisco.

In the last 5-6 years we see a beginning of a consistency in this type of research on EEG and hypnosis. Baseline EEG theta for high and low hypnotizable Ss was higher significantly in frontal and temporal areas; less significantly in parietal and occipital areas. It begins to look like a signature of hypnotizability. Our research will be published in the Journal of Abnormal Psychology next year.
In Japan they see theta as sustained attention; some aspects of theta relate to MAO and also to dopamine. Betsy Faith did the same research, replicating almost exactly.
There are no differences between Highs and Lows in alpha or beta; but we find differences in theta (especially frontal, and in 40 Hz more posteriorly). It may not be L-R hemisphere difference as previously thought, but more a rostral-caudal dimension.
The signature to hypnotizability is more frontal theta at baseline. This may also relate to a drop in theta after induction, but those results are not so clear. Highs have a larger drop in theta from pre to post induction than is observed in the Lows.
We did a “chaos analysis” of EEG. There are three main measures, including dimensionality. Dimensionality is a measure of complexity. People demonstrate high dimensionality when asked to do tasks, low dimensionality in anesthesia.
High hypnotizable Ss start an induction with higher dimensionality than the Low hypnotizable Ss, and as we go through the induction they remain the same. So this measure shows individual differences but does not give evidence of a state (because it doesn’t change).
Chaos dimensions for 2 mental math problems show lower dimensions in frontal compared to posterior areas; but for imagery [labeled on slide as positive and negative emotional tasks] the dimension is the same across areas.
For the dimension measures, lows look like they are doing mental math and highs look like they are doing imagery, in baseline.
SECOND PART OF RESEARCH–DISSOCIATION. For 100 years dissociation and hypnosis have been viewed as similar. Two dissociation scales were used – Putnam’s DES and Reilly’s scale. A factor analysis found four factors: 1. absorption or derealization 2. depersonalization 3. segment amnesia 4. in situ amnesia
(Segment amnesia differs from in situ amnesia because you wake up to it at that moment in the in situ vs the segment case.)
We have 20-30 people who score very high on hypnotizability.
Colin Ross finds the same factors as our factors 1 and 2, but he finds only one amnesia factor where we find two.
The correlation between DES and Harvard ranges .05 to .18. Are the high hypnotizables related to high dissociatives, with others not related? A scatter plot did not reveal that.
FFT EEG bands during baseline for high and low dissociation Ss find no differences for high and low dissociative subjects. We conclude that dissociation and hypnosis are two orthogonal processes.
Now we are beginning to look at the pathways that lead one to become highly hypnotizable or dissociative.
Ian Wickramasekera: Have you introduced threat to high or low DES people? Answer: High and Low DES people with happy and unhappy imagery tasks do the opposite, with the dimensionality measure. With emotionality you don’t see stable baseline differences, you see reactivity differences.
A. Barabasz: I think the DES isn’t a good measure of dissociation in hypnosis which is voluntary and not pathological.
D. Spiegel: Sabourin’s study found more theta in left frontal during hypnosis, whereas you found less. Answer: That’s why I don’t know what to do about the state effects.
J. Crawford: Sabourin had Ss doing tasks, so they may have been more active than yours.

Dabic-Jeftic, Mirjana; Barnes, Graham (1993). Event-related potentials (P300) during cognitive processing in hypnotic and non-hypnotic conditions. Psychiatria Danubina, 5 (1-2), 47-61.

In this study authors investigated to find out if there were any specific changes of event related potentials in subjects before hypnosis, entering hypnosis, in deep hypnosis and leaving hypnosis, and to compare mental activities of subjects such as capability of correctly calculating and remembering the exact number of unexpected stimuli delivered by stimulator with their verbal or nonverbal reports during any of the conditions investigated. The methodology was of testing the cognitive evoked potentials elicited by auditive stimuli, using the oddball paradigm. Obtained results show that the most constant values of shortest latency and highest amplitudes of the cognitive waves, especially P300 were found during deep hypnosis. All five subjects in the investigation answered with the exact number of delivered target stimuli only after deep hypnosis. Conversely, in all other conditions their answers were approximate to the correct number of delivered target stimuli. (Author abstract.)

In this experiment, 5 adult volunteers were told to attend to one of two tones delivered through headphones. The tones were randomly delivered but one occurred 85% of the time (the ‘frequent, non-target tone’) and the other occurred 15% of the time (the ‘rare, target tone’). The subjects were to notice, remember, and count the target tone. Measures were taken during five periods: pre-hypnosis, entering hypnosis, deep hypnosis, leaving hypnosis, and post-hypnosis.
Some subjects had extensive hypnosis experience prior to the experiment; others had little.
The EEG P300 wave was sensitive to condition. Latency of P300 was significantly shorter in deep hypnosis compared with other periods. Higher amplitude of P300 also occurred during deep hypnosis compared with other periods. (Notes taken from secondary reference, Ericksonian Newsletter.)

In this experiment, 5 adult volunteers were told to attend to one of two tones delivered through headphones. The tones were randomly delivered but one occurred 85% of the time (the ‘frequent, non-target tone’) and the other occurred 15% of the time (the ‘rare, target tone’). The subjects were to notice, remember, and count the target tone. Measures were taken during five periods: pre-hypnosis, entering hypnosis, deep hypnosis, leaving hypnosis, and post-hypnosis.
Some subjects had extensive hypnosis experience prior to the experiment; others had little.
The EEG P300 wave was sensitive to condition. Latency of P300 was significantly shorter in deep hypnosis compared with other periods. Higher amplitude of P300 also occurred during deep hypnosis compared with other periods. (Notes taken from secondary reference, Ericksonian Newsletter.)
EEG was recorded monopolarly at frontal (F3, F4), central (C3, C4) and posterior (in the middle of O1-P3-T5 and O2-P4-T6 triangles) derivations during the hypnotic induction of the Stanford Hypnotic Clinical Scale (SHCS) and during performance following suggestions of hypnotic dream and age-regression as expressed in the before-mentioned scale. 10 low-hypnotizable and 9 highly-hypnotizable and right- handed female students participated in one experimental session. Evaluations were Fast- Fourier spectral analyses during the following conditions: waking-rest in eyes-open and eyes-closed condition; early, middle, and late phases of hypnotic induction; rest-hypnosis in eyes closed condition; hypnotic dream and age regression. After spectral analysis of 0 to 44 Hz, the mean spectral amplitude estimates across seven Hz bands (theta 1, 4-6 Hz, theta 2, 6-8 Hz; alpha 1, 8-10 Hz; alpha 2, 10-13 Hz; beta 1, 13-16 Hz; beta 2, 16-20 Hz; beta 3, 20-36 Hz) and the 40-Hz EEG band (36-44 Hz) for each experimental condition were extracted. In eyes-open and -closed conditions in waking and hypnosis highly-hypnotizable subjects produced a greater 40-Hz EEG amplitude than did low hypnotizable subjects at all frontal, central and posterior locations. In the early and middle hypnotic induction highly-hypnotizables displayed a greater amount of beta 3 than did low hypnotizables and this difference was even more pronounced in the left hemisphere. With posterior scalp recordings, during hypnotic dream and age regression, high hypnotizables displayed, as compared with the rest-hypnosis condition, a decrease in alpha 1 and alpha 2 amplitudes. This effect was absent for low hypnotizables. Beta 1, beta 2 and beta 3 amplitudes increased in the left hemisphere during age regression for high hypnotizable; low hypnotizables, in contrast, displayed hemispheric balance across imaginative tasks. High hypnotizables during the hypnotic dream also displayed in the right hemisphere a greater 40-Hz EEG amplitude as compared with the left hemisphere. This difference was even more evident for posterior recording sites. This hemispheric trend was not evidenced for low hypnotizable subjects. Theta power was never a predictor of hypnotic susceptibility, 40-Hz EEG amplitude displayed a very high main effect (p<0.004) for hypnotizability in hypnotic conditions by displaying a greater 40-Hz EEG amplitude in high hypnotizables with respect to lows. NOTES In the Discussion section, the authors indicate that they have no idea why they didn't replicate results of other theta studies, including their own, except maybe due to complex interaction among personality, subject selection, situation-specific factors, and hypnotizability. They observe that the alpha results conform with previous findings (p. 163). Beta bands were sensitive. Highs showed left-hemisphere prevalence in all beta bands during age regression; they also showed hemispheric balance in the hypnotic dream condition. Beta 3 amplitude was also greater among highs than lows. "among high hypnotizables, beta 3 amplitude in the early hypnotic condition was greater in the left hemisphere as compared to the right and as the hypnotic induction proceeded hemisphere balancing, with reduced beta 3 amplitude, was displayed. This result appears in agreement with the predictions of the neurophysiological model proposed by Gruzelier et al. (1984) and Gruzelier (1988) as well as with other studies in which beta rhythm was found to discriminate performances between high and low hypnotizables (e.g., Meszaros et al., 1986, 1989; Sabourin et al., 1990)" (p. 163-164). 40 Hz amplitude was higher in highs and increased in right hemisphere during the hypnotic dream, especially in posterior areas. "This pattern of hemispheric activation may be interpreted as an expression of the greater right-hemisphere activation and of the release of posterior cortical functions during the hypnotic dream and is compatible with the predictions of the Gruzelier model of hypnosis, however, the results obtained in this study for 40-Hz EEG amplitude failed to reveal an inhibition of the left-hemisphere activity with the progress of the hypnotic induction" (p. 164). (They note that De Pascalis & Penna, 1990, agreed with the Gruzelier 1988 model: highs in early induction had increase of 40-Hz in both hemispheres, but as induction proceeded they had inhibition of left and increase in right hemisphere activity. In this current experiment, only beta 3 showed the hemispheric trend of Gruzelier's model. They cite other details of current study, p. 164, not consonant with Gruzelier.) "The 40-Hz EEG rhythm, which according to Sheer (1976) is the physiological representation of focused arousal, appeared to discriminate between differential patterns of high and low hypnotizables. Both during hypnotic induction and during hypnotic dream and age regression highly hypnotizables exhibit greater 40-Hz EEG amplitude with respect to the lows. These findings support the validity of the assumption that hypnosis is characterized by a state of focused attention (Hilgard, 1965) and that 40-Hz EEG activity reflects differential attentional patterns among subjects high and low in hypnotizability. On the basis of these findings it would appear that 40-Hz EEG and beta 3 spectral amplitudes may prove to be useful measures of individual hypnotizability" (p. 164). Gruzelier, John; Warren, Kristen (1993). Neuropsychological evidence of reductions on left frontal tests with hypnosis. Psychological Medicine, 23, 93-101. Individuals with high and low susceptibility to hypnosis were compared in a baseline condition and after instructions of hypnosis on tests of anterior left and right hemispheric functions of word fluency to letter categories, word fluency to semantic categories, design fluency and bilateral finger tapping dexterity. With hypnosis high susceptibles showed a reduction in word generation to letter categories, no significant change in word generation to semantic categories, an improvement in design fluency, and bilateral reductions in finger tapping dexterity. Low susceptibles showed the opposite changes except for the improvement in design fluency. These results, together with correlational results, were interpreted as evidence of central inhibitory processes, particularly of the left hemisphere, in response to instructions of hypnosis in high susceptibles. NOTES The authors discussion of their study includes the following statements. "The main result of the study was the differential influence of instructions of hypnosis on high and low susceptibles for word fluency to letter designated categories, as distinct from semantic categories, and design fluency" (p. 98). "The absence of effects of hypnosis on word generation to semantic categories (left fronto-temporoparietal) versus letter categories (left frontal) has a bearing on evoked potential evidence (Gruzelier et al. 1987). Bilateral comparisons at temporal lobe and central locations showed that high susceptibles were characterized by asymmetric changes in evoked potential amplitude (N116 component) with hypnosis. Activity at the central electrodes was compatible with a left-to-right hemispheric shift of function, but this was not the case at the temporal electrodes. Instead of an inhibition of left temporal activity with hypnosis activation was maintained. Maintenance of activity in the left temporal lobe follows consideration of the fact that hypnosis requires sustained attention to the voice of the hypnotist, which is predominantly a left temporal function" (p. 99). "The absence of differences in the pre-hypnotic condition between high and low susceptibles indicates that hemisphericity _per se_ may not be a factor that characterizes susceptibility. The fact that lateral differences were found in some experiments (e.g. Gruzelier et al. 1984; Gruzelier & Brow, 1985) but not others (e.g. Cikurel & Gruzelier, 1990; McCormack & Gruzelier, 1993) may indicate that such effects, when apparent, were secondary to another factor such as cognitive flexibility as conceptualized by Crawford (1989)" (p. 99). 1993 Jutai, Jeffrey; Gruzelier, John; Golds, John; Thomas, Martin (1993). Bilateral auditory-evoked potentials in conditions of hypnosis and focused attention. International Journal of Psychophysiology, 15, 167-176. Brain event-related potentials (ERPs) evoked by auditory stimulation were used to study cerebral hemispheric activity during hypnosis. ERPs were recorded from bilateral central (C3 and C4) and temporal (T3 and T4) scalp locations in response to tone pips in 6 medium-high and 6 low-susceptible subjects in three conditions: baseline (tones only), hypnosis (tones plus hypnotic induction), and a focused attention control (tones plus a newspaper story read by the hypnotist). Task asymmetries were individually adjusted for baseline asymmetries. Responses from central locations did not differentiate hypnosis from focused attention for either group. The same was true of temporal locations for the low-susceptible group. The predominant temporal lobe pattern for both conditions and groups was larger left than right responses. The exception was the hypnosis condition for the medium-high susceptible group where there was an increase in responses in the right temporal lobe. Brain event-related potentials (ERPs) evoked by auditory stimulation were used to study cerebral hemispheric activity during hypnosis. ERPs were recorded from bilateral central (C3 and C4) and temporal (T3 and T4) scalp locations in response to tone pips in 6 medium-high and 6 low-susceptible subjects in three conditions: baseline (tones only), hypnosis (tones plus hypnotic induction), and a focused attention control (tones plus a newspaper story read by the hypnotist). Task asymmetries were individually adjusted for baseline asymmetries. Responses from central locations did not differentiate hypnosis from focused attention for either group. The same was true of temporal locations for the low-susceptible group. The predominant temporal lobe pattern for both conditions and groups was larger left than right responses. The exception was the hypnosis condition for the medium-high susceptible group where there was an increase in responses in the right temporal lobe. The influence of an extremely-low-frequency (ELF) magnetic field on the bioelectrical processes of brain and performance was studied by EEG spectral analysis, auditory-evoked potentials (AEP), reaction time (Roletaking) and target-deletion test (TDT). Fourteen volunteers were exposed for 15 min to an intermittent (1 s on/off) 45- Hz magnetic field at 1000 A/m (1.26 mT). Each person received one real and one sham exposure. Statistically significant increases in spectral power through alpha- and beta- bands, as well as in mean frequency of the EEG spectrum were observed after magnetic field exposure. Field-dependent changes of N1OO were also revealed. No changes in the amplitudes or latencies of the earlier peaks were observed. No direct effects on Roletaking, nor on TDT performance were seen. However, practice effects on Roletaking (decrease of Roletaking in the course of the test-sessions) seemed to be interrupted by exposure to the magnetic field. Nishith, Pallavi; Barabasz, Areed F.; Barabasz, Marianne (1993, October). Effects of Alprazolam and hypnosis: EEG spectral decomposition and transient experience. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, Arlington Heights, IL. NOTES We wanted to test Hilgard's neodissociation theory and Crawford's and my ideas about theta reflecting processing dissociation where environmental stimuli are ignored. Hypothesis: highs would show greater EEG theta in hypnosis than lows when exposed to a suggestion to recreate alprazolam (trade name Xanax) effects. We demonstrated hypnosis to groups, discussed it, administered the Harvard, took highs and lows and then tested them with Stanford C; got 20/group, matched for age, gender, and handedness. Assigned 10/cell, in drug or placebo (double blind) conditions. Tested females to make sure they weren't pregnant. Ingested the placebo or drug, waited 1 hour; took 5' waking EEG while they were asked to focus on "feelings of relaxation brought on by the drug." Interviewed them (see our chapter in Fromm & Nash book) to determine their transient mood states during the 5' period, plus gave them POMS tension/anxiety questions. Results of first study: analyzed for hypnotizability x placebo x drug condition. EEG Theta was reduced in hypnosis; hypnotic ability showed no effects. Highs maintained higher beta in alprazolam drug condition (vigilance). Study 2 counterbalanced conditions: Waking Hypnosis Hypnosis with a suggestion to recreate alprazolam effects. Used Ss who actually had taken Alprazolam participated in the experiment four days later; induction was a tape recorded version of the Stanford Clinical Scale. Suggestion: imagine taking a dose twice as high as you had before. EEG and transient experience data were collected as before. 2 x 3 Manova's were computed. 1. Theta was higher for highs than lows at p<.01 for both the hypnosis and hypnosis with drug effects suggestion conditions. 2. Alpha - had the same findings as for theta. (and same results as in our Antarctica study). 3. Beta was significantly higher for both high and lows in waking vs hypnosis conditions at all but the T4 site where beta was highest in the two hypnosis conditions only for the highs. 4. POMS analysis: mean tension/anxiety scores were significantly lower for highs in both the alprazolam and hypnotic suggestion conditions. Both highs and lows showed more theta in hypnotized than in waking conditions. Failure to find differences between groups differing in hypnotizability may be because highs were so good at creating the alprazolam effect that they may have desynchronized theta. 1992 Barinaga, Marcia (1992). Giving personal magnetism a whole new meaning. Science, 256, 967. NOTES Cited in Noetic Sciences Review, Autumn, 1992. This geobiologist has discovered that the human brain contains billions of tiny magnets--some 7 billion of them, each so small that their total weight is only one/millionth of an ounce. In magnetite- containing bacteria, the crystals are used as a compass needle which orients the bacteria with respect to the Earth's magnetic field. In birds, bees, and fish, where concentration of the mineral is a few orders of magnitude higher than he found in the human brain, it is used as a navigational aid. He plays down the possible connection to weak electromagnetic fields that supposedly cause cancer (unless fields could induce very weak electrical fields inside the cells, disrupting cellular function). Other possible interpretations: a means for cells to store excess iron, or part of a magnetic sensing system, or a vestigial system left over in evolution from when we were more directly connected with the earth's magnetic field and may have relied on it for navigation or migratory movement. Miller, Scott D.; Triggiano, Patrick J. (1992). The psychophysiological investigation of multiple personality disorder: Review and update. American Journal of Clinical Hypnosis, 35, 47-61. NOTES A review and methodological critique. Updates Putnam, 1984. Currently, psychophysiologic differences reported in the literature include changes in cerebral electrical activity, cerebral blood flow, galvanic skin response, skin temperature, event- related potentials, neuroendocrine profiles, thyroid function, response to medication, perception, visual functioning, visual evoked potentials, and in voice, posture, and motor behavior. Reviews the new research on the psychophysiological investigation of MPD from published, unpublished, and ongoing studies, and attempts to place current findings into a conceptual framework. Authors note results from unpublished and ongoing studies and include a critical analysis of current research methodology as well as suggestions for future research. 1991 Brown, Peter (1991). Ultradian rhythms of cerebral function and hypnosis. Contemporary Hypnosis, 8, 17-24. As a consequence of his observations of the clinical work of Milton Erickson, Ernest Rossi has proposed an 'ultradian rhythm theory of hypnosis'. Rossi demonstrated that the spontaneous changes in cognition, affect and behaviour which occur as part of the ultradian cycle (which Erickson referred to as 'the common everyday trance') are similar to the changes which occur during hypnosis. A review of studies of the phasic changes in hemispheric function suggests that ultradian changes do parallel the changes found in hypnosis. NOTES Falling asleep and waking up are regulated by two separate mechanisms rather than being opposite poles of one mechanism (Winfree, 1980). Kleitman (1961) suggested a 90-min cycle, the basic rest-activity cycle (BRAC). In addition to physiological alterations, there are alterations in cognition, mood and behavior (Rossi & Cheek, 1988); vigilance (Okawa, Matousek & Petersen 1984); peripheral blood flow (Ramano & Gizdulich, 1980); respiratory amplitude (Horne & Whitehead, 1976); visual evoked potentials (Zimmerman, Gortelmeyer & Wiemann, 1983); pupillary diameter, stability and reactivity to light, and saccadic eye movements (Lavie & Kripke, 1981). These diurnal variations may relate to hypnotic behavior. There is a recurring increase in daydream and fantasy, as well as visual imagery (Kripke & Sonnenschein, 1978). "There is evidence for a parallel recurring cognitive and emotional cycle with increased emotional responsiveness and a more subjective cognitive processing of information (Evans, 1972; Holloway, 1978; Overton, 1978; Thayer, 1987). Subjects appear to repeat the cycle approximately 16 times per day, with a range of 70-120 minutes. Kripke and Sonnenschein (1978) noted that the subjects were personally unaware of any repeating cycle in their mental lives" (p. 19). The brainstem arousal mechanisms seem to be implicated in periodic changes in the EEG. Ultradian rhythms are "more easily detected under conditions of increased sleep need, reduced external performance demand and lowered motivation to focus externally (Broughton, 1985)" (p. 20). Sterman (1985) observed that the rhythm was most marked in resting state and disappears during complex visuomotor tasks. Relationship of EEG patterns to attentional patterns indicate there may be two different forms of attention, one for focused awareness (often thought to be associated with trance state) and the other a generalized vigilance (which would be reduced in hypnosis). Ultradian changes in consciousness reflected in the EEG may suggest increased internal absorption associated with visual imagery, a feature of the trance state. "There has recently been a partial direct confirmation of Rossi's hypothesis. Aldrich and Bernstein (1987 [International Journal of Clinical and Experimental Hypnosis]) reported a bimodal distribution of Harvard Group Scale Hypnotic Susceptibility (HGSHS) scores when they are done at different times throughout the day. They note the parallel of the changes in HGSHS scores and the circadian variations in body temperature which suggest changes in hypnotic responsiveness coinciding with the fluctuations of physiological rhythms. "Other support comes from some highly original work involving breathing rhythms. There are cyclic alterations in relative air flow between the left and right nostrils with an average period of 2-3 hours (Hasegawa & Kern, 1977). This nasal ultradian rhythm is correlated with an increase in contralateral cerebral hemispheric activity (Werntz, Bickford, Bloom & Shannahoff-Khalsa, 1981, 1983; Klein, Pilon, Prosser & Shannahoff-Khalsa, 1986). The alterations in hemispheric function do appear to be related to changes both in the style of cognition, particularly in an increase in vivid visual imagery, and in performance on specific tasks (Klein et al., 1986). Thus these studies support the notion of an ultradian rhythm of cerebral function which is associated with characteristic physical manifestations mediated by the autonomic nervous system. Whether or not these changes are directly related to the findings reported by Aldrich and Bernstein has yet to be established" (p. 21). The authors conclude that "the most consistent evidence for ultradian rhythms is demonstrated by the mechanisms of the hypothalamic-limbic system and by brain-stem mechanisms that regulate arousal and attention processes (Parmeggiani, 1987); neuroendocrine regulatory mechanisms (Follenius, Simon, Brandenberger & Lenzi, 1987) and autonomic nervous system function (Bossom, Natelson, Levin & Stokes, 1983; Gordon & Lavie, 1986). These studies also suggest an ongoing dynamic interaction between cortical and subcortical structures throughout the ultradian cycle (Parmeggiani, 1987), and suggest that these interactions may be of great significance in hypnosis" (p. 21). Graffin, N. W. (1991, October). EEG concomitants of hypnotic susceptibility and hypnosis (Dissertation, Pennsylvania State University). Dissertation Abstracts International, 52 (4), 2296. "Many previous studies of EEG and hypnosis were completed prior to development of spectral analysis and typically included data from a limited number of electrode sites. The categorization of subjects as high and low hypnotizables was often done inappropriately, and disparate findings were obtained. In this study, subjects scoring 10 or more and 3 or less on the Stanford Hypnotic Susceptibility Scale, Form C were defined as high and low respectively. EEG was monitored during resting baseline, mental arithmetic, and mental spatial rotation, and before, during, and after hypnotic induction. EEG was recorded monopolarly at frontal (F3,F4), parietal (P3,P4), temporal (T3,T4), and occipital (O1,O2) derivations, and data were fast Fourier analyzed. Mental arithmetic and mental spatial rotation did not produce differential hemispheric activation. High hypnotizables had greater frontal and temporal theta at baseline than lows. All subjects showed increases in parietal and occipital theta during hypnotic induction. During prehypnotic induction baseline, highs had greater parietal and occipital theta than lows, but this different was smaller after induction. Baseline temporal alpha was greater for highs than lows, but after hypnotic induction, all subjects had less alpha at all sites than before induction. Increases in alpha at all sites for all subjects occurred during hypnotic induction. Beta activity was unrelated to susceptibility but was greater in waking than in hypnotic states for all subjects at all sites. Increases in alpha at all sites for all subjects occurred during hypnotic induction. The theta activity observed suggests that high hypnotizables have a greater capacity for selective attention and imagery and that during hypnosis all subjects experience enhancement of these abilities. The alpha results may suggest an increase in the focusing of subjects on internal processes during hypnosis and greater scanning of the environment after induction" (p. 2296). Lubar, J. F.; Gordon, D. M.; Harrist, R. S.; Nash, M. R.; Mann, C. A.; Lacy, J. E. (1991). EEG correlates of hypnotic susceptibility based upon fast Fourier power spectral analysis. Biofeedback and Self-regulation, 16, 75-85. Examined whether there were differences between high and low hypnotic susceptible subjects based upon fast Fourier power spectral analysis of the EEG recorded both before and during hypnotic tasks. Significant differences were obtained based upon EEG recording electrode location, EEG frequency within six different frequency domains, and hypnotic tasks. However, no main effect differences were obtained based upon hypnotic susceptibility. In contrast to some evoked potential studies in which a few differences have been obtained based on hypnotic susceptibility, the lack of any EEG differences in this study even when positive and negative hallucination tasks were employed may have implications for the role of the neocortex in mediating hypnotic phenomena. NOTES When this study was presented at the annual meeting of the Society for Clinical and Experimental Hypnosis in 1988, in Ashville, the authors remarked that, "Since EEG comes from cortex, the results might be due to subcortical levels. Therefore one should look at cerebral blood flow and metabolism." 1990 Badia, Pietro (1990). Memories in sleep: Old and new. In Bootzin, Richard R.; Kihlstrom, John F.; Schacter, Daniel L. (Ed.), Sleep and cognition (pp. 67-76). Washington, DC: American Psychological Association. NOTES Reviews literature. Conclusion: First, with reinforcement for responding, control of learned behavior can be maintained reliably by stimuli presented during sleep. Second, when stimuli are presented 4 min or more apart, behavioral control results in little or no change in sleep structure, in daytime sleepiness, or in perceptions of sleep quality. Neither perceived wakefulness nor wakefulness as it is scored on the sleep record are necessary for responding, although stimulus/response events typically result in brief EEG or EMG change. Third, within-subject, within-night variance in responsiveness is complexly related to time of night, sleep stage, and REM/NREM cycle. De Pascalis, Vilfredo; Penna, Pietronilla M. (1990). 40-Hz EEG activity during hypnotic induction and hypnotic testing. International Journal of Clinical and Experimental Hypnosis, 38 (2), 125-138. The present sutdy evaluates changes in left and right 40-Hz EEG production for 19 high and 20 low hypnotizable female Ss during the hypnotic induction and the administration of the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) of the Weitzenhoffer and Hilgard (1962). Scalp recorded 40-Hz EEG density was obtained from the middle of the O1-P3-T5 and O1-P4-T6 triangles. As the hypnotic induction proceeded, high hypnotizable Ss exhibited a shift to greater right-hemisphere activity as compared to a waking-state restcondition. In contrast, low hypnotizable Ss, showed a reduction in left- and right-hemisphere activity. No differences between groups for SHSS:C ideomotor items wereobserved. A main effect for Hypnotizability among SHSS:C imaginative items was found. A Hypnotizability x Hemisphere x Trial interaction was found for both sensory distortion and imaginative SHSS:C items. A comparison was made between low versus high hypnotizable Ss of 40-Hz EEG activity while they passed the same item. The results of these comparisons indicate that differences in brain activity might be partially related to the differences between experiencing a hypnotic suggestion or failing to do so. Significant relationships between 40-Hz EEG production and hypnotizability and 40-Hz EEG production and level of amnesia were also found. Edmonston, William E., Jr.; Moscovitz, Harry C. (1990). Hypnosis and lateralized brain functions. International Journal of Clinical and Experimental Hypnosis, 38, 70-84. Bilateral EEG measures were obtained on 16 high hypnotizable Ss (scores of >8 on the Harvard Group Scale of Hypnotic Susceptibility, Form A, Shor & E. Orne, 1962), while performing hemisphere-specific tasks during hypnosis and a no-hypnosis control condition. Conditions and tasks were presented in counterbalanced order, and Ss served as their own controls. The data call into question the right hemisphere activation interpretation of lateralized brain function during hypnosis; rather, the data suggest a lack of task appropriate activity during hypnosis. The failure to attend to baseline activity measurements and the use of ratios to evaluate interhemispheric lateralization may contribute to potential misinterpretations of data. It is critical that activity changes of the separate hemispheres be taken into account in the interpetative process.
Hughes, Dureen J.; Melville, Norbert T. (1990). Changes in brainwave activity during trance channeling: A pilot study. Journal of Transpersonal Psychology, 22, 175-189.