Biomedical subjects

V De Pascalis

Publications and source records attributed to V De Pascalis.

At least 19 recordsLinked to original sources

PubMed2001

Somatosensory event-related potential and autonomic activity to varying pain reduction cognitive strategies in hypnosis.

OBJECTIVES: The issues of differential effects among cognitive strategies during hypnosis in the control of human pain are under active debate. This study, which employs measures of pain perception, electrocortical and autonomic responses, was aimed at determining these pain-related modulations. METHODS: Somatosensory event-related potentials (SERPs) to noxious stimuli under an odd-ball paradigm were recorded at the frontal, temporal and parietal regions in 10 high, 9 mid, and 10 low hypnotizable right-handed young women, at waking baseline, varying cognitive strategies (deep relaxation, dissociative imagery, focused analgesia) in hypnosis and placebo conditions. The phasic heart rate (HR) and skin conductance response were also recorded. The analysis was focused on the frequent standard trials of the odd-ball SERPs. Repeated measures analysis of variance was conducted to examine the experimental effects. RESULTS: Focused analgesia induced the largest reduction in pain rating, more in the high than low hypnotizable subjects. In high hypnotizable subjects, the N2 amplitude was greater over frontal and temporal scalp sites than over parietal and central sites, whereas in moderately and low hypnotizable subjects, N2 was greater over temporal sites than over frontal, parietal, and central sites. These subjects also displayed a larger N2 peak over temporal sites during focused analgesia than in the other conditions. The P3 amplitude was smaller under deep relaxation, dissociative imagery and focused analgesia in the high hypnotizable subjects. For these subjects, the smallest P3 peaks were obtained for dissociated imagery and focused analgesia over frontal and temporal sites. In contrast, for the P3 peak, low hypnotizable subjects failed to show significant condition effects. In all of the subjects, the skin conductance and HR were smaller during hypnotic suggestions than in the waking state. CONCLUSIONS: The effect of pain modulation is limited to high hypnotizable subjects rather than low hypnotizable ones. Higher frontal-temporal N2 and smaller posterior parietal P3 may indicate active inhibitory processes during cognitive strategies in hypnotic analgesia. These inhibitory processes also regulate the autonomic activities in pain perception.

Adult↗

PubMed2000

Gamma activity in schizophrenia: evidence of impaired network binding?

OBJECTIVES: Gamma ('40 Hz') rhythms may play a role in the integration of sensory processing activity. Impaired temporal integration may be a key feature of the associated disturbances in schizophrenia. This is the first study to examine the time course of Gamma activity induced in response to stimuli in this disorder. METHODS: Gamma activity induced in response to task-relevant and irrelevant auditory oddball stimuli was examined in 35 medicated schizophrenics and 35 age- and gender-matched normal controls. We employed a moving Welch window with short time FFT to examine the time course of Gamma amplitude. The amplitude spectrum for each time point was de-trended to eliminate any contribution of broad spectrum activity (EEG or EMG) to Gamma amplitude. RESULTS: For targets, schizophrenics showed a significant decrease in post-stimulus Gamma response amplitude in left hemisphere and frontal sites and an increase in right hemisphere and parieto-occipital sites (P<0.0009). The abnormalities correlated with PANSS general symptom scores. In the non-targets (at a different latency), schizophrenics showed a widespread Gamma decrease (P<0.0005). CONCLUSIONS: The Gamma findings in non-targets may reflect an abnormality in appropriately processing irrelevant stimuli. This could result in defective processing of the context (integration) of relevant target information.

Adult↗

PubMed2000

Cardiovascular reactivity during hypnosis and hypnotic susceptibility: three studies of heart rate variability.

This paper was designed to examine the relationship between hypnotic susceptibility and cardiovascular measures, especially parasympathetic activity, in 3 separate studies. In these studies, neither heart rate nor heart rate variability differed between the high and low hypnotically susceptible individuals at the initial baseline. Furthermore, in the first study, experimental tasks designed to elicit differential sympathetic and parasympathetic cardiac responses demonstrated no interaction with hypnotic susceptibility. Overall, these 3 studies suggest that hypnotic susceptibility in itself is not associated with parasympathetic aspects of either basal cardiac states or cardiac responses. In addition, a hypnotic induction itself did not differentially influence parasympathetic activity for the high versus low susceptible individuals.

Electrocardiography↗

PubMed2000

Italian norms for the Harvard Group Scale of Hypnotic Susceptibility, Form A.

Norms for an Italian translation of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) by Shor and Orne (1962) are presented. Subjects recruited from 1986 to 1989 were pooled, resulting in a sample of 376 participants (297 women and 79 men). The normative data were generally congruent with earlier normative studies in score distribution, item difficulty levels, and reliability. Women had significantly higher hypnotizability scores and item pass rates than men. The reliability scores of the Italian adaptation of the HGSHS:A were the same as a previously reported Danish sample and higher than a German sample, but lower than those of the Australian, Canadian, and original American samples. These results suggest that the Italian version of the HGSHS:A is an efficient tool for initial hypnotizability screening in an Italian context.

Adult↗

PubMed2000

Italian norms for the Stanford Hypnotic Susceptibility Scale, Form C.

This paper presents norms for an Italian translation of the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C; Weitzenhoffer & Hilgard, 1962). Archival data on hypnosis research subjects recruited over a 10-year period of research on hypnosis were pooled, resulting in an aggregate sample of 356 participants (263 female and 93 male). Score distribution, item difficulty levels, and reliability of the SHSS:C were computed. Of this group, 218 subjects were administered the Harvard Group Scale of Hypnotic Susceptibility approximately 3 weeks prior to administration of the SHSS:C. The remaining 138 subjects received only the SHSS:C. Results suggest that the Italian version of the SHSS:C is a reliable and valid measure.

Adult↗

PubMed1999

Peak gamma latency correlated with reaction time in a conventional oddball paradigm.

OBJECTIVE: To determine whether a relationship existed across trials between evoked gamma and reaction time in a conventional cognitive ERP paradigm. METHODS: Auditory oddball data in 40 normal subjects was examined. A moving Welch window and short time FFT were employed to elucidate the time course of gamma (29 to 45 Hz) activity in each single-trial target ERP. The time point with maximum total gamma amplitude (across all sites) was identified automatically, and the associated amplitude, power and latency of this peak was determined. Spearman's rank correlation was employed to examine the relationship of these measures with reaction time. RESULTS: A highly significant and robust correlation between peak gamma latency and reaction time was found (P = 0.000001). Further frequency analysis revealed that this relationship was primarily confined to the 37 to 41 Hz band. This narrow band finding, coupled with the fact that the finding remained after exclusion of possibly EMG contaminated epochs, indicated that the effect was not due to EMG contamination. No relationship between peak gamma amplitude or power and reaction time was found. CONCLUSIONS: Peak evoked gamma latency was correlated with reaction time and seems likely to have functional significance in relation to stimulus processing.

Adult↗

PubMed1998

Effects of memory load on event-related patterns of 40-Hz EEG during cognitive and motor tasks.

The present study describes a phasic event-related synchronization (ERS) in the gamma band (36-44 Hz) induced by the onset of probe visual stimuli. The experiment consisted of two experimental tasks with high and low memory-load in which a geometrical figure (S1) was held in memory for comparison with a subsequent stimulus (S2). In each task a Go-NoGo paradigm was used with a Same-Different discrimination task. The aim of the study was to examine the influence on 40-Hz ERS of stimulus type ('Same-Different') and of response (Go-NoGo) task as moderated by activation or effort level (high/low memory-load). The investigation was carried out in 27 women. The EEG was recorded from FP1, FP2, F3, F4, P3, P4, O1 and O2 scalp sites referenced to linked earlobes. As a manipulation check for activation level, we recorded heart rate (HR) during the S1-S2 period. A main peak of activity was found around 160 ms with a maximum at occipital sites. The amplitude of this peak was higher in the high memory-load as compared to the low memory-load condition. This difference was manifested mainly at F3 and O2 scalp sites. A larger 40-Hz peak at F3 was also found in the Go compared to the NoGo condition. No 40-Hz ERS differences between Same and Different trials were observed. The HR was found sensitive to the stimulus type showing a greater HR deceleration response to S2 for Same trials, as compared to Different ones. In parallel with 40-Hz ERS response, the HR deceleration was more pronounced for the high memory-load as compared to the low memory-load condition. The results indicate that the 40-Hz ERS is dependent upon both memory-load and motor responding. The influence of memory load on cognitive (Same-Different) and motor response (Go-NoGo) variables is discussed.

Adult↗

PubMed1998

EEG activity and heart rate during recall of emotional events in hypnosis: relationships with hypnotizability and suggestibility.

The purpose of the present research was to find physiological and cognitive correlates of hypnosis, imaginative suggestibility and emotional experiences. After the administration of a standard hypnotic induction, the EEG and heart rate (HR) were recorded during self-generated happy and sad emotions using a relaxation condition as a control. Physiological recordings were also obtained during three eyes-open and eyes-closed baseline periods: (1) waking rest; (2) early-rest in hypnosis (just after the hypnotic induction); (3) late-rest hypnosis (at the end of hypnotic condition). EEG was recorded at frontal (F3, F4), central (C3, C4), and posterior sites (middle of O1-P3-T5 and O2-P4-T6 triangles). Using log transform of mean spectral amplitude, eight EEG frequency bands (4-44 Hz) were evaluated. High hypnotizable subjects, as compared to the lows, produced a higher theta1 amplitude (4-6 Hz) across both left- and right-frontal and right-posterior areas. These subjects also produced smaller alpha1 amplitude (8.25-10 Hz) over both left and right frontal recording sites. High suggestible subjects, during resting conditions, disclosed higher theta2 (6.25-8 Hz) and alpha1 amplitudes in eyes-closed as compared to an eyes-open condition than did low suggestible subjects. High suggestible subjects also showed, in hypnosis-rest condition, higher 40-Hz amplitudes (36-44 Hz) and HR activity than did low suggestible subjects. Hypnotizability and not suggestibility was found to moderate emotional processing: high hypnotizable individuals self-reported greater levels of emotional experiences than did low hypnotizables especially in terms of negative emotion. High hypnotizables, during processing of emotional material, also disclosed opposite 40-Hz hemispheric asymmetries over anterior and posterior regions of the scalp. These subjects during happiness showed an increased production of 40-Hz activity in the left frontal and central regions of the scalp, while during sadness they showed an increased activity in the right central and posterior regions. The hemispheric asymmetries for relaxation condition were similar, but less marked, to those obtained for happiness. No significant interactions involving both hypnotizability and imaginative suggestibility were found for physiological variables considered in this study. This demonstrates that hypnotizability and suggestibility reflect different underlying psychophysiological activities.

Adult↗

PubMed1997

P300 event-related-potential amplitudes and evoked cardiac responses during hypnotic alteration of somatosensory perception.

Ten highly hypnotizable women and 10 women with low hypnotizability were tested in a somatosensory target detection task to evaluate the effects of hypnotic alterations of somatosensory perception on P3 peak amplitude and evoked cardiac response. Stimulus detection task consisted of standard and target electric stimuli delivered with a fixed foreperiod. The P3 peak amplitude of ERPs recorded from frontal, central and temporo-parieto-occipital (posterior) scalp sites and phasic heart rate deceleration response were compared in four conditions: (1) normal attention in waking state, (2) hypnotic obstructive hallucination, (3) hypnotic attention, (4) hypnotic passive attention. High hypnotizable subjects demonstrated significant suppression of P3 peak amplitude to target stimuli in the left frontal and posterior scalp sites during hypnotic obstructive hallucination as compared to a normal attention condition. In this condition P3 suppression was paralleled by a smaller anticipatory heart rate deceleration response to probe stimulus onset. The P3 peak to standard stimuli was found significantly greater in low hypnotizable subjects than for those with high hypnotizability regardless of condition. These findings demonstrate that hypnotically induced obstructive hallucination to somatosensory stimuli involve alterations in neural and autonomic responses and are consistent with a trait conception of hypnotizability.

Adult↗

PubMed1995

Decelerative changes in heart rate during recognition of visual stimuli: effects of psychological stress.

The present study investigated whether the anticipatory heart rate (HR) deceleration response may reflect a pre-attentive process of stimulus registration and how reaction time (RT) and HR responses are influenced by the introduction of a psychological stressor. 60 subjects participated in a signalled RT task with a feedback stimulus containing information on their reaction time and accuracy. Changes in HR, skin conductance (SC) and respiration activity were monitored during performance in two conditions of a visual stimulus recognition task with a fixed foreperiod. In one condition subjects were informed that some electric shocks would be delivered to their right wrist (stress condition); in the other, subjects were simply engaged in the stimulus recognition without the stressor (no-stress condition). Stimuli consisted of geometrical figures and for each trial subjects were required to determine whether a probe stimulus was the same as or different from one of two memory items. Two reliable anticipatory HR decelerations, one preceding the imperative stimulus and the other preceding the feedback signal, were observed. Because the HR deceleration preceding the feedback signal (that did not require the inhibition of any specific motor response) was more pronounced than that obtained for the probe stimulus, it was concluded that HR deceleration response is an expression of stimulus processing rather than response preparation. Reaction times for 'same' stimuli were shorter than for 'different' stimuli. Averaged respiratory activity showed that with the onset of a warning signal subjects inspired and held their breath until they received the feedback signal. The averaged skin conductance data showed two main phasic increases, one after the probe stimulus onset and the other after the delivery of the feedback signal. This was taken to reflect the orienting response to the most significant stimuli.

Adult↗

PubMed1993

EEG spectral analysis during hypnotic induction, hypnotic dream and age regression.

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 hypnotizables; 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.

Adult↗

PubMed1991

Heartbeat perception, instructions, and biofeedback in the control of heart rate.

The present study was designed to examine the possibility that individual differences in heartbeat perception and instructions to control heart rate (HR) may influence the acquisition of voluntary control. Good (n = 20) and poor (n = 20) perceivers of cardiac activity were selected on the basis of their performance according to Whitehead et al. (1977) heartbeat discrimination procedure. Measures of state and trait anxiety (the State-Trait Anxiety Inventory Form X-1 and Form X-2) and Tellegen's Absorption Scale (TAS) were used to assess emotionality and absorptive ability. Good and poor heartbeat perceivers (a) were given non-motivating instructions to try to either increase or decrease their heart rate (HR) with, or (b) without the use of HR-feedback, and (c) were given motivating instructions to try to either increase or decrease their HR with, or (d) without HR-feedback. Heart rate, skin conductance (SC), and EMG activity were monitored. Subjects were also requested to indicate the cognitive strategies used during their HR control training. No relationship between heartbeat perception and state-trait anxiety measures was found. The results did not support the idea that individual differences in heartbeat perception are related to individual differences in HR-control. They did indicate, however, that motivating instructions improve the capacity to increase or decrease HR. Subjects were able to voluntarily increase or decrease their HRs with or without a feedback signal. However, more pronounced HR increases were obtained in the feedback as compared with the no-feedback condition. SC and EMG activity were in accordance with arousal levels demanded by HR decrease and increase tasks. Subjects used cognitive strategies concerning activation responses during HR-increase and relaxation responses during HR-decrease conditions.

Adult↗

PubMed1989

Deutsch's frequency anisotropy and ear advantage in a dichotic test of musical chords.

Deutsch [Music Perception 3(2), 127-154, 1985] outlined an effect of frequency anisotropy occurring in dichotic tests which may challenge the usual interpretation of such tests in terms of functional asymmetry of the cerebral hemispheres. This study is aimed at verifying the relevance of Deutsch's findings in the case of a dichotic test of musical chords. A single choice dichotic chord test was administered to two groups of subjects (N = 20, N = 28) with different levels of musical competence. The results show that the left ear advantage obtained cannot be explained on the basis of Deutsch's effect.

Adult↗

PubMed1989

40-Hz EEG asymmetry during recall of emotional events in waking and hypnosis: differences between low and high hypnotizables.

Sixteen high and thirteen low hypnotizable women, who had participated in our previous study (De Pascalis et al., 1987), were enrolled in a hypnotic session. After the hypnotic induction they were requested to recollect 2 positive and 2 negative personal life experiences. In our previous study subjects performed similar tasks in a waking-state. Hypnotizability was evaluated the first time with the Harvard Group Scale of Hypnotic Susceptibility (Form A) and, a second time, individually, with the Stanford Hypnotic Susceptibility Scale (Form C). The State Trait Anxiety Inventory, Maudsley Personality Inventory, and Tellegen Absorption Scale were administered. Upper-trapezius electromyogram (EMG) and bilateral electroencephalogram (EEG) activities within the 35-45 Hz band were recorded. Self-report rating scores for vividness of visual imagery and emotional feeling of the material recalled were evaluated. The 40-Hz EMG amplitude and the left and right hemisphere 40-Hz EEG densities were obtained. The data collected in hypnosis were compared with those in the waking-state. High hypnotizables, with respect to the lows, displayed significantly lower 40-Hz EEG density in the rest condition. High hypnotizables, while they were in hypnosis, showed an increase of 40-Hz EEG density during emotional recall compared with rest periods. In contrast, low hypnotizables, after hypnotic induction, showed no density change during tasks compared to the rest conditions. Different hemispheric trends were found between groups. Highs showed an increase of 40-Hz EEG density over both hemisphere during positive emotions and a density increase in the right and a density reduction in the left during negative ones. This hemispheric trend was found in waking and hypnotic conditions although in the hypnotic condition more pronounced hemispheric patterns were observed. The Tellegen Absorption Scale was found positively related to hypnotizability and with the level of 40-Hz density increase on the right hemisphere during emotional tasks. High hypnotizables, with respect to the lows, were able to access affects more readily. They also showed a greater hemispheric specificity in waking and hypnotic conditions.

Arousal↗

PubMed1987

Hemispheric activity of 40 Hz EEG during recall of emotional events: differences between low and high hypnotizables.

This study evaluates individual differences in hypnotizability as reflected in waking-state hemispheric engagement during recollection of 3 positively and 3 negatively valenced personal life events. The State-Trait Anxiety Inventory, Maudsley Personality Inventory, Tellegen Absorption Scale and Harvard Group Scale of Hypnotic Susceptibility (Form A) were administered. Electromyogram (EMG) and bilateral electroencephalogram (EEG) activities within the 40-Hz band were recorded during rest and task conditions in 22 high and 21 low hypnotizable women. Self-report rating scores for vividness of visual imagery and emotional feeling of the material recalled were evaluated. The 40-Hz EMG amplitude and both hemisphere 40-Hz EEG densities were obtained. A 40-Hz EEG ratio, as a measure of hemispheric asymmetry, and a hemispheric specificity index were also computed. High hypnotizables showed significantly lower 40-Hz EEG density than low hypnotizables in all experimental conditions. The relationship between lateralization of 40-Hz EEG and emotional processing was moderated by hypnotizability. High hypnotizables, with respect to rest condition, showed an increase of density over both left and right hemispheres during two of the three positive emotional tasks, while they showed a depressed activity over the left and an increased activity over the right during negative emotional tasks. Low hypnotizables, on the other hand, did not exhibit differential hemispheric patterns that could be attributed to different emotional valences. The high group showed greater hemispheric specificity in the predicted direction than the low group. High subjects exhibited greater ratings of absorptive ability and emotional feeling than low subjects. Anxiety and EMG levels did not differ between groups. EMG was dependent on the type of emotion which showed greater activity in the negative emotion condition compared with the positive one.

Adult↗

PubMed1987

Event-related potentials as asymmetry indices of lateralized cognitive processes during music and verbal tasks.

The present study replicates and extends earlier findings by using event-related potentials (ERPs) as a means of providing information about differential hemispheric engagement in cognitive processing. ERPs were recorded from T3, T4, T5 and T6 in response to task-irrelevant tone pips superimposed on white noise, on music and on verbal passages, which are thought to differentially activate the two hemispheres. The latencies and amplitudes of three peaks (N1, P2 and N2) were obtained in 37 women. Task-related ERP asymmetries were found only for the peak amplitude of N2 recorded at posterior-temporal scalp areas, whereas at the anterior-temporal recording, there were no interactional effects. The hemisphere assumed to be most engaged in task processing showed a smaller N2 peak amplitude to tone pips at the posterior-temporal scalp area than the hypothesized unengaged hemisphere. A result common to the three peaks in the ERP was that peak latencies were longer in the music than in the noise condition. Finally, the posterior-temporal areas produced longer N2 peak latencies in verbal and even more in music conditions compared to white noise conditions. No differences in latencies were found between hemispheres during the ongoing cognitive tasks.

Adolescent↗

PubMed1986

Effects of feedback control on EEG alpha asymmetry during covert mental tasks.

EEG alpha (8-12 Hz) was recorded bilaterally from O1-P3 and O2-P4 during two eyes-closed sessions in 40 women. During one session subjects performed two covert right-hemisphere activation tasks and two covert left-hemisphere activation tasks (no-biofeedback condition). During the other session subjects performed the same tasks while trying to control their EEG asymmetries, being provided with EEG asymmetry auditory feedback (biofeedback condition). The ratios of integrated EEG alpha amplitudes were calculated as measure of hemispheric asymmetry, and the number of times that the right and left alpha had the same phase angle was determined as index of hemispheric synchrony (alpha phase index). In both conditions, subjects rated orally after each task their degree of subjective fullfilment of the task. There were significant differences between the EEG asymmetry during right- and left-hemisphere tasks. Significant differences of integrated alpha amplitudes and ratios between the no-biofeedback and biofeedback condition were also found. There was more hemispheric asymmetry in the biofeedback than in the no-biofeedback condition, and a significantly higher alpha phase index. There was no correlation between fullfilment ratings and alpha ratios in the no-biofeedback condition, but there was such correlation during right and left hemisphere tasks in the biofeedback condition. The study demonstrated that biofeedback regulation and covert mental activity can have effects on EEG alpha asymmetry which are cumulative.

Alpha Rhythm↗

PubMed1986

EEG alpha asymmetry: task difficulty and hypnotizability.

Parieto-occipital EEG alpha was recorded bilaterally, while 20 high- and 20 low-hypnotizable women performed one left-hemisphere and one right-hemisphere task of low difficulty and two other comparable tasks of high difficulty. Every task was performed twice, once with eyes open and once with eyes closed. All subjects were right-handed. The tasks were originally selected to be of high and low difficulty. The subjective rating of task-difficulty was also evaluated. The integrated amplitude alpha and the alpha ratio (R-L/R + L) were the dependent variables. The highly hypnotizable women showed significantly higher alpha amplitude in eyes-closed condition than the low scorers; this difference disappeared during task performance and in the eyes-open condition. The left-tasks showed lower alpha amplitude in both hemispheres than right-tasks and baseline. The right-hemisphere alpha amplitude was lower than left in all experimental conditions. On tasks of high and low difficulty there was different hemispheric behavior on right and left tasks. Performance reflecting the right and left hemispheres in the low-difficulty condition showed no changes between baseline, right- and left-tasks, while under high difficulty there was a decrease in alpha amplitude in the right and even more marked decrease in the left hemisphere during left-tasks. The pattern of task effects for ratio scores was the same as for alpha amplitude, however, despite the analysis of alpha scores, an interaction of hypnotizability X task-difficulty was detected. The highly hypnotizable women showed less negative alpha ratio during a task of low difficulty than during tasks of high difficulty; the reverse was true for the low-hypnotizable women. Finally, the highly hypnotizable subjects showed less subjective difficulty during performance than the low scorers.

Adult↗