Absorption and hallucinatory experience

In this paper, we investigate whether the personality trait of Absorption is a predisposing factor for hallucinatory experience. Our participants completed a number of questionnaires, assessing absorption, hallucinatory experiences, subjective experiences along the sleep–wakefulness continuum, paranormal experiences and belief, and dissociation. Our findings are indicative of a common, pseudo‐hallucinatory experiential base, suggesting that absorption can indeed serve as the predisposing factor for hallucinatory experience. In our discussion, we look at the implications of this finding for applied cognitive psychology, focusing on the study of false memories and reality monitoring, and on the study of probability judgement and paranormal belief. Copyright © 2003 John Wiley & Sons, Ltd.     

EEG alpha rhythm, ocular activity and basal skin resistance.

Most hypotheses about the origin of the occipital alpha rhythm stress the specific influence of ocular activity.In this study, the influence of eye-movement frequency and extreme upward deviation of the eyeballs (enlarging the corneo-retinal potential) on occipital alpha activity and basal skin resistance is investigated. Eye-movement frequency did not significantly influence alpha activity and basal skin resistance. On the other hand, extreme upward deviation of the eyeball resulted in alpha activity enhancement and BSR increase. A white noise stimulus, given while the eyeballs were in an extreme upward position lead to a significant decrease in both alpha activity and BSR. However, the influence of the white noise condition was relatively larger on BSR than on alpha activity.The results of this study lead to the hypothesis that the extreme deviation of the eyeballs effects occipital alpha activity in two different ways; one is a direct influence from the eyes, along a low conductance pathway to the occipital region, according to Ennever; secondly, it is proposed that, during the extreme upward deviation of the eyeballs, inhibitory impulses from extra-ocular muscle receptors are sent down to the reticular formation leading to alpha activity increase (e.g. cortical arousal decrease).     

Extraversion,impulsiveness, and EEG alpha activity

Measures of spontaneous EEG activity in the 8–14-Hz band (alpha) obtained while subjects opened and closed their eyes on instruction were related to scores on the EPQ-E scale and scales of narrow and broad impulsiveness. Subjects with high scores on narrow impulsiveness were found to show less alpha activity than subjects with low scores. No significant relationships with alpha activity emerged for the other personality scales. It is concluded that impulsiveness rather than EPQ-E is the major correlate of differences in EEG-defined arousal.     

Differences in EEG alpha activity related to giftedness

In three experiments, differences in EEG alpha activity between gifted (mean IQ = 137) and average (mean IQ = 105) individuals were investigated. EEG activity was monitored over 16 scalp locations. A fast Fourier transform was performed on 15 artifact-free 2-second chunks of data to derive a spectral power average in the alpha band (7.5–13 Hz). In the first experiment, EEG of gifted and average individuals during two relaxation phases—eyes closed and eyes open—was recorded. Gifted individuals showed higher EEG alpha power only while resting with eyes open. In the second experiment, gifted and average individuals solved two problems that were divided into phases of problem solving and preparing for problem solving (reading, making a plan of how to solve the problem). Significant differences were obtained only for the problem-solving stages. Gifted individuals in comparison with average ones showed higher alpha power (less mental effort) while solving the two problems. The third experiment investigated whether the lower mental activity displayed by gifted individuals was related to their ability to form more abstract schemata. For that purpose EEG was recorded while gifted and average individuals memorized lists of words and pictures that either allowed, or did not allow, for classification into more abstract categories. For both types of lists, gifted individuals displayed higher alpha power than average ones. The results obtained confirm the hypothesis that the higher EEG alpha power during information processing displayed by gifted individuals may derive from the nonuse of many brain areas not required for the problem at hand.     

The unimportance of experimenter-bias in sensory deprivation research.

3 graduate student experimenters' expectations about the stress reaction of 24 subjects to sensory deprivation or to an ambulatory control condition were factorially manipulated. No significant differences were found for experimenters' expectation, directly or through interaction. Results were interpreted as a refutation ofthe assumed pervasiveness of experimenter-bias effects.     

Patterns of EEG alpha during word processing and relations to recall

EEG alpha activity was monitored during word presentation in a single trial cued-recall task. Initial post-word changes in alpha were related to a dimension of word meaning (arousal-neutral) while subsequent alpha asymmetry was a function of encoding instructions (verbal or visual). Initial bilateral reductions in alpha were associated with increased recall, but subsequent asymmetry in alpha was not. The results suggest a two stage pattern of cortical activation associated with memory storage processes.     

EEG alpha asymmetry in dyslexics during speaking and block design tasks

Lateral specialization for speech and spatial construction was investigated in a highly screened group of dyslexic and normal-reading boys, age 9-13, by examining the extent to which their EEG alpha asymmetry changed from one task to the other. EEG was recorded from central, midtemporal, and parietal leads during several minutes of spontaneous narrative speech, and while the child constructed block designs. The dyslexics showed the same strongly task-dependent asymmetry as the normal readers, comparable to that observed in our adult populations. The observations were confirmed with a second independently chosen cohort of subjects. This result is discussed in terms of the constraints it places on models of dyslexia which invoke disorders of lateral specialization and hemisphere integration.     

Hypnagogic imagery and EEG activity.

The relationships between hypnagogic imagery and EEG activity were studied. 7 subjects (4 women and 3 men) reported the content of hypnagogic imagery every minute and the hypnagogic EEGs were classified into 5 stages according to Hori's modified criteria. The content of the hypnagogic imagery changed as a function of the hypnagogic EEG stages.     

EEG alpha asymmetry and creativity

Results of 3 experiments examining the relationship between creativity and left-hemisphere and right-hemisphere EEG activity are reported. Creativity has been hypothesized to involve the use of primary-process cognition, and such cognition is hypothetically accompanied by activation of the right cerebral hemisphere. In light of these hypotheses, we predicted that highly-creative people should exhibit greater right-hemisphere than left-hemisphere EEG activity during creative performance and that this pattern would not be found in less-creative people. All 3 experiments supported this prediction. This difference in asymmetry was specific to creative performance. It was not present during basal recordings or during a non-creative task.     

EEG alpha reactivity and extraversion-introversion

Spectral characteristics of spontaneous EEG and characteristics of the alpha attenuation response (AAR) induced by acoustic stimulation, were analyzed for two groups of subjects selected on the basis of their scores on the extraversion-introversion scale of the Eysenck Personality Questionnaire. While no significant differences were found in basic alpha rhythm, significant differences were manifested in the AAR characteristics. Extraverted subjects habituated to the auditory stimulus while introverts did not. Introverts were generally more responsive to stimulation. The results are discussed in relation to the arousability model proposed by Eysenck and Gray, verifying the relationships with typological dimensions of Superior Nervous Activity, elaborated by the Soviet school.