A study of hallucination in normal subjects—II. Electrophysiological data

A group of 20 subjects who reported previously experiencing at least one ‘out-of-the-body’ experience (OBE) and a group of 20 matched controls attempted to induce OBEs in the laboratory while their EEG and skin conductance level were monitored. During this task the OBErs showed a tendency to dissociation of arousal between the two cortical hemispheres as measured by the median frequency of the EEG amplitude spectrum. This dissociation took the form of a relative activation of the right hemisphere towards the end of the experiment. The OBErs also showed a tendency to heightened EEG coherence between hemispheres as compared with controls, greater lability of arousal in terms of skin conductance level, and a dissociation between cortical arousal and self-report measures of muscular tension. These results are interpreted in terms of the hypothesis that relative weakness of inhibitory mechanisms is a basic characteristic of the schizotypal nervous system, leading to lability of arousal and dissociation of different arousal systems.