In search of an electrophysiological index for psychoticism

We set out to investigate the potential of an EEG-based index for the Eysenckian personality trait of Psychoticism (P). Our study addresses both restful-wakefulness EEG and the use of an EEG activation method (photic driving). A total of 33 volunteer participants provided us with adequate EEG recordings with eyes closed, and of these 28 provided us with useable data for all photic-stimulation conditions. High P (P+) participants, who comprise 25% of the final sample, are clearly differentiated in terms of an alpha/theta power ratio from low P (P-) participants. For P- there is little differentiation in the alpha/theta power ratio across conditions of photic stimulation; for P+, differentiation is quite high, suggesting a differential responsivity. For P+ participants, in marked contrast to P-, the theta oscillatory system is most responsive to a 6 Hz driving frequency.