Pre-attentive operation and psychoticism: A P50 event related potential study

On the stipulation that “a theory of personality must be testable” (H. Eysenck), along with the view that the P50 component of the event-related potentials (ERP) indexes pre-attentive operation that reflects thalamocortical and/or reticular activating system (RAS) processes, the present study investigates the association of Eysenck’s personality dimensions, namely psychoticism, extraversion, neuroticism, and lie, with P50 ERP. Sixty volunteers were analyzed (29 males). P50 waveforms were measured through 26 electrode leads during the initiation, inhibition and reproduction condition of the Hayling Sentence Completion test. Extraversion, neuroticism, psychoticism, and lie dimensions were measured by means of the Eysenck Personality Questionnaire. Multivariate analysis of variance revealed that the low psychoticism group had significantly greater amplitudes than the groups with medium and high scores. The differences among the groups reached higher levels of significance in the initiation and the inhibition condition than in the reproduction condition. In the inhibition condition significant differences were located at the frontal leads, whereas in the initiation condition they were scattered throughout the electrode leads. The associations of extraversion, neuroticism and lie scale with P50 were not significant. These results suggest that psychoticism may be related to pre-attentive operation mediated by thalamocortical and/or RAS processes.