Personality and augmenting/reducing in visual and auditory evoked potentials

Previous studies have indicated a relationship between evoked potential augmenting/reducing and extraversion or sensation seeking. However, the proposed mechanism of protective inhibition can account for this fact only if the relationship generalizes across different modalities and response definitions. The present study was designed to test this, using six intensities of visual and six intensities of auditory stimuli along with the EPI and SSS questionnaires.For the visual stimuli, the slope of the P90-N120 amplitude at the vertex correlated significantly with both the extraversion and the disinhibition scales in the way that augmenting/reducing theory predicts. However, over the primary visual area, no component showed the same personality relationship as the vertex wave, and one early component showed the opposite. This result suggests that personality differences in VEPs may reflect different ways of allocating processing resources between primary and association areas, rather than a generalized tendency to inhibit strong stimuli. In the auditory modality, personality differences were not apparent in the amplitude slopes, possibly due to the confluence from primary and association areas in AEPs in the vertex lead. There was a general tendency for latencies to correalte positively with extraversion and disinhibition, in congruence with Eysenck's theory on the biological basis of extraversion.