Altered early visual processing components in hallucination-prone individuals.

Of the nonpathological general population, 0.5% experience one or more visual hallucinations on a regular basis without meeting the criteria for clinical psychosis. We investigated the relationship between a proneness to visual hallucinations in 'normal' individuals and early visual event-related potentials during the perception of faces, Mooney faces and scrambled Mooney faces. Findings indicated that individuals prone to visual hallucinations displayed significantly reduced early event-related potential components (P1, P2, but not N170) over parieto-temporal regions. These findings support previous suggestions that individuals who experience visual hallucinations exhibit abnormal early visual processing resulting from degraded visual input, in this case owing to disruption of low level visual processes.