Abstract
People with schizophrenia (SZ) exhibit persistent deficits in visual processing including reduced contrast sensitivity and poor detection of complex image structure, such as contours. Over recent years accumulating psychophysical evidence indicates that vision in SZ is associated with a reduced influence of spatial context which in turn has been attributed to reduced spatial suppression in visual cortex. Compared to controls, people with SZ do not experience the same reduction in perceived contrast that occurs when targets are embedded in a high contrast background. This appears to be a cortical phenomenon: reduced influence of context is not limited to contrast but carries over to other image attributes (such as orientation) but not others (such as luminance). Finally, although patients poor processing of higher-order image structure has been attributed to differences in perceptual grouping, work from my lab indicates that abnormal processing of context may also contribute to patients’ poor sensitivity for contours. It does this by (a) reducing their sensitivity to local orientation and (b) reducing their ability to discount irrelevant background structure. Taken together these results suggest that abnormal processing of context contributes to a range of visual processing deficits in SZ.
Funding: Funded by the Wellcome Trust