Aging effects on collinear facilitation.

Normal aging has been shown to alter performance on several suprathreshold spatial tasks such as contour integration and perceptual measures of center-surround interactions. The purpose of this study was to investigate the effects of aging on collinear facilitation. Despite all related lateral interactions that are presumed to involve neural architecture within primary visual cortex, collinear facilitation differs from contour integration and surround suppression tasks in that it is a purely foveal, threshold phenomenon. Collinear facilitation was measured for 20 younger (19-31 years) and 15 older (59-71 years) adults with measures repeated over two identical test sessions. Contrast thresholds were measured for a central Gabor patch in the presence of flankers of varying interelement distances and orientations. A reduced magnitude of facilitation was found for the older observers. Our results demonstrate abnormalities of spatial interactions in older adults.