Aging and visual processing: declines in spatial not temporal integration.

Age-related declines in vision are well documented in the literature. In the present study we examined whether changes in spatial or temporal integration contribute to this decline. Younger (mean age of 21) and older (mean age of 745) subjects were asked to identify 2D shapes based on kinetic occlusion information---the accretion and deletion of texture during motion. The results of the first experiment indicated age-related decrements in spatial but not temporal integration. In the second experiment we manipulated the lifetime of motion stimuli to more directly examine temporal integration. The results indicated no differential effect of age on temporal integration. The results considered together suggest age related changes in recovering 2D shape from occlusion are the result of spatial but not temporal integration. Age-related changes in neural inhibition and ACh for regulating spatial integration are proposed as possible mechanisms for this decline.