The aim of the proposed research is to examine possible neural mechanisms underlying the spatial vision of older humans. Previous research has indicated that many older adults in their 60's to 80's have an impaired ability to see small and intermediate sized objects. This is true even of older people who are free from ocular diseases, suggesting that these visual deficits are a part of the normal aging process. Although there has been much research concerned with describing older people's visual deficits, there has been little research focused on the neural mechanisms underlying these age-related losses. Th experiments proposed here use psychophysical techniques to examine neural mechanisms which may play a role in the vision problems of the elderly. The long-term objectives of this research are three-fold. First, more than pinpointing what visual capacities change in old age, scientists must identify what underlying neural processes are vulnerable to aging. Psychophysical studies are particularly useful in addressing this issue. Second, if we more thoroughly understand mechanisms behind age-related vision problems, we can better predict and identify circumstances in which older people may experience difficulty. Third, it is important to separate, as much as possible, those visual changes that are expected on the basis of aging alone, from those that are symptomatic of ocular disease.