ABSTRACT
Responses made by human beings typically concern circumscribed aspects of their environments, and so are based upon a small fraction of the information simultaneously made available by their sense organs. This selectivity is a condition of survival, since urgent responses may be slowed by the consideration of irrelevant information. If an analogy exists between stimulus categorization tasks and visual search tasks it should follow that the difficulty of discriminating between relevant and irrelevant information increases with age. In the majority of the population visual acuity deteriorates considerably with advancing age. Models to account for age-decrements in the discrimination of brightness and contrast suggest that differences in the performance of populations of old and young people are better explained by models which assume changes in central perceptual processes than by deterioration in the peripheral receptors. A useful practical outcome of such work will be improvements in the design of visual displays to increase the safety and convenience of an aging population.
