Binocular rivalry alternation rate declines with age.

The effect of aging on the time of spontaneous perceptual alternation in binocular rivalry was examined in 59 subjects. An earlier study reported the change of alternation time by comparing middle-age and elderly subjects. We also observed age-related prolongation in alternation time by comparing subjects in a lower age group (20-34 years) with those in both a middle-age group (35-49 years) and a higher age group (50-64 years). Aging of visual optical functions such as presbyopia or the reduction of contrast sensitivity has an accelerating effect over age and may not be related to the age-associated monotonic prolongation of alternation time in binocular rivalry. The origin of aging in binocular rivalry is still unclear but a neural interval generator for perceptual switching is suggested.