Simultaneous brightness contrast in young and old adults.

The illusion of simultaneous brightness contrast was used to investigate age changes in contrast sensitivity under suprathreshold conditions. Contrary to findings for threshold measures of visual functioning in older adults, the 20 older adults (aged 60-79 yrs.) showed a significantly larger simultaneous brightness contrast effect (p less than .05) than the 20 younger adults (aged 17-26 yrs.). The increase in simultaneous brightness contrast in older adults is attributed to a degeneration of damping fibers in the visual system.