Contrast detection and discrimination in young and older adults.

Abstract

To determine if age differences in contrast detection thresholds extend to suprathreshold contrast discrimination. Psychophysical contrast detection and discrimination thresholds were determined in 56 adults ranging in age from 22 to 72 years. In experiment 1, thresholds were measured using a two-interval forced-choice procedure across a range of pedestal grating contrasts. In experiment 2, detection and discrimination thresholds were measured at two spatial frequencies and two luminance levels. When normalized to the contrast detection threshold, contrast discrimination thresholds were similar in young and older adults. This result is akin to previous findings for clinical patients with contrast detection deficits. In addition, contrast discrimination in the elderly is independent of mean display luminance as has been found in young adults. Normalized contrast discrimination functions have the same shape in young and older adults and show no change with a 4-fold reduction in luminance.