Abstract
A single psychophysical experiment evaluated observers' ability to detect visual patterns embedded in noise; effects of stimulus complexity and observer age were also evaluated. Eighteen younger and older observers participated in the experiment (mean ages were 20.3 and 72.6 years, respectively). On any given trial, observers were presented with two successive temporal intervals; a dotted visual pattern embedded in noise appeared in one temporal interval, whereas a completely random spatial distribution of dots appeared in the other. The observers' task was to indicate which temporal interval contained the pattern. For all observers, there were large effects of both stimulus complexity and amount of noise. Plots of pattern detection accuracy as a function of complexity were determined for both younger and older adults. As a group, the younger adults were able to tolerate higher amounts of complexity (than older adults) and still perform at a threshold level of performance (d' = 1.0). Despite this overall difference in performance between the age groups, there was a large amount of interobserver variability, such that the pattern detection performance of some individual older adults matched or exceeded that of a sizeable number of younger adults-aging is therefore not accompanied by a uniform or necessary decline in pattern detection.