EFFECTS OF SIMILARITY AND DURATION ON AGE-DIFFERENCES IN VISUAL-SEARCH

Young and old observers performed a feature search task in which a sin gle target was embedded in five distractors. Target-distractor similar ity was varied quantitatively (along the feature dimension of orientat ion) and display duration ranged from approximately 50-400 ms. Identif ication accuracy was worse on target-absent trials, particularly when distractor similarity was high and display duration brief. An age X du ration interaction on accuracy was found to reflect generalized age de ficits in sensitivity and duration-dependent age differences in bias. Results suggest that an age deficit in the rate of information extract ion produces in the elderly a greater dependence on partial informatio n gained from distractors. Additionally, the additive effects of age a nd similarity have implications for visual search tasks where display size is varied.