AGE-DIFFERENCES IN SAME-DIFFERENT JUDGMENTS AS A FUNCTION OF MULTIDIMENSIONAL SIMILARITY

Age deficits in visual search often are attributed to difficulties in comparing display items to target representations. In the presence-abs ence search paradigm, however, these comparisons are frequently confou nded with age differences in the latency and velocity of saccadic eye movements, reductions in the useful field of view (FOV), and retention of information concerning previously searched locations. To circumven t these shortcomings, 20 young and 20 older adults were compared in th e speed of their same-different judgments of two perifoveal stimuli. T he two stimuli were either identical or varied along one or more of th e dimensions of size, shape, and color. In both age groups, RT for cor rect ''different'' judgments increased with stimulus similarity, an ef fect which was more pronounced in the elderly subjects. Results sugges t that age differences in free search are due, in part, to an age-rela ted decline in the speed of evaluating object congruence.