The influence of perceptual load on age differences in selective attention

The effect of perceptual load on age differences in visual selective attent ion was examined in 2 studies. In Experiment 1, younger and older adults ma de speeded choice responses indicating which of 2 target letters was presen t in a relevant set of letters in the center of the display while they atte mpted to ignore an irrelevant distracter in the periphery. The perceptual l oad of relevant processing was manipulated by varying the central set size. When the relevant set size was small, the adverse effect of an incompatibl e distractor was much greater for the older participants than for the young er ones. However, with larger relevant set sizes, this was no longer the ca se, with the distracter effect decreasing for older participants at lower l evels of perceptual load than for younger ones. In Experiment 2, older adul ts were tested with the empty locations in the central set either unmarked (as in Experiment 1) or marked by small circles to form a group of 6 items irrespective of set size; the 2 conditions did not differ markedly, ruling out an explanation based entirely on perceptual grouping.