Age differences in the effects of perceptual noise.

Elderly (60 to 82 years) and young (18 to 25 years) subjects were tested on a visual task in which noise items were present but did not require processing to test the hypotheses that elderly persons have more difficulty ignoring irrelevent stimuli and suppressing response competition than do younger persons. Tachistoscopically presented displays contained a precued central target letter either alone or flanked by noise items that required (1) a response the same as, or (2) opposite to that required by the target letter, or (3) did not require a response in this task. No evidence was found to support differentially greater response slowing by the elderly due to the presence of irrelevant stimuli. Elderly persons showed significantly less effects of response competition, suggesting that the two groups processed the task information differently. The results suggest that age differences in effects of perceptual noise and response competition are not general phenomena, but depend upon the demand characteristics of the specific task.