Effects of noise type and retinal eccentricity on age differences in identification and localization.

Twenty young (M = 24 yrs), and 20 older adults (M = 62 yrs) identified and localized two target letters presented nonfoveally in each of three noise conditions. Targets were presented in isolation, embedded in featurally similar distractors, or embedded in distractors that were featurally similar to the alternate response. Older adults were generally slower to identify targets, particularly in multi-element arrays. Age differences favoring the elderly were found in target-similar identification accuracy, but the young identified targets more accurately in alternate-similar noise. Localization errors were greater among the elderly, who exhibited a bias to localize targets to central array positions. Age differences in noise effects are explained as resulting from ontogenic change in the duration of temporal integration required to encode arrays to the level of a primary detection response (Estes, 1982). The model's predictions were given small-scale validation when visibility was decreased in young adults who then produced performance profiles similar to the elderly.