Aging, dichotic memory and digit span.

Comparisons were made between groups of old and young subjects in a dichotic task. In the first experiment old and young subjects had digit spans representative of their respective populations, and in accord with previous dichotic research younger subjects recalled with greater accuracy. The main effect of group and the Group x Test (ear reported first vs ear reported second) interaction were reliable with both serial and free recall scoring. In the second experiment young subjects were matched to old subjects on the basis of digit span. Matching eliminated the group and Group x Test interaction with seriall recall and the group effect with free recall, suggesting that digit span and dichotic memory are mediated by common mechanisms. Error trends and the Group x Test interactions with free recall revealed that some age related differences persisted even after matching. These differences are discussed in terms of regression artifact and processing capacity.