A DECOMPOSITION OF AGE-RELATED DIFFERENCES IN MULTITRIAL FREE-RECALL

The relative roles of acquisition and forgetting in mediating age-rela ted differences in multitrial learning were evaluated by having 258 ad ults (18 to 94 years of age) complete five study and free-recall test trials of 15 words. Performance across trials was decomposed into (a) gained access, corresponding to the proportion of items recalled on tr ial n+1 of those that were not recalled on trial n (hence tapping proc esses related to acquisition), and (b) lost access, corresponding to t he proportion of items not recalled on trial n+1 of those that were re called on trial n (hence tapping intertrial forgetting). Age-related d ifferences occurred both in gained access and in lost access, although acquisition seemed to play a larger role in mediating age-related dif ferences in learning than did forgetting. Also, a composite measure of processing speed shared 63% or more of the age-related variance in me asures of free recall. The overall pattern of results is consistent wi th the view that age-related decreases in the speed of completing elem entary encoding operations contribute to poorer learning by leading to weaker representations of the to-be-remembered items.