Aging and switching the focus of attention in working memory: age differences in item availability but not in item accessibility.

OBJECTIVES To investigate age differences in working memory processing, specifically the accuracy of retrieval of items stored outside the immediate focus of attention. METHODS Younger and older adults were tested on a modified N-Back task with probes presented in an unpredictable order (implying also that some trials necessitated a switch in the focus of attention and others that did not). RESULTS Older adults showed intact item accessibility, that is, after taking general slowing into account, older adults were as fast as younger adults in locating the item in working memory. We found age differences, however, in item availability: Older adults were less likely to correctly retrieve items stored outside the focus of attention. Smaller age differences in availability were also found for items stored inside the focus of attention. DISCUSSION These results strongly suggest that item availability is a cognitive primitive that is not reducible to more basic constructs such as item accessibility or simple speed of processing.