The attentional demands of encoding and retrieval in younger and older adults: I. Evidence from divided attention costs.

Four studies examined the effects of divided attention in younger and older adults. Attention was divided at encoding or retrieval in free recall (Experiment 1), cued recall (Experiments 2 and 3), and recognition (Experiment 4). Dividing attention at encoding disrupted memory performance equally for the two age groups; by contrast, for both age groups, dividing attention at retrieval had little or no effect on memory performance. Secondary task reaction times (RTs) were slowed to a greater extent for the older adults than for the younger adults, especially at retrieval. Age-related differences in RT costs at retrieval were largest in free recall, smaller in cued recall, and smallest in recognition. These results provide evidence for an age-related increase in the attentional demands of encoding and retrieval.