Dual-task assessment of age differences in automatic process development.

The present experiment assessed dual-task performance in 20 young (mean age 21) and 20 old (mean age 72) adults. Ss first received extensive single-task practice on consistent and varied search tasks. Next, they received dual-task practice in 2 conditions: (a) varied visual search plus varied memory search and (b) consistent visual search plus varied memory search. In the varied-varied condition, young and old adults showed similar dual-task decrements. These results, along with the current data in the literature, suggest that practice may play an important role in determining age-related dual-task differences (or lack thereof). In the consistent-varied condition, young adults attained single-task performance levels, because they had automatized the consistent task. Old adults were unable to match their single-task performance levels, indicating that they were unable to automatize the consistent task.