Divided attention abilities in young and old adults.

The literature on divided attention and adult aging has not taken age differences in single-task performance into account, and it has not been able to measure divided attention independently of resource allocation strategies. Two experiments are reported that controlled for these factors. In the first experiment, young (18-23 years) and old (57-76 years) subjects made responses to two simultaneous visual displays. Stimulus durations were manipulated to equate single-task performances, and across different conditions subjects were induced to vary the way in which they allocated resources between the two displays. In the second experiment, response time was the dependent variable; dual-task scores were assessed relative to each subject's single-task scores. No significant age difference in divided attention ability independent of single-task performance level was found in either experiment. The existing literature must be reexamined in light of these issues.