A demonstration of dual-task performance without interference in some older adults

Highly efficient dual-task processing is demonstrated when reaction time to each of two tasks does not differ between the dual-task situation and the single-task situation. This has been demonstrated reliably in younger adults; nevertheless, the two extant studies of extensive dual-task training did not find evidence for it in any elderly adult. The origins of age-related differences after training were explored in a study in which the stimuli for the two tasks were perfectly redundant although two distinct responses were required. The dual-task situation thus greatly reduced the demands of stimulus categorization while still requiring two response selections and two response executions. After only limited training 8 of 8 younger adults and 5 of 8 older adults showed performance consistent with highly efficient processing. Three older adults failed to show this even after 12 training sessions. The results implicate stimulus categorization more than response selection as an important locus of inefficient dual-task processing, particularly for older adults.