Ideomotor-Compatible Tasks Partially Escape Dual-Task Interference in Both Young and Elderly Adults

Under most circumstances, it is not possible to carry out central processing for 2 tasks at the same time; effectively there is a bottleneck. Nevertheless, in 2 experiments it is demonstrated here that both younger and older adults are able to partially bypass the bottleneck in a psychological refractory period procedure, even without extensive training, when the 2nd of the 2 tasks is a saccade or a body tilt in the direction of rotation of a visual stimulus. Consistent with earlier research, the findings showed that younger adults can bypass when the second task has ideomotor-compatible stimuli and responses. Most strikingly, they demonstrated that bypass can also occur in older adults. Overall, the findings are inconsistent with any categorical claim that younger adults can bypass the dual-task bottleneck whereas older adults cannot. The construct of ideomotor-compatible tasks may comprise 2 quite different classes of experimental procedures.