Dual-Task Interference

Dual-task interference is a reduction in performance when two tasks overlap in time, compared with performing them separately. A common experimental finding is slower responding when a person must deal with two tasks at once. The term describes the added difficulty caused by their combination, rather than the difficulty of either task considered alone .¹

One explanation is a processing bottleneck: a particular stage, such as selecting a response, may have to handle one task before the other can proceed. Another explanation is that tasks share a limited amount of processing capacity. Dividing that capacity can slow performance. These are explanatory models, and the evidence does not reduce every instance of interference to one mechanism .¹

The timing of the tasks matters. When their processing overlaps less, interference may diminish. Dual-tasking is also distinct from task-switching, in which a person alternates between activities rather than performing overlapping tasks. Both can impose performance costs and involve cognitive control, but their experimental demands and underlying processes are not identical .¹