On the difficulty of task switching: assessing the role of task-set inhibition.

This study assessed whether or not the difficulty of task switching stems from previous inhibition of the task set. A predictable sequence of univalent stimuli (affording performance of one active task) and bivalent stimuli (affording performance of two tasks) was used in two experiments. Experiment 1 used an alternating-runs paradigm (AABB) and Experiment 2 used a strictly alternating sequence (ABAB). The critical variable was whether the incentive for task-set inhibition was strong (on bivalent trials) or weak (on univalent trials). The question was whether it would be more difficult to switch to a task that previously needed to be inhibited than to a task that did not need to be inhibited. This pattern was not observed in either experiment. Thus, the data provide no evidence that task switching is difficult because of the need to overcome recent task-set inhibition.