Intentional reconfiguration and involuntary persistence in task-set switching
Switching between different tasks often increases response time compared to repeated performance of a task. This switch cost has been thought to reflect either an executive process of task set reconfiguration or proactive interference from competing task sets. This chapter tries to reconcile these views by showing that switch costs are influenced both by voluntary preparation and involuntary carry-over of inhibition and stimulus-response-bindings from the previous trial. Three experiments are reported in which participants switched between responding to the color and responding to the identity of letters. Switch costs were reduced when participants verbalized each task before the stimulus, compared to when they performed a verbal distractor task, suggesting that intention retrieval sup ported advance reconfiguration. Switch costs increased when the two stimulus dimensions activated incongruent responses and when task switches followed incongruent trials, indicating persisting activation of preceding task sets and persisting inhibition of irrelevant perceptual dimensions, S-R mappings, or both. Findings suggest that voluntary actions are not controlled by a unitary central executive, but emerge from the interaction of separable component processes, some maintaining intentions, others reconfiguring task sets. According to the proposed model, seemingly dysfunctional aspects of cognitive control are manifestations of adaptive mechanisms that have evolved to satisfy partially incompatible constraints on action control.