Instruction effects in task switching.

The present study examined the effect of instructions on sequential task preparation using a cuing paradigm with three tasks. All task transitions were predictable, whereas task identity was unpredictable in switches but predictable in repetitions. In Experiment 1, predictability (predictable vs. random) was manipulated while preparation time (i.e., the cue-stimulus interval, or CSI) remained constantly short. In Experiment 2, CSI was manipulated for predictable task transitions. Both experiments showed clear instruction effects, but these were restricted to predictable task repetitions, for which predictability determined the identity of the upcoming task. Predictability effects were small in task switches and were not modulated by instruction, suggesting that preparation is mainly task-specific rather than switch-specific. Together, these results suggest that intentional processes contribute to predictability benefits in task repetitions, probably by enhancing the monitoring of sequential transitions in working memory in order to maintain activation in task repetitions.