Inhibition of cued but not executed task sets depends on cue-task compatibility and practice

In task switching, processing a task cue is thought to activate the corresponding task representation ("task set"), thereby allowing for advance task preparation. However, the contribution of preparatory processes to the emergence of n-2 repetition costs as index of task set inhibition processes is debated. The present study investigated whether merely preparing for a task activates a corresponding task set, which needs to be inhibited in order to switch to a different task. To this end, we presented so-called task cue-only trials in trial n-2 and assessed subsequent n-2 repetition costs. The results revealed n-2 repetition costs following a task cue-only, but only for compatible cues with a transparent cue-task relation and only at the beginning of the experiment. In contrast, n-2 repetition costs following task execution in trial n-2 were absent. In a second experiment, we sought to rule out that the presence of n-2 repetition costs following a task cue-only and the corresponding absence following task execution were the consequence of a decay of task sets. This second experiment replicated the result pattern of the first experiment, with n-2 repetition costs following a task cue-only being present only at the beginning of the experiment and only for compatible cues. Hence, cue-induced task set inhibition effects depended on cue-task compatibility and practice. Furthermore, merely prepared task sets were more likely inhibited than executed task sets.