The role of temporal cue-target overlap in backward inhibition under task switching

One of the proposed mechanisms for sequential control in task-shift conditions is backward inhibition (BI), which is usually measured in terms of lag-2 task repetition costs in A-B-A task sequences relative to C-B-A task sequences. By considering the so far existing experiments it seems that these lag-2 repetition costs occur only with temporally overlapping cues and targets. In the present study this issue was further examined in two experiments, in which temporal cue-target overlap was varied blockwise (Experiment 1) and from trial-to-trial (Experiment 2). Experiment 1 shows that lag-2 repetition effects can only be observed with temporally overlapping cues and targets, indicating that there was no BI with temporally separated cues and targets. However, the results of Experiment 2 suggest that both irrelevant task sets are inhibited in this case, and that with temporally overlapping cues and targets only the previously relevant task set is inhibited.