Task preparation and stimulus-evoked competition.

The authors investigated how task competition evoked by a stimulus that affords both a currently relevant and a temporarily irrelevant task is affected by invalid preparation, i.e., preparation for the irrelevant task. Although invalid preparation was associated with a general performance cost, effects of stimulus-cued task competition were not enhanced on invalidly prepared trials. This result suggests that either preparation activates representations different from the ones by which stimulus cuing is mediated or that stimulus processing is postponed until invalid preparation has been corrected. In addition, invalid preparation resulted in impaired performance of the respective task when it became relevant on a subsequent trial. This result is consistent with the idea that competition due to invalid preparation is countered by task-specific inhibition.