Electrophysiological correlates of task conflicts in task-switching

The current study investigated how stimulus -induced task conflicts influence task-switching, and how this effect modulates the post-stimulus switch-related event-related potentials (ERPs). In most task-switching paradigms, the stimulus display comprises a target and a distractor, which together can cause task conflicts when each is associated with a different task-set. To avoid performance interference due to task conflicts, it may be necessary to suppress inappropriately activated responses afforded by the irrelevant stimulus (Stimulus-Response (S-R) inhibition), or the entire irrelevant task-set (task-set inhibition) in response to contextual changes. The current study employed a pair-wise task-switching paradigm, in which task-switching and repeat trials were compared among three stimulus conditions-neutral, congruent, and incongruent-to distinguish the two types of inhibition. The results of the current study showed that both mean response time (RT) and the P3b effect were modulated by the stimulus condition, and reliably differed in both the congruent and incongruent stimulus conditions from the neutral stimulus conditions. Thus, the electrophysiological results of the current study suggest that the P3b component involves inhibitory processes to overcome stimulus -induced task conflicts at the level of the entire irrelevant task-set in task-switching. (c) 2008 Elsevier B.V. All rights reserved.