Task-Specific Modulation of Cognitive Control: Electrophysiological Evidence From Bivalency Effect in Task Switching.

An occasional presence of bivalent stimuli in a block of univalent trials can elicit a slowing of the response on all subsequent univalent trials. This type of modulation of cognitive control is termed the bivalency effect. To explore whether this modulation is task specific, this study used a triplet task switching paradigm, with three following tasks that were presented concussively: a shape color judgment (red vs. blue), a number parity judgment (odd vs. even), and a letter case judgment (lowercase vs. uppercase). The event-related potential (ERP) results showed that (1) the bivalency effect was reflected by the decreased amplitude of N2 and P3a over the frontal region for both the color and letter tasks; (2) the bivalency effect occurred earlier for the color task compared with that for the letter task; (3) for the number parity task, the bivalency effect was observed in the increased N1 and the decreased P2p over the parietal region. These findings indicate that the modulation of cognitive control is task-specific after the presentation of bivalent stimuli in task switching.