[Stimulus set and response set in task switching: a comparison using ERP]

Event-related potential (ERP) and reaction time (RT) were recorded to investigate the time course of processes involved in set switching. The cued set-switching paradigm required participants to switch stimulus task sets between male and female face-images memorized as targets prior to a trial block and response task sets between two stimulus-response mappings for each stimulus task. Replicating previous findings, an RT switch-cost was found when compared with set-repeat trials. The RT was also prolonged for a stimulus task requirement of memory comparison with two-face targets rather than one face. A similar prolongation with memory comparison was observed in P3b latency, which showed no switch effect. The switch effect was observed for the onset latency of stimulus-locked lateralized readiness potential (LRP), measured as an index of commencement of motor processes after response selection. The response-locked LRP indicated that the final process of motor execution itself was not modified by set switching. The processes producing the stimulus-locked LRP switch cost, associated with response task set, were discussed in terms of two hypotheses, exogenous reconfiguration and carryover.