Spatial congruence in working memory: an ERP study.

The Simon effect refers to the finding that reaction times are faster when stimulus and response locations are congruent than when they are not, even stimulus locations are task irrelevant. Zhang and Johnson reported a Simon-like spatial congruence effect in working memory. This study examined the neural mechanisms of this memory-based spatial congruence effect by recording event-related potentials to probe stimuli. Behavioral results showed a clear congruence effect. The P300 amplitudes were larger in the congruent condition than in the incongruent condition. The results suggest that the memory-based congruence effect and the classical Simon effect were mediated by similar neural mechanisms and support theories assigning response selection an essential role in spatial congruence effects.