Event-related lateralized readiness potential correlates of the emotion-priming Simon effect

The Simon effect indicates that the reaction time (RT) is shorter when the stimulus and response locations are congruent than when they are not. This study used a priming-target paradigm to explore the emotion-priming Simon effect with event-related potential techniques. The technique of residue iteration decomposition was employed to analyze the lateralized readiness potential (LRP) component, which contributed to disentangling the overlap between LRP and N2 central contralateral in the Simon task with horizontal stimulus-response arrangements. The behavioral result revealed significant Simon effect in RT. In the neural process, the Simon effect was reflected by both the stimulus-locked LRP (S-LRP) and the response-locked LRP (R-LRP), with the incongruent condition showing longer onset latency, larger Gratton-dip, and smaller negative-going deflection of S-LRP and smaller negative-going deflection of R-LRP. These findings suggest that the interference of irrelevant location information is located at the perceptual-encoding (indicated by S-LRP) and response-execution stages (indicated by R-LRP), providing evidence for both the perceptual-interference and response-interference accounts. However, the further linear regression result signaled that the Simon effect might be more closely related to the response-execution stage than the perceptual-encoding stage. In addition, the influence of emotion on the Simon effect was salient only in the incongruent condition, showing longer onset latency of S-LRP and larger Gratton-dip of R-LRP in the negative emotion-priming condition than in the neutral emotion-priming condition, which revealed that the emotional interference effect arose from the stages of perceptual encoding and early response execution only when the locations of a stimulus and the corresponding response were incongruent.