Fast responders have blinders on: ERP correlates of response inhibition in competition.

Recent studies have demonstrated that individuals acting in a social context form shared representations, resulting in incorporating another person's action plan into their own. The present study investigated the extent to which shared representations are formed in a competitive task. Specifically, it was tested whether in competition the process of response inhibition is affected by explicit knowledge of another's task. Event-related potential (ERP) correlates of response inhibition were measured while pairs of participants competed with each other on a speeded go/no-go task. Participants were instructed to always try to respond faster than their direct competitor. No-go stimuli requiring an inhibitory response of the other person as well (compatible action) or no-go stimuli to which the other person should respond (incompatible action) were directly compared. Behavioral performance measures and response inhibition, as reflected in the no-go P3, were decreased on incompatible actions compared to compatible ones. Interestingly, both the behavioral and the ERP effects were caused by the slow responding and thus unsuccessful competitors. These findings indicate that shared representations are formed in competitive tasks, but differently for successful and unsuccessful competitors. Only the slow responders are impeded by incompatible actions. The present study therefore demonstrates that the formation of shared representations is not a fully automatic process. People can differ in the extent to which they incorporate the other's action plan into their own and this may be closely related to successful performance in competitive action.