反応準備段階における競合処理と競合適応効果の関連

Performance in the stimulus-response compatibility task is affected by the compatibility in a previous trial. This conflict adaptation effect was explained by the conflict monitoring theory (Botvinick et al., 2001). Reaction time in an incompatible trial is reduced by cognitive control elicited by conflict processing in the previous trial. It is important feature of the theory that the monitoring system detect conflict at response level. To investigate whether conflict in the response preparation process would predict the amount of conflict adaptation effect, I recorded the lateralized readiness potential (LRP), and tested the relationship between its amplitude and latency and the conflict adaptation effect in the Strop task. In addition, because it was reported by recent research (Braem et al., 2012) that conflict adaptation effect correlates reward sensitivity, this study aims to reproduce that correlations. Results showed that no conflict adaptation effect was found in response time. The amount of conflict adaptation had a positive correlation with individual reward sensitivity, especially the Fun-Seeking factor, measured by the Behavioral Action System Drive scale. LRP onset latencies were not longer for incompatible trials than for compatible trials. In addition, mean amplitude of stimulus locked LRPs had no difference due to compatibilities, and did not correlate with the amount of conflict adaptation. Thus, this study did not show conflict adaptation effect nor the effect of compatibility in all index of LRPs. Future experiments are necessary using other cognitive tasks which could arise robust conflict adaptation effect in reaction time. As for second aim of this study, correlation between conflict adaptation effect and individual reward sensitivity was reconfirmed. It suggests that the biological reward system is involved in the conflict monitoring system.