Figure 3 shows standardized regression coefficients from the single-trial multiple regression of reaction time (Figure 3A), luminance (Figure 3B), and their interaction (Figure 3C). A robust main effect of reaction time can be seen in the theta range prior to the response, centered around frontal sites. These coefficients were significantly greater than zero in all conditions (Figure 3A), and there was a significant interaction between previous and current conflict (F1,14 = 11.67, p = 0.004), which was driven by significantly larger coefficients in cI compared to cC trials (t14 = 3.48, p = 0.0037), and no significant difference between iI and iC trials (t14 = 1.19, p = 0.187). The relationship between brain activity and RT may reflect conflict and also other response-related processes; however, because basic motoric response-related processes are present during all responses, the difference between regression coefficients in cC and cI trials reflects conflict processing.
