Inhibition Resolves Simon Conflict: Evidence from EEG Decoding

The congruency sequence effect (CSE), a hypothesized marker of top-down cognitive control, refers to a reduced congruency effect after incongruent trials compared to congruent trials. Although this effect has been observed across various distractor interference tasks, the nature of the control processes underlying the CSE remains a topic of active debate. It has been suggested that cognitive control may resolve conflicts in information processing either by (a) enhancing the representation of goal information and/or (b) suppressing the representation of distractor information. The present study aimed to identify the conflict resolution processes within the context of the color Simon task by decoding the goal and distracting information from human scalp EEG signals. For the decoding analysis, models were trained separately for color and location attributes corresponding to goal and distractor information. Additionally, decoding accuracy was calculated in different frequency bands: theta (4-8 Hz), alpha (8-12 Hz), low beta (12-20 Hz), and high beta (20-30 Hz). Results showed that decoding accuracy for distractor information was reduced when cognitive control was activated and this pattern was only observed in the high beta-frequency band (20-30 Hz). In contrast, no such difference was observed for target information. These findings suggest that cognitive control regulates Simon conflict by inhibiting distractor representation in the brain, thereby preventing unwanted distraction-driven behaviors.