Decoding the dynamics of cognitive control: Insights from reach movements and electroencephalography

The congruency sequence effect (CSE) refers to improved performance in conflict tasks, such as the Eriksen flanker task, when the congruency of the current trial matches that of the preceding one. Although widely attributed to dynamic adjustments in cognitive control, the neural mechanisms and temporal dynamics underlying this effect remain poorly understood. Here, we combined a release-and-press flanker task with EEG decoding to examine how trial congruency and response type shape behavior and brain activity in healthy adults. Behaviorally, the CSE emerged only when responses repeated, highlighting the dominant role of stimulus-response binding over abstract control mechanisms. Neural decoding mirrored the CSE: current-trial congruency was more reliably decoded on repeated-response trials following congruent versus incongruent trials. This neural CSE was stimulus-locked, occurred between 450-550ms post-stimulus onset, and was driven by theta-band activity. More broadly, congruency decoding was particularly robust over frontal channels while cross-temporal generalization indicated transient, sequential neural representations underlying control signals. Together, these findings demonstrate that both behavioral and neural signatures of the CSE are tightly constrained by response repetition and emerge within a narrow temporal window. By integrating reach-based measures with multivariate EEG analyses, this study provides a fine-grained account of when, where, and under what conditions control-related signals unfold after conflict.