Temporal dynamics of conflict adaptation across different conflict strengths.

Conflict adaptation is considered to reflect the adjustment of cognitive control, and it is critical for adaptive behavior. Despite intensive investigations on conflict adaptation, straightforward evidence on how changes in conflict strength influence the behavioral and neural dynamics of conflict adaptation remains scarce. To address this issue, we manipulated conflict strength by varying distractor-target congruency to investigate whether conflict strength per se or the expectancy of conflict strength triggers the adjustment of cognitive control. Behavioral and electroencephalographic (EEG) measures were recorded while participants performed a variant four-choice flanker task without feature repetitions. The behavioral results showed that reaction times increased with increasing conflict strength. Importantly, there were conflict adaptations between the congruent and incongruent-low, congruent and incongruent-high, and incongruent-low and incongruent-high conditions. Consistent with the behavioral results, the EEG results revealed that N2 and P3 were sensitive to conflict strength. Critically, there were typical conflict adaptations between every two conflict conditions on the early P3 amplitude related to the adjustment of attentional strategies. However, there were no differences among these conflict adaptation effects, both on reaction times and the early P3 amplitude, demonstrating that the expectancy of conflict strength rather than conflict strength per se may play a crucial role in conflict adaptation. Altogether, these results emphasize the functional role of expectancy based on previous conflict strength in the exertion of cognitive control, which is in accordance with the repetition expectation theory than with the conflict monitoring theory.