Adjustments to recent and frequent conflict reflect two distinguishable mechanisms.

In conflict paradigms such as the Eriksen flanker task, interference has been found to be reduced under conditions of recent and/or frequent cognitive conflict. Using a modified flanker task, we investigated the interplay of conflict recency and conflict frequency by comparing the interference reductions following conflict trials under conditions in which conflict was either frequent or infrequent overall, while controlling for stimulus and response feature repetitions to rule out nonattentional accounts. The reduction of flanker interference after a conflict trial was attenuated when overall conflict was frequent. This result is consistent with models assuming that processing adjustments occur gradually in response to conflict strength, such as the connectionist model of Botvinick, Braver, Barch, Carter, and Cohen (2001), in which both recency and frequency modulations are brought about by the same mechanism. By decomposing response times into initiation times and movement times, we revealed that frequent conflict delayed response initiation but sped up movement. Moreover, whereas frequent conflict reduced interference in both components, interference reduction after individual conflict trials was confined to movement times. Taken together, these results suggest that different mechanisms underlie the two kinds of modulation.