Congruency sequence effects and cognitive control.

Congruency effects in selective attention tasks are subject to sequential modulation: They are smaller following an incongruent stimulus than following a congruent one. This congruency sequence effect has been interpreted as reflecting conflict-driven adjustments in cognitive control (conflict adaptation) or, alternatively, episodic memory effects of stimulus-response association (feature integration). The present article critically reviews support for these rival accounts in the experimental literature and discusses the implications thereof for assessing behavioral and neural signatures of cognitive control processes. It is argued that both conflict adaptation and feature integration contribute to the congruency sequence effect but that their respective contributions can be isolated experimentally. Studies that have pursued this isolation strategy have gained important insights into cognitive control processes. Finally, other factors, such as expectancies, may also contribute to the congruency sequence effect, and thus their potential role needs to be carefully examined and, if found significant, integrated into current models of cognitive control.