Congruency precues moderate item-specific proportion congruency effects

The item-specific proportion congruency (ISPC) effect refers to the reduction in the Stroop effect for items (e.g., words) that mostly appear in an incongruent format, as compared to items that mostly appear in a congruent format. It is thought to demonstrate reactive control of word-reading processes. In the present study, we tested the hypothesis that using explicit, trial-by-trial congruency precues to proactively guide attention during a color-word Stroop task could reduce the otherwise robust ISPC effect. In Experiment 1, the precueing manipulation was employed alongside a manipulation traditionally thought to influence proactive control of word-reading processes (i.e., list proportion congruence [list PC]). Precueing participants with 100 %-valid precues eliminated both the ISPC effect and the list PC effect. In Experiment 2, we used 70 %-valid congruency precues to direct participants to generally expect conflict or congruence on a given trial. ISPC effects were selectively reduced when the participants expected conflict. These results suggest that precueing influences engagement in proactive control and, as a result, reduces the impact of item-specific and list-based tendencies to direct attention toward or away from word reading.