The Congruency Sequence Effect Is Modulated by the Similarity of Conflicts

The congruence effect can be modulated by adjacent conflict conditions, producing the congruency sequence effect (CSE). However, many boundary conditions prevent the transfer of the cross-conflict CSE. A consensus has been achieved that the CSE reflects both top-down control and bottom-up associative learning, but neither perspective could perfectly interpret the various boundary conditions. Their imperfections recently inspired an integrative learning account of cognitive control, which predicts that conflict similarity affects the magnitude of the cross-conflict CSE. We examined this hypothesis with the spatial Stroop-Simon paradigm by introducing a compound condition containing both the Stroop and Simon components (Experiment 1). The conflict similarity was defined by the degree of component overlap, as manipulated by the polar angle of the target arrow in Experiments 2a and 2b and by the Euclidean distance of the target arrow in Experiments 3a and 3b. Mixed-effect modeling analyses indicated that, in all experiments, the cross-conflict CSEs were positively correlated with the similarity among conflict conditions. Specifically, the compound condition with equal Stroop and Simon components generated comparable CSEs with both the Stroop and Simon conditions (Experiment 1). When the compound condition was more similar to the Stroop than the Simon condition, a trend of a larger CSE was observed between the compound conflict and the Stroop condition than between the compound conflict and the Simon condition, and vice versa (Experiments 2 and 3). Our study revealed that the continuum of the cross-conflict CSE was modulated by conflict similarity, hence supporting the integrative learning account of cognitive control.