ABSTRACT
Congruency effects observed in stimulus-response compatibility paradigms are affected by proportion congruency (PC), that is, the ratio of congruent trials in a block-wise context. The PC effect may reflect the operation of visual selectivity. We used a flanker task to investigate the nature of the relationship between the congruency effect and PC in a given block, as well as the preservation of visual selectivity. In Experiment 1, we observed a linear relationship between the congruency effect and PC across five PC groups in a training session; in post training (with PC constant), the congruency effect was equivalent across the five groups. In Experiment 2, congruency effects varied with PC in phases within a block. These suggest that visual selectivity, acquired in a training session, is not sustained in post training where it rapidly adjusts to a new PC context. Characteristics of visual selectivity derived from these findings are discussed.