Can contingency learning alone account for item-specific control? Evidence from within- and between-language ISPC effects.

The item-specific proportion congruence (ISPC) manipulation (Jacoby, Lindsay, & Hessels, 2003) produces larger Stroop interference for mostly congruent items than mostly incongruent items. This effect has been attributed to dynamic control over word-reading processes. However, proportion congruence of an item in the ISPC manipulation is completely confounded with response contingency, suggesting the alternative hypothesis, that the ISPC effect is a result of learning response contingencies (Schmidt & Besner, 2008). The current study asks whether the ISPC effect can be explained by a pure stimulus-response contingency-learning account, or whether other control processes play a role as well, by comparing within- and between-language conditions in a bilingual task. Experiment 1 showed that contingency learning for noncolor words was larger for the within-language than the between-language condition. Experiment 2 revealed significant ISPC effects for both within- and between-language conditions; importantly, the effect was larger in the former. The results of the contingency analyses for Experiment 2 were parallel to that of Experiment 1 and did not show an interaction between contingency and congruency. Put together, these sets of results support the view that contingency-learning processes dominate color-word ISPC effects.