Interactions between language and inhibitory control: Evidence from a combined language switching and Stroop paradigm

Aims and objectives: This study assessed bilinguals’ language control (LC) and inhibitory control (IC) performance (switch costs and Stroop effects) simultaneously in the same participants to investigate how these processes influence each other. Design: Seventy-four Turkish-English bilinguals were presented with Turkish (L1) or English (L2) color words printed either in congruent or incongruent ink color and instructed to name the ink color of these words in the presentation language. Stimuli’s language and congruency were either the same as in the previous trial or different. Data and analysis: Reaction times (RTs), switch costs (mean RTs on language repetition subtracted from switch trials), and the Stroop effects (mean RTs on congruent subtracted from incongruent trials) were analyzed using the linear mixed-effect model. Findings: The switch costs were larger on incongruent than congruent, and the Stroop effects were larger on language switch than repetition trials. This means that the LC performance decreased while resolving conflict, and the IC performance decreased during switching language, indicating that these two share a common IC mechanism. However, the switch costs and Stroop effects across L1 and L2 were symmetrical in all conditions, leaving the previous interpretation uncertain. Besides, the Stroop effects were larger when followed by congruent than incongruent trials during language repetition, whereas they were equal during switching. This means that the ability to adjust performance by previous experience was disrupted during language switching. Moreover, for the high-L2 proficiency group, this ability was diminished in language repetition trials too. These results indicate that rather than inhibition, other processes may primarily mediate bilinguals’ LC. Originality: This study provides evidence for how language and inhibitory control influence each other by combining language switching and Stroop paradigms. Furthermore, it investigates the sequential congruency effects (SCE). Significance/implications: This study shows that SCE investigation may provide significant theoretical implications.