Investigation of language and interference control in bilinguals through a combined stroop and language switching task

Previous studies have demonstrated that bilinguals perform better in executive function tasks compared to monolinguals. Other studies have demonstrated that even in contexts that require using only one language, both languages of a bilingual are simultaneously active. This suggests that bilinguals should apply some sort of control to the non-target language. Since the control of the non-target language is mainly through the general executive control functions, the experience and practice of language control lead to a better performance in executive functions. In order to examine whether the language and executive control share the same control mechanisms, we designed a Combined Stroop and Language Switching task where the measures for language control (language switching cost) and interference control (Stroop effect) were obtained simultaneously and we manipulated the language switching context. At first, we investigated the validity of the Combined Stroop and Language Switching task. The results demonstrated that this task can be used as a valid measuring tool. Afterwards, we investigated the measures for language switching cost and Stroop effect obtained from the task. The results demonstrated that both language switching cost and Stroop effect performance were lower in the context with high language control demands, compared to context with low language control demands. Moreover, the language switching cost performance was lower in incompatible compared to compatible trials, and similarly, the Stroop effect performance was lower in language switch compared to language repetition trials. Considering that similar results were obtained for both measures, we concluded that the performance related to language and interference control share the same control mechanisms. The results of this study are discussed within the framework of Inhibitory Control Model (Green, 1998), The Adaptive Control Hypothesis (Green & Abutalebi, 2013) and Conflict Monitoring Theory (Botvinick, 1999).