Is There an Effect of Diglossia on Executive Functions? An Investigation among Adult Diglossic Speakers of Arabic

Recent studies investigating whether bilingualism has effects on cognitive abilities beyond language have produced mixed results, with evidence from young adults typically showing no effects. These inconclusive patterns have been attributed to many uncontrolled factors, including linguistic similarity and the conversational contexts the bilinguals find themselves in, including the opportunities they get to switch between their languages. In this study, we focus on the effects on cognition of diglossia, a linguistic situation where two varieties of the same language are spoken in different and clearly separable contexts. We used linear mixed models to compare 32 Arabic diglossic young adults and 38 English monolinguals on cognitive tasks assessing the executive function domains of inhibition, and switching. Results revealed that, despite both groups performing as expected on all tasks, there were no effects of diglossia in any of these domains. These results are discussed in relation to the Adaptive Control Hypothesis. We propose that any effects on executive functions that could be attributed to the use of more than one language or language variety may not be readily expected in contexts with limited opportunities for switching between them, especially in younger adults.