Lexical Competition between Spoken and Literary Arabic: A New Look into the Neural Basis of Diglossia Using fMRI

Diglossia in the Arabic language refers to the socio-linguistic situation in which Spoken Arabic (SA), which is the first to be acquired, is used for everyday communications, while Literary Arabic (LA), acquired at school for reading and writing, is also used for formal functions. Although some authors consider SA and LA as a first and second language, the question of how these are managed in the brain has not yet been understood. Using functional magnetic resonance brain imaging (fMRI) analysis, this study aimed at exploring the neural basis of diglossia during picture naming in two contexts. In the first, healthy young participants were instructed to name each image either in SA or LA on the basis of cue word appearing after the stimulus. In the second, they were instructed to name images either in SA or in Hebrew. Behavioral analysis showed that naming in SA was slightly easier than LA and considerably easier than Hebrew. fMRI analysis showed no difference between SA and LA. Hebrew compared to SA revealed activation differences explainable in terms of engagement of language control modules and second- to first-language effects. These findings, discussed in the light of previous findings in bilingual literature, support the view that dominance in diglossia is modality-dependent.