Cross-linguistic transfer in bilinguals reading in two alphabetic orthographies: The grain size accommodation hypothesis.

Reading acquisition is one of the most complex and demanding learning processes faced by children in their first years of schooling. If reading acquisition is challenging in one language, how is it when reading is acquired simultaneously in two languages? What is the impact of bilingualism on the development of literacy? We review behavioral and neuroimaging evidence from alphabetic writing systems suggesting that early bilingualism modulates reading development. Particularly, we show that cross-linguistic variations and cross-linguistic transfer affect bilingual reading strategies as well as their cognitive underpinnings. We stress the fact that the impact of bilingualism on literacy acquisition depends on the specific combination of languages learned and does not manifest itself similarly across bilingual populations. We argue that these differences can be explained by variations due to orthographic depth in the grain sizes used to perform reading and reading-related tasks. Overall, we propose novel hypotheses to shed light on the behavioral and neural variability observed in reading skills among bilinguals.