Development of biliteracy in bilingual children: effects on language and cognition

The present thesis provides a comprehensive assessment of Greek-English bilingual children’s language and literacy skills in both languages as well as their cognitive abilities. Moreover, patterns of predictors of word reading and reading comprehension are compared between monolinguals and bilinguals, and across the two languages. Different indices of biliteracy were calculated to assess their predictive validity with regard to oral language and executive function skills. Results showed clear bilingual profile effects which were more pronounced in the minority language Greek. Vocabulary was found to be the greatest challenge for bilinguals, and the results showed that vocabulary affected performance on most other oral language and literacy measures. Notably, the bilingual children performed on a par with the monolinguals in measures of basic literacy skills in the majority language English, and only showed a small gap in reading comprehension. The analyses further showed that the pattern of predictors of reading performance was highly similar across groups and languages. However, differences emerged in the relative contributions of the underlying skills in that verbal WM was a better predictor of word reading in the bilinguals, while RAN was a better predictor in the two monolingual groups. Thus, the findings point to the possibility that the bilingual children are able to compensate for their lower vocabulary skills by relying more on their verbal working memory to perform at monolingual levels on basic literacy measures in the majority language. In addition, there was evidence that biliteracy is associated with better performance on tasks tapping working memory and updating, while there was no indication of positive effects of biliteracy on oral language skills in either language. Taken together, the results underscore the pivotal role of vocabulary for performance on oral language and literacy measures, and point to the benefits of developing literacy in the minority language