Language change in bilingual returnee children: mutual effects of bilingual experience and cognition

Abstract

In this thesis, I focus on the linguistic changes that occur within bilingual returnee children; that is, children who were immersed in a second language (L2) dominant environment and returned to their first language (L1) environment. Tracking the development of such a specific population allows us to disentangle the effects of age from those of the bilingual experience. Longitudinally, these returnee children (ages 7-13) experience an increase in age but decrease in L2 exposure. In other situations that have been studied, age and bilingual experience are variables that are often difficult to tease apart because they are positively correlated. As this is not the case for the population I study, longitudinal data from bilingual returnee children offer opportunities to separate the relative influence of these factors on children’s language and cognitive development. Linguistic changes that occur due to detachment from the L2 environment are typically defined as ‘L2 attrition’. However, these linguistic changes do not necessarily entail a loss of the second language and can be manifested through various linguistic phenomena. Thus, the first aim of the thesis is to examine what aspects of the language undergo changes over time. Various structures of the language, both in L1 and L2 are examined—from genitive structures (Chapter 6) to lexical access (Chapter 7) and language control (Chapter 8). The results of these studies demonstrate that not all changes in L2 are recessive (Chapter 7 and 8) and not all linguistic structures are vulnerable to change (Chapter 6). Specifically, the results of Chapter 6 show that cross-linguistic transfer alone cannot explain the change in preference for linguistic expressions, and instead suggest that processing difficulties (i.e., effects of bilingualism per se) are also at play in the selectivity of language change. The second aim of the thesis is to examine what factors contribute to the process of language change in returnee children. Chapter 7 specifically examines the role of individual variables such as age of L2 onset, length of residence, language exposure, and proficiency on the changes in lexical access. The finding is that length of residence plays a crucial role in L2 maintenance, supporting the maturational account that children require some time to stabilize their language knowledge so that it becomes resistant to change. In addition to individual variables, Chapter 8 explores the influence of cognitive factors on language control. Given the intricate relationship between bilingualism and cognition, I hypothesized that children who are better ‘developers’ in general cognition may also be better ‘retainers’ of the language. The findings offer support for this hypothesis—children who improved their cognitive performance (measured by the Simon task) also better developed their language control (measured by the language-switching paradigm), especially in their L2. Chapter 9 then focuses on the change in general cognition rather than in language, by demonstrating that proficiency is a significant determinant for development in executive control— children who had higher L2 proficiency showed a more significant enhancement in their cognitive performance over time. Through these studies, this thesis contributes to an understanding of attrition and cognition in the development of children. Although much more work is required to fully explore the interplay of factors, this thesis provides evidence that executive control, in addition to bilingual experience, may affect (and even offset) the effects of language attrition in bilingual children.