Calendrier

Despite the importance of bilingualism in the world and in France (Simon & Beauchemin, 2010), research on language development in simultaneous bilingual children at an early age is rare and lacks consensus.

This dissertation analyzes the lexical development of thirty French-European Portuguese (EP) bilingual children living in France and Switzerland, aged between 16 and 35 months. Their skills were assessed both cross-sectionally and longitudinally. Lexical development was measured through parental reports using the French Communicative Development Inventory (IFDC 16-30; Kern & Gayraud, 2010) in French and the European Portuguese MacArthur–Bates Communicative Development Inventories (EP-CDI; Viana et al., 2017) in EP. To assess phonological production and memory in each language, the children completed tasks involving picture naming, word repetition, and nonword repetition. The Parent Questionnaire for Bilingual Children (PaBiQ) was used to measure language dominance, and the ASQ-3 was used to assess general developmental levels. Additionally, spontaneous 60-minute interactions between the children and their relatives were recorded at home, then transcribed and analyzed to complement the questionnaire data. Overall, each child was filmed for an average of 90 minutes.

First, the dissertation focuses on bilingual lexical acquisition, comparing vocabulary size of bilingual children with that of monolinguals. The results indicate that bilinguals have a larger total vocabulary size (TV), but a similar conceptual vocabulary (CV) size compared to monolinguals (Thordardottir et al., 2006). A strong exposure to a language is correlated with a larger vocabulary size in that language, confirming the importance of language exposure (Hoff & Naigles, 2002).

Next, it examines the relationship between phonological memory and lexical development, showing that phonological memory is strongly associated with vocabulary size and performance in naming tasks (Chiat & Roy, 2008; Gathercole et al., 1997). The experimental tools developed reveal a strong connection between phonological skills and lexical development (Sharp & Gathercole, 2013).

Finally, it explores the relationship between executive functions, such as working memory and inhibition, and lexical development in bilingual children aged 24-25 and 30-35 months. The results reveal significant positive correlations between working memory and inhibition skills; however, they show only a tendency toward correlation between these cognitive functions and lexical development in younger children (Duncan et al., 2008; Stokes & Klee, 2009), suggesting a potential ceiling effect in cognitive measures and an increased complexity of relationships as children grow.

In conclusion, this dissertation offers a detailed analysis of bilingual development, highlighting the importance of early and continuous language exposure and the need for adapted assessment tools. The results demonstrate the complexity of the interactions between lexical, phonological, and cognitive development, providing a solid foundation for future research and for improving support for bilingual children in various educational and clinical settings.

Keywords: bilingualism, lexical acquisition, lexical development, phonological development, cognitive development, parental questionnaires