Bilingual Lexical Acquisition. On the crossroads of early word production and grammar: Evidence from a French-Russian bilingual child aged from 2;0 to 4;0

International audienceRecent studies on bilingual children's word learning have shown a strong correlation between input environment in each language and the child's actual lexical production (Patterson, 2002; Marchman et al., 2004). Thus, unbalanced input may result in the unbalanced proficiency (Schlyter, 1995; Döpke, 1998; Serratrice, 2005; Jisa, 2000; Comeau et al., 2007). Inspite of the general assumption that the bilingual vocabulary size is smoller, young bilinguals and monolinguals develop languages in similar way (De Houwer, 2009).Our study focuses on the bilingual child's lexical development growing up with two languages from birth (French and Russian). We attempt to clarify whether the acquisition of two distinct linguistic systems has an impact on the emerging relationships between vocabulary size and grammar development, as well as the input frequency role. The analysed corpus consists of a twenty-eight-hour transcribed data collected during dyadic 'parent - child' conversations for a two-year period.Our findings have shown a strong link between vocabulary size and morphosyntactic development and support the "critical mass" hypothesis in both languages. According to this hypothesis, the emergence of noun and verb morphology results in quantitative shift of vocabulary only after the size of the lexicon attains a certain level (Plunkett & Marchman, 1993; Marchman & Bates, 1994; Bassano, 2005). The data gathered in this study show a clear evidence that the grammatical-category emergence in both languages takes place within a two-month period after the spurt of lexical categories alike in monolingual French-acquiring children (Bassano, 2005). Our data also strongly suggest a clear correlation between input frequency and the child’s linguistic competence in both languages: the acquisition of French follows developmental paths of French monolingual children, while Russian is acquired with a substantial time delay. These findings contribute to the understanding of the developmental complexity that underlines early lexical acquisition of two distinct languages