Genetic Evidence for Bidirectional Effects of Early Lexical and Grammatical Development
Référence bibliographique 
Dionne, Ginette, Dale, Philip S., Boivin, Michel et Plomin, Robert. 2003. «Genetic Evidence for Bidirectional Effects of Early Lexical and Grammatical Development ». Child Development, vol. 74, no 23, p. 394-492.
Intentions : « In the present article we explore the overlap of genetic effects, that is, the extent to which genetic influences are shared between vocabulary and grammar at 3 years of age and in longitudinal analyses of change and continuity from 2 to 3 years. » (p. 396)
Échantillon/Matériau : 2 554 same-sex twin pairs from two independent birth cohorts
Instruments : - The MacArthur Communicative Development Inventory (MCDI-Fenson et al., 1994) for the assessment of vocabulary at 2 and 3 years and the assessment of grammar at 2 and 3 years; - The MacArthur Communicative Development Inventory: Words and Sentences (MCDI:WS-Fenson et al., 1994).
Type de traitement des données : Analyse statistique
« This article addresses the autonomy hypothesis of vocabulary and grammar and bootstrapping mechanisms in early language development. Two births cohorts of 1,505 and 1,049 same-sex twin pairs from the UK were assessed at 2 and 3 years on grammar and vocabulary, using adapted versions of the MacArthur Communicative Development Inventory. Vocabulary and grammar correlate strongly at both 2 and 3 years in both cohorts. Multivariate genetic modeling reveals a consistently high correlation between vocabulary and grammar at 2 and 3 years. This finding suggests at the same genetic influences operate for both vocabulary and grammar, a finding incompatible with traditional autonomy hypothesis, at least in early acquisition. Cross-lagged longitudinal genetic models indicate both lexical and syntactical bootstrapping operate from 2 to 3 years. » (p. 394)