The effect of bilingual exposure versus language impairment on nonword repetition and sentence imitation scores

Purpose: Nonword repetition (NWR) and sentence imitation (SI) are increasingly used as diagnostic tools for the identification of Primary Language Impairment (PLI). They may be particularly promising diagnostic tools for bilingual children if performance on them is not highly affected by bilingual exposure. Two studies were conducted which examined (1) the effect of amount of bilingual exposure on performance on French and English nonword repetition and sentence imitation in 5-year-old French-English bilingual children and (2) the diagnostic accuracy of the French versions of these measures and of receptive vocabulary in 5-year-old monolingual French-speakers and bilingual speakers with and without PLI, carefully matched on language exposure. Method: Study 1 included 84 5-year-olds acquiring French and English simultaneously, differing in their amount of exposure to the two languages but equated on age, nonverbal cognition and socio-economic status. Children were administered French and English tests of NWR and SI. In Study 2, monolingual and bilingual children with and without PLI (four groups, n = 14 per group) were assessed for NWR, SI, and receptive vocabulary in French to determine diagnostic accuracy. Results: Study 1: Both processing measures, but in particular NWR, were less affected by previous exposure than vocabulary measures. Bilingual children with varying levels of exposure were unaffected by the length of nonwords. Study 2: In contrast to receptive vocabulary, NWR and SI correctly distinguished children with PLI from children with typical development (TD) regardless of bilingualism. Sensitivity levels were acceptable, but specificity was lower. Conclusions: Bilingual children perform differently than children with PLI on NWR and SI. In contrast to children with PLI, bilingual children with a large range of previous exposure levels achieve high NWR scores and are unaffected by the length of the nonwords. Learning outcomes: Readers will recognize the effect of language input on the rate of language development, focusing specifically on how bilingual exposure affects the language learning of each language of bilingual children. (c) 2012 Elsevier Inc. All rights reserved.