The bilingual brain: A comparison of native and non-native speech perception in monolingual and bilingual infants

Abstract

Infants raised in monolingual families are equally good at native and non-native speech discrimination early in life. By 12 months, performance on native speech has significantly improved while non-native performance declines. We tested bilingual American infants at 7 and 11 months of age on native (/ta-pa/) and non-native (Mandarin affricate-fricative) contrasts used in the monolingual tests. Phonetic discrimination was assessed using behavioral (conditioned head-turn) and brain (event-related potential) measures. The MacArthur Communicative Development Inventory estimated infants developing language skills at 14, 18, 24, and 30 months of age. The monolingual data [Kuhl et al., Language Learning and Development (2005)] demonstrated that at 7 months of age, infants native and non-native speech perception skills predicted their later language development, but differentially. Better native phonetic perception predicted more rapid language development between 14 and 30 months, whereas better non-native phonetic perception predicted slower language development over the same time period. Performance of bilingual infants on the same speech perception tasks, and their patterns of language growth between 14 and 30 months, will be compared to those of the monolingual infants, and a model that accounts for the results will be described. [Work supported by NSF, NIH, and the Human Frontiers Science Program.]