Language discrimination in monolingual and bilingual infants of Spanish and Basque

Molnar, M. 1 , Gervain, J. 2, 3 , Peña, M. 4 , Baart, M. 1 , Quiñones, I. 1 & Carreiras, M. 1

1 Basque Center on Cognition, Brain and Language (BCBL). Donostia. Spain
2 CNRS, Paris, France
3 Université Paris Descartes, Sobornne Paris Cité, Paris, France
4 Catholic University of Chile, Santiago, Chile

It has been established that newborns use rhythmical properties as a cue for discriminating between languages they have never heard before (e.g., Ramus, 2002), and 4-5-month-old monolingual infants are able to distinguish their own native (or familiar) language from an unfamiliar (non-native) one even if they belong to the same rhythmical class (e.g., Nazzi et al., 2000). However, for bilingual infants both languages are familiar, and potentially from the same rhythm class; therefore, bilingual infants might develop strategies different from those of their monolingual peers to succeed in language separation. Limited studies on bilingual infants? discrimination have shown that newborns discriminate two rhythmically dissimilar native languages, while recognizing both languages as familiar (Byers-Heinlein et al., 2010). Also, bilingual infants at 4 months are adept at recognizing and discriminating their two native and rhythmically similar languages (e.g., Bosch and Sebastian-Galles, 1997;2001.) Although, based on what cues bilingual infants distinguish their rhythmically similar native languages is unclear. In order to investigate what cues might be crucial to guide bilingual infants toward the development of language separation, we carried out a set of infant and adult perceptual experiments, in addition to the acoustic analysis of Spanish and Basque. Language discrimination of Spanish-Basque monolingual and bilingual infants at 3.5 months of age were measured in a set of behavioral (visual habituation) and NIRS (Near-infrared spectroscopy) experiments in response to Japanese vs. Polish (unfamiliar and rhythmically different languages), and Spanish vs. Basque (familiar and rhythmically similar languages). Our overall results suggest that bilingual infants are able to separate their rhythmically similar native languages even before 4 months of age, most likely by relying on differences in vocalic distributions as a cue across the two inputs.