Rhythmic distance between languages affects the development of speech perception in bilingual infants

The time course and trajectory of development of phonetic perception in Spanish-Catalan bilingual and monolingual infants is different (Bosch & Sebastián-Gallés, 2003a, 2003b, 2005; Sebastián-Gallés & Bosch, 2009). Bosch & Sebastián-Gallés argue that, at least initially, bilingual infants track statistical regularities across the two languages, leading to their temporary inability to discriminate acoustically-similar phonetic categories. In this paper, we test bilingual Spanish-English 4and 8-month-olds’ discrimination of vowels. Results indicate that, when the two languages being learned are rhythmically dissimilar, bilingual infants are able to discriminate vowel contrasts that are phonemic in one, but not the other language, at an earlier age. These results substantiate a mechanism of language tagging or sorting; such a mechanism is likely to help bilingual infants calculate segmental statistics separately for the two languages.