Liu, L. & Kager, R.
Utrecht Insititute of Linguistics - OTS, Utrecht University
It remains unclear whether mono- and bilingual infants follow the same developmental trajectory in early language acquisition. Two patterns were reported regarding early bilingual vowel perception: first, bilingual infants keep the same pace as their monolingual peers (Albareda-Castellot et al., 2011; Sundara & Scutellaro, 2010), and second, temporary delay occurs in the first year of life, leading to a U-shaped perceptual pattern (Bosch & Sebastián-Gallés, 2003a, Sebastián-Gallés & Bosch, 2009). The potential influential factors for the latter pattern are argued to be cross-language statistical regularities / relative frequencies, overlapping vowel categories in the perceptual space, rhythmic similarity between the target languages, parents' language mixing etc. The current study asks whether monolingual and bilingual infants follow the same developmental trajectory in vowel perception. 200 monolingual Dutch and 104 bilingual infants with Dutch as one L1 aged 5-6, 8-9, 11-12 and 14-15 months were tested on their perception of the Dutch /i-I/ vowel contrast, in which the major acoustic difference resides in spectrum but not duration, via a visual habituation procedure. Results show that neither mono- or bilingual infants discriminate the contrast at 5-6 months. Dutch infants discriminate the contrast at around 11-12 months (p < .001), whereas bilingual infants show discrimination 3 months earlier, at 8-9 months (p = .007). The initial failure of native contrast discrimination reveals the relative acoustic difficulty of the Dutch /i-I/ vowel contrast. A similar case was previously found for a less-salient native consonant contrast (Tagalog /na/-/?a/, Narayan et al., 2010). The new finding that bilingual infants are ahead of monolinguals in discriminating a native contrast may be caused by bilingual infants' complex language environment. In addition, thresholds of absolute and/or relative frequency in the bilingual input may exist in order for infants to command native phonetic categories.