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Abstract

An important predictor of early language development is the ability to recognize words from continuous speech. This is a non-trivial task even for infants exposed to only one language. Infants learning trochaic languages use the statistical regularities of the stress patterns of their native language to facilitate word segmentation. Here, we examine the effects of learning one or two trochaic languages, English and/or Welsh, which differ in the salience of the first syllable on ERP indices of word segmentation. Although both languages are stress-based, the difference between stressed and unstressed syllables is more salient in English. Welsh typically has a short first vowel and a lengthened second syllable, providing a syllable-based cue, and initial stress is a less reliable predictor of word onset. In the present study, 32 10-month-olds exposed to only English or both English and Welsh participated in the study. Infants were familiarized to 4 blocks of 8 English sentences containing a stress-initial bi-syllabic word followed by a test phase of 4 unique sentences, half containing the familiarized word. Monolingual infants showed a leftnegativity at 400ms, followed by a late negative component (Nc). Similarly, bilinguals show a larger negativity to familiarized than unfamiliarized words over left frontal regions, but the onset of the ERP effect was later. The results suggest that exposure to two languages with minimally different rhythmic structures increases the difficulty of finding words in the speech stream. Although bilinguals are capable of finding words in continuous speech, they make take more time to do so.