Indexical and linguistic processing in infancy: Discrimination of speaker, accent and vowel differences

Infants preferentially discriminate native speechsound categories prior to acquiring a large receptive vocabulary, implying a major role for distributional learning strategies in phoneme learning. However, it is unknown how infants extract the vowel phonemes of their language from distributional information in the presence of between-speaker variability in vowel realizations. Before we can ask this question, we must determine whether both indexical and linguistic cues are available to infants in speech processing. We familiarized infants to tokens of a vowel produced by one speaker, and tested their listening preference to trials containing a vowel change produced by the same speaker (linguistic information), and the same vowel produced by a speakers of the same or a different accent (indexical information). Infants noticed linguistic and indexical differences, suggesting that both are salient in infant speech processing. Further research should explore how infants weight these cues in distributional learning of vowel categories.