Abstract
Infants perceptually tune to the phonemes of their native languages in the first year of life, thereby losing the ability to discriminate non-native phonemes. Infants who perceptually tune earlier have been shown to develop stronger language skills later in childhood. We hypothesized that socioeconomic disparities, which have been associated with differences in the quality and quantity of language in the home, would contribute to individual differences in phonetic discrimination. Seventy-five infants were assessed on measures of phonetic discrimination at 9 months, on the quality of the home environment at 15 months, and on language abilities at both ages. Phonetic discrimination did not vary according to socioeconomic status (SES), but was significantly associated with the quality of the home environment. This association persisted when controlling for 9-month expressive language abilities, rendering it less likely that infants with better expressive language skills were simply engendering higher quality home interactions. This suggests that infants from linguistically richer home environments may be more tuned to their native language and therefore less able to discriminate non-native contrasts at 9 months relative to infants whose home environments are less responsive. These findings indicate that home language environments may be more critical than SES in contributing to early language perception, with possible implications for language development more broadly.