Plasticity in older infants’ perception of non-native speech sounds: The role of selective attention in context

Developmental plasticity is the ability of extant conditions and circumstances to increase variability in phenotypic expression throughout the lifespan. During human infancy, plasticity expands and contracts depending on domains of functioning, developmental history, and timing. In terms of language processing, young infants attend to and discriminate contrastive sounds within both native and non-native phonetic systems, but become selectively attuned to native sounds by the end of the first year. However, studies relevant to this decreasing sensitivity in phoneme perception have not always included factors that are emerging as powerful promoters of attention such as infant-directed speech (IDS), synchronous multimodal face+voice presentations, and female speakers. We investigated whether English-learning 11-month-olds would discriminate a non-native Hindi phoneme contrast with these factors in place. Results showed significant discrimination of the Hindi contrast, regardless of speech register, provided the sounds were presented by a dynamic female speaker. Interestingly, when a dynamic male IDS speaker was used, no significant discrimination was found. These results demonstrate plasticity in non-native speech perception contingent upon inducing and supporting selective attention. Multimodal information emanating from female speakers promoted perception of challenging non-native sounds, demonstrating the power of context for language learning in early development.