Articulating while listening supports the emerging perception-production link in early infancy

There is a growing body of work in infant speech perception proposing that the auditory analysis of speech is coupled with articulatory information involved in speech production. These studies show that the link between perception and production emerges early in infancy, and before infants have some experience with speech production. However, the mechanisms behind the development of this link are not well understood. Importantly, research has not yet addressed whether infants produce speech-driven articulatory movements when perceiving speech. To address this question, we employed ultrasound imaging to record the tongue shapes of 6-month-old infants while listening to vowel-consonant-vowel sequences that differed in the articulatory configuration of the consonant. If tongue shape varied as a function of the speech token heard, listening to a dental sound like /t/, and to a velar sound like /k/, would trigger differences in tongue shape. The results confirmed this prediction, showing that infants produced articulatory movements by placing the tongue more to the front or back in the direction of the sounds they heard. Our findings are the first to suggest that infants engage in speech driven oral-motor responses modulated by the sounds perceived, advancing our understanding of the mechanisms for the emerging perception-production link.