INCODE · INtersensory Cooperation in phonological DEvelopment

INtersensory Cooperation in phonological DEvelopment

During the first year of life, infants learn to recognize and produce speech sounds. Proficiency in these phases is crucial for later linguistic and educational outcomes. The main achievements accomplished by infants in this period have been unveiled. Yet, the sensory bases of these processes are still unclear. Spoken language is a complex signal entailing the action of phono-articulation and its resulting sound (speech). Traditionally, speech perception has been regarded as an auditory-based ability. However, evidence has shown that speech actions do also carry perceptual correlates. In adults, the brain network recruited by speech processing includes the sensorimotor areas underlying speech production (Skipper, Devlin & Lametti, 2017), co-activation testifying of a strict action/perception association. Thus, contemporary investigations on language development cannot neglect sensorimotor processes: this would amount to ignore the ontogenesis of a sensory channel that is active in adults. Evidence on the function of sensorimotor processes in early speech development is still poor (Vilain et al., 2019). However, infancy constitutes an ideal context of investigation, as during this period the anatomy and neurocognitive control of the speech sensorimotor apparatus begins its maturation (Guellaï, Streri & Yeung, 2014): when, how, why do sensorimotor processes begin to play a perceptual role, in language? Which advantages are carried by this intersensory binding? Recent studies have shown that, once infants have learnt to produce a given speech sound, they also display a boost in its perception (ex. Vilain et al., 2019; DePaolis et al., 2010, Lorenzini & Nazzi, 2022). More surprisingly, another series of studies have also shown that, before the onset of production, infants can recruit sensorimotor information for perceptual purposes if they are put under appropriate conditions (infant-friendly manipulations of the articulatory organs, Choi et al., 2021). This results prove the existence of precocious sensorimotor processes in language development and suggest that the sensorimotor system might play an important role in language learning. More studies are needed to detail the functional role possibly played by sensorimotor processes in the context of early linguistic achievements. INCODE aims to shed light on these research questions as follows. Experiment 1: is there a relationship between speech-related sensorimotor development and the processing of speech sounds? In particular: is there a link between infants' abilities to articulate consonant sounds and their rapidity in developing perceptual biases concerning consonant processing (ex., Nishibayashi & Nazzi, 2016. https://doi.org/10.1016/j.cognition.2016.07.003)? Experiment 2: can we identify changes in the neural correlates of speech sounds processing before and after speech-related sensorimotor knowledge is developed, through the onset of babbling?

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