Developmental course of the temporal relationship between gaze direction and vocal production in typical and Down's syndrome infants

Abstract

This study was aimed at examining the temporal relationship between gaze and vocal production behaviour among typically developing infants, infants with Down's syndrome, and their mothers. If gaze–voice timing behaviour is an organizing principle of communicative interaction in typical population, then studying it should provide insight into how children with Down's syndrome and their mothers use this temporal relationship to structure their exchanges. Forty-four mother–infant dyads (22 dyads with a Down's syndrome child and 22 with a typical child) were observed. The developmental course of timing pattern was not different between DS and typically developing infants from 4 to 19 months (DA). Insofar as the timing patterns differed between DS and typical infants at 20 months, this could be explained by their differing level of language acquisition. With the use of language, the timing patterns will reappear equal in the both populations. Results suggest that (i) the children's behaviours could be partially explained by the behaviours of their mothers. The mother–child dyad would be the mould that shapes the child's future sociolinguistic skills, and (ii) for the two populations, the timing-pattern changes could be explained by the emergence of language.