RUBIA INFANTI & EBRU YILMAZ (Laboratoire Ethologie, Cognition, Development -EA 3456-, University Paris-West, France)

Infants are known to engage in conversation-like exchanges from the end of the second month after birth. These ‘protoconversations’ involve both turn-taking and overlapping vocalization. Previous research has shown that the timing of adult-infant turn-taking sequences is close to that of adult verbal conversation. The gap between turns in protoconversational exchange seldom exceeds 500ms. It has also been shown that young infants adjust the quality of their vocalization in response to the quality and timing of adult vocalization. Furthermore, turn-taking exchanges often involve mutual imitation of sounds, pitches and melodic contour. We present new evidence of the timing and temporal organization of turn-taking interaction between mothers and 2 to 4-month-olds recorded in naturalistic contexts based on a corpus of recordings from 50 French dyads. All of them were recorded in naturalistic contexts, in their home, when infants were in a quiet alert state. The entire sample comprised a total of 2943 vocalizations of which 748 (25.4%) were produced by the infants, 1851 (62.9%) were produced by the mothers, and 344 were overlapping vocalizations (11.7%). In all, 489 turns taking sequences were identified. The quality and duration of infant vocalizations differed according to whether or not they were produced within a turn-taking sequence. Finally, length and number of turns were highly correlated between mothers and infants vocalizations.