Conversational skills: Detection of turn-taking violation in 6-month-old infants

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Turn-taking is an important characteristic of everyday life communication. During a conversation, speakers and listeners alternate smoothly their roles and participants avoid overlaps and extensive gaps between conversational turns (Sacks et al, 1974). A child needs more than 3 years to handle turn-taking skills although alternated vocalizations between a child and his/her parents become predominant before a child is 9 months old (Casillas et al, 2015; Jasnow, 1986). Our experiment aimed to assess the ability of 6-month-old infants to perceive a breach of turn-taking characteristics, namely an overlap. To do so, the infants (N=40) watched videos of three sketches in which two women spoke to them. Three different situations were presented to each infant: 1) the first speaker turned toward the second to allow her to speak; 2) the second speaker started speaking right at the end of the first speaker's sentence; 3) the second speaker started speaking before the end of the first speaker's sentence (=overlap). The pictures of both speakers were presented side by side before and after each sketch. Sketches were shown in a random order and speakers differed between sketches. We measured the time infants looked at each speaker before and after each sketch. Six-month-old infants looked longer to the second speaker after she realized an overlap in the conversation. However, this behavioral response was only observed when the infants had previously seen two sketches with a respected turn-taking. Thus, their reaction to an overlap depended on their short-term experience. Six-month-old infants need to be exposed to correctly alternated turns to detect subsequently a breach in an interaction. Nevertheless, this suggests that the precursor of overlap perception by infants occurs around 6 months, even before they are able to alternate smoothly their vocalizations with their parents.