Parent Speech in Free Play Is Guided by Infant Attention, But Organized by Object Familiarity.

Successful coordination of infant attention and parent speech during free play supports infants' language development. Parents' responsive linguistic input reduces uncertainty in label-referent associations and provides information at moments of infants' increased attention and receptiveness. While infants frequently lead the dyads' focus of attention, parent speech has been shown to scaffold infants' attention toward fixated objects. So far, however, little is known about the qualitative characteristics of parent speech during such interactions, and their effects on infants' attention. Here, we analyzed the role of the content and communicative intent of caregivers' speech to their 18-month-old infants (N = 31) during free play when infants or parents led an interaction, and when parent speech co-occurred with infants' sustained attention. Interactions were most likely to be infant-led, both temporally and topically, and parents' topically aligned, but not misaligned speech was associated with infants' sustained attention. Qualitative analysis of speech types revealed mostly object-focused speech in interactions with familiar objects, but a broader range of speech types in interactions with novel objects. We explain this pattern by suggesting that speech in interactions with familiar objects is structured by shared experience, whereas the lack of common ground with novel objects potentially induces parents to use more varied speech to engage their infants.