Comparing Utterance Types and Contents in the Input to Blind and Sighted Infants

Blind infants cannot acquire information about the world using vision, which may make it more difficult to connect words they hear to referents that, for sighted infants, are readily visually available. We ask whether, in light of this, caregivers talk differently to blind vs. sighted infants. We consider two qualitative dimensions of speech input: the types of utterances it contains, and the content of those utterances. Using daylong LENA audio-recordings, we captured naturalistic speech in the homes of blind and sighted infants (n=15 each, aged 6-30 months).We systematically subsampled and transcribed 40 minutes per child; these transcripts were then analyzed across various dimensions tapping e.g. syntactic structure, informativity, and conversational features. Overall, we found highly similar distributions of utterance types and content across the speech heard by the children in each group.Fine-grained analysis revealed blind children's language environments contained slightly but consistently more declaratives compared to sighted peers, with other categories showing no differences across the board. These findings show that parents in both groups talk to their children in similarly informative ways, challenging claims that blind infants hear more directives and commands.More broadly, this work expands on prior research suggesting that stark differences in caretaker input are unlikely to explain blind and sighted infants' early language development.