Comparing Language Input in Homes of Blind and Sighted Children: Insights from Daylong Recordings

We compared everyday language input to young congenitally-blind children with no additional disabilities (N=15, 6--30mo., M:16mo.) and demographically-matched sighted peers (N=15, 6--31mo., M:16mo.). By studying whether the language input of blind children differs from their sighted peers, we aimed to determine whether, in principle, the language acquisition patterns observed in blind and sighted children could be explained by aspects of the speech they hear. Children wore LENA recorders to capture the auditory language environment in their homes. Speech in these recordings was then analyzed with a mix of automated and manually-transcribed measures across various subsets and dimensions of language input. These included measures of quantity (adult words), interaction (conversational turns and child-directed speech), linguistic properties (lexical diversity and mean length of utterance), and conceptual features (talk centered around the here-and-now; talk focused on visual referents that would be inaccessible to the blind but not sighted children). Overall, we found broad similarity across groups in speech quantity, interaction, and linguistic properties. The only exception was that blind children's language environments contained slightly but significantly more talk about past/future/hypothetical events than sighted children's input; both groups received equivalent quantities of "visual" speech input. The findings challenge the notion that blind children's language input diverges substantially from sighted children's; while the input is highly variable across children, it is not systematically so across groups, across nearly all measures. The findings suggest instead that blind children and sighted children alike receive input that readily supports their language development, with open questions remaining regarding how this input may be differentially leveraged by language learners in early childhood.