Estimating infants’ age from mothers’ infant-directed speech

Abstract

Speech varies depending on the characteristics of the speaker as well as the recipient. Infant-directed speech (IDS) is a well-known example where individuals modify their speech when addressing infants and children. Adults readily identify IDS and infer speakers’ intentions from it, even when it is in a foreign language. Given that IDS shows variability depending on the age of the child, the aim of the present study was to investigate whether adults can make estimations regarding the age of the child by listening to IDS directed to children of different ages. Native speakers of Turkish with varying degrees of English knowledge listened to naturalistic speech recordings of English-speaking mothers (N = 186). Participants were randomly assigned to listen, either to the original recordings, or to the low-pass filtered versions. After hearing the two segments, participants were asked to guess which speech segment had addressed a younger or an older child. Overall, participants’ guesses were correct above chance level, and performance was better in the non-filtered condition compared to the filtered condition. There was a positive relationship between participants’ performance and their English level. Participants who had children performed better than those who didn’t have children. Finally, the probability of making accurate estimations was predicted by the age difference between the paired segments. These results suggest that adults are sensitive to age-related cues in IDS. Even though this sensitivity is influenced by experience and content, it does not solely depend on these factors.