28.02.23 - Morgane Jourdain

In this talk we discuss the role of child-directed speech (CDS) for language evolution. We show that there are structural and acoustic differences between responsive CDS (utterances used by adults following a child utterance) and CDS in general. We show that adults attune to children more in responsive CDS in simplifying their utterances more strongly than in overall CDS, and that this attunement correlates with the complexity of the child’s preceding utterance. To test whether this attunement is an implicit teaching mechanism restricted to CDS or rather a species general mechanism of human communication, we also test adult-adult behavior. We find that this attunement is also present in adult-adult responsive utterances. We propose that the well-known mechanism of accommodation (gradual adaption of a speaker to the speech features of her interlocutor) is the result of a more general mechanism of imitation. This suggests that simplification in CDS is not the result of a mechanism specific to that register, but rather a universal mechanism of human communication. We propose that this sheds light on innate learning mechanisms relevant for first language acquisition and the evolution of language.