With this commentary, I raise two issues relevant to the theoretical framework from a developmental perspective. First, the infants' emotional responses are induced by the music as well as by the multimodal information they perceive in interaction with their mothers, and these responses change with time. Second, contrary to what is suggested in the target article, musical expectancy is already experienced by young infants.

In this commentary we raise three issues: (1) Is it motherese or song that sets the stage for very early mother-infant interaction? (2) Does the infant play a pivotal role in the complex temporal structure of social interaction? (3) Is the vocal channel primordial or do other modalities play an equally important role in social interaction?