The temporal coordination of early infant communication.

The ability to coordinate expressive behaviors is crucial to the development of social and emotional communication. Coordination involves systematic sequencing of behaviors from two different modalities that have some temporal overlap. A bootstrapping procedure was used to determine whether preverbal 3- and 6-month-old infants sequence vocalizations, gazes at their mothers' faces, and facial expressions into pairs of coordinated patterns nonrandomly. Smiles and frowns were highly coordinated with vocalizations. Smiles were also coordinated with gazes at mothers' faces, which became stronger with age. Vocalizations were not coordinated with gazes at mothers' faces. These findings illustrate the manner in which infants temporally coordinate communicative actions and provide new evidence that facial expressions (particularly smiles) are central to early infant communications.