Contingency drives children's vocal behavior

Behavior analysts have studied the development of early vocal behavior in the context of infant-caregiver interactions. In the current article, we focus on two specific aspects of a caregiver's contingent response to infant vocalizations: contingent vocal imitation, which involves an adult imitating the speech sounds emitted by the child, and parentese, which involves short phrases with high pitch, exaggerated intonation, and slower tempo. We present the evidence for (a) effects of these forms of contingent responding on children's vocalizations and (b) effective intervention in studies with clinical populations. We highlight key aspects of prior studies, including methodological and procedural details and the observed effects on the frequency and quality of children's vocalizations. We discuss the potential mechanisms underlying the observed effects on children's vocal responses, including conditioning, social reinforcement, automatic reinforcement, and evolutionary adaptations. We discuss clinical implications for practitioners and identify 10 critical areas for future research.