The origins of intentional vocalizations in prelinguistic infants.

The development of the intention to communicate was examined by attempting to identify the point at which prelinguistic vocalizations are used by infants as a means of communication. This achievement was related to the infants' cognitive development. It was hypothesized that Piagetian stage 5 in the development of causality may be a prerequisite for the intentional use of vocalizations. 46 infants (X age = 10.7 months, range: 8 months--14.3 months) and their mothers were videotaped in a structured, naturalistic setting. 2 "frustration" episodes were devised to encourage communication, and the infants' vocalizations as well as other behaviors were coded by 2 observers. 2 Piagetian tasks were selected to assess the causal developmental level of the child. A significant relationship between causal developmental level and the occurrence of intentional vocalizations was found. The results support the hypothesis that stage 5 causal development may be a prerequisite to the use of intentional vocalizations.