Developmental trajectories in infant pointing: the effects of vocalisation and communicative intention

The goal of this intensive longitudinal study was to trace the developmental trajectories of infant pointing production, through consideration of the modality (i.e. pointing alone vs pointing–vocal coupling) and the communicative intention (i.e. imperative vs declarative). Multilevel analysis was used to model the normative trend and the individual differences in pointing trajectories. Eighteen Italian infants participated in this study and were followed monthly from 9 to 18 months of age. The infants were involved in a structured task designed to elicit imperative and declarative pointing (T-POINT). The proportion of pointing for each participant as a function of age, modality (pointing alone vs pointing–vocal coupling) and context (imperative vs declarative), and the interactional effects, were modelled. Random effects among participants for age trends were estimated. This analysis defined the following: (1) a significant linear increase in pointing production, without and with vocalisation; (2) a significant increase in pointing–vocal coupling over pointing produced alone, in an accelerated form; (3) that the context does not appear to moderate linear and quadratic trends; and (4) that infants differed in their developmental trajectories with respect to the quadratic component, which means that some of the infants developed faster with age than the others. Results are discussed with respect to the hypothesis of strong integration between different systems of communication, further underlining the progression of pointing–vocal coupling.