The present study investigated the degree to which an infants’ use of simultaneous gesture–speech combinations during controlled social interactions predicts later language development. Nineteen infants participated in a declarative pointing task involving three different social conditions: two experimental conditions (a) available, when the adult was visually attending to the infant but did not attend to the object of reference jointly with the child, and (b) unavailable, when the adult was not visually attending to neither the infant nor the object; and (c) a baseline condition, when the adult jointly engaged with the infant's object of reference. At 12 months of age measures related to infants’ speech-only productions, pointing-only gestures, and simultaneous pointing–speech combinations were obtained in each of the three social conditions. Each child's lexical and grammatical output was assessed at 18 months of age through parental report. Results revealed a significant interaction between social condition and type of communicative production. Specifically, only simultaneous pointing–speech combinations increased in frequency during the available condition compared to baseline, while no differences were found for speech-only and pointing-only productions. Moreover, simultaneous pointing–speech combinations in the available condition at 12 months positively correlated with lexical and grammatical development at 18 months of age. The ability to selectively use this multimodal communicative strategy to engage the adult in joint attention by drawing his attention toward an unseen event or object reveals 12-month-olds’ clear understanding of referential cues that are relevant for language development. This strategy to successfully initiate and maintain joint attention is related to language development as it increases learning opportunities from social interactions.

This research was funded by a Recercaixa 2013–2015 project to Pilar Prieto and two projects from the Spanish MINECO (BFU2012-31995 to Pilar Prieto and PSI-2011-25376 to Laura Bosch). We would like to thank all GrEP and APAL Lab members for their support and comments to earlier versions of this paper, and especially Jorgina Solé for help in sample recruitment and testing assistance, and Joan Borràs-Comes for his help with the statistical analysis of the data. We are grateful to all the subjects and their families for having participated in this longitudinal study.