Previous natural observations have found a robust correlation between infants’ spontaneous gesture production and vocabulary development: the onset and frequency of infants’ pointing gestures are significantly correlated to their subsequent vocabulary size (Colonnesi, Stams, Koster, & Noom, 2010). The present study first examined the correlations between pointing and vocabulary size in an experimental setting, and then experimentally manipulated responses to pointing, to investigate the role of pointing in infants’ forming word-object associations.
In the first experiment, we elicited 12- to 24-month old infants’ pointing gestures to 8 familiar and 8 novel objects. Their vocabulary was assessed by the MacArthur Communicative Development Inventory (MCDI): Words and Gestures. Results showed that 12-16 month old infants’ receptive vocabulary was positively correlated to infants’ spontaneous pointing. This correlation, however, was not significant in 19-24 month old infants. This experiment thus generalizes the previous naturalistic observation findings to an experimental setting, and shows a developmental change in the relation between pointing and receptive vocabulary. Together with prior studies, it suggests a possible positive social feedback loop of pointing and language skills in infants younger than 18 months old: the bigger vocabulary size infants have, the more likely they point, the more words they hear, and then the faster they develop their vocabulary.
In the second experiment, we tested whether 16-month-old infants’ pointing gestures facilitate infants’ word learning in the moment. Infants were randomly assigned to one of three conditions: the experimenter labeled an unfamiliar object with a novel name 1) immediately after the infant pointed to it (the point contingent condition); 2) when the infant looked at it; or 3) at a schedule predetermined by a vocabulary-matched infant in the point contingent condition. After hearing the objects’ names, infants were presented with a word learning test. Results showed that infants successfully selected the correct referent above chance level only in the point contingent condition, and their performance was significantly better in the point contingent condition than the other two conditions. Therefore, only words that were provided contingently after pointing were learned. Taken together, these two studies further our understanding of the correlation between early gesture and vocabulary development and suggest that pointing plays a role in early word learning.