Publication Type: Individual Poster
Abstract: Background and Aims: Language learners need to identify a person’s verbal referent(s). When adults follow another’s gaze they interpret the look as ‘referring to’ or being ‘about’ the target that is being looked at. Infants may also make this referential inference, or at least a rudimentary link between the looker and target. In the current study we investigate whether gaze following predicts later language development in a longitudinal study. Specifically, does infant gaze-following behavior predict rate of vocabulary growth?
Methods: At 10 or 11 months old, infants saw an adult turn her head and eyes toward one of two distal targets. In each of 4 trials, the adult looked at a target without giving any vocal or gestural cues. Infants’ looks to the target were scored as either correct (adult’s target) or incorrect (opposite target). On each 6.5-trial, the duration of the first correct look was measured. The looking duration score was the average duration of correct looks and had an observed range of 0 to 4.12 seconds. Language development was measured by MacArthur-Bates Communicative Developmental Inventory at 10-11, 14, 18, 24 and 30 months (N=31). Parents reported their infants’ words produced and 3 longest utterances (latter at the older three ages).
Key Results: We examined individual growth trajectories for total number of words produced and mean length of the 3 utterances (MLU3L) with hierarchical linear models. Looking duration was a significant predictor of words produced per month, p < .001. For each second infants looked longer at a correct target they had an estimated advantage of 4.15 words per month, which resulted in a predicted 299-word advantage for long (4 s) lookers by 30 months of age. The looking duration score was also a significant predictor of MLU3L, p < .0001. The average advantage was 0.14 morphemes per month for each second longer in the duration score. Maternal education and child gender did not significantly improve the models.
Conclusions: Infants’ gaze-following behavior at 10-11 months predicts subsequent rate of growth in vocabulary size and utterance length. This advantage may stem from infants using the link between the looker and the object to discern a speaker’s referent. Theories linking infant social cognition to language acquisition will be discussed.