Word comprehension facilitates object individuation in 10- and 11-month-old infants

The present study investigated the role that comprehending words for objects plays in 10- and 11-month-old infants' ability to individuate those objects in a spatiotemporally ambiguous event. To do this, we employed an object individuation task in which infants were familiarized to two objects coming in and out from behind a screen in alternation, and then the screen was removed to reveal either both or only one of the objects. Results show that only when 10- and 11-month-olds comprehend words for both objects seen do they exhibit looking behavior that is consistent with object individuation (i.e., looking longer when one of the objects is surreptitiously removed). Neither level of object permanence reasoning nor overall receptive vocabulary had an effect on performance in the object individuation task, indicating that the effect was specific to the immediate parameters of the situation, and not a function of overall precocity on the part of the succeeding infants. These results suggest that comprehending the words for occluded/disoccluded objects provides a kind of "glue" which allows infants to bind the mental index of an object with its perceptual features (thus precipitating the formation of two mental indexes, rather than one). They further suggest that a shift from object indexing driven by the where (dorsal) system to one which is driven by integration of the ventral and dorsal neural systems, usually not observed until 12 months of age, can be facilitated by word comprehension in 10- and 11-month-old infants.