When knowing the name of objects is not enough to categorize them

Two experiments explored 16-month-olds' learning of new nouns, and their use of these nouns to categorize objects. In both experiments, infants were presented with triads of perceptually dissimilar objects, which were given made-up names, two of the objects receiving the same name. Following each training phase, infants were tested on whether: (a) they could use the names to categorize the objects (Experiment 1), or (b) they had actually learned the association between the names and the objects (Experiment 2). Our results show that 16-month-olds can simultaneously learn the name of three objects, but cannot use these newly learned names to categorize the objects in the absence of any other cue to categorization. These results are discussed in light of different hypotheses regarding the way infants come to use names to categorize objects.