Perceptual alignment contributes to referential transparency in indirect learning

Young children can sometimes acquire new word meanings—even for property terms—through incidental learning (e.g. Carey & Bartlett, 1978). We propose that an important support for this process is spontaneous perceptual comparison processes that lead children to notice key commonalities and differences. Specifically, we hypothesize that when the target property appears as a difference between two highly similar and alignable objects, spontaneous comparison processes operate to highlight the property. The property may then be linked to an accompanying word, even if the child has no prior intention to learn the word. To test this, we revisited the Carey and Bartlett paradigm, varying the perceptual alignability of the objects that 3- and 4-year-olds saw while hearing a novel color word, chromium. In Experiments 1 and 2, children in the High Alignment condition were able to identify chromium objects in a subsequent task, whereas those in the Low Alignment condition were not. Experiment 3 showed that direct instructions to learn the word led to a different pattern of results. Experiment 4 showed that the incidental learning persisted over delay and transferred to new objects. We conclude that perceptual alignment contributes to referential transparency and to incidental learning of word meanings. Implications for hypothesis-testing theories of word learning are discussed.