Children's use of polysemy to structure new word meanings

It is well-known that children rapidly learn words, following a range of heuristics. What is less well appreciated is that-because most words are polysemous and have multiple meanings (e.g., "glass" can label a material and drinking vessel)-children will often be learning a new meaning for a known word, rather than an entirely new word. Across 4 experiments we show that children flexibly adapt a well-known heuristic-the shape bias-when learning polysemous words. Consistent with previous studies, we find that children and adults preferentially extend a new object label to other objects of the same shape. But we also find that when a new word for an object ("a gup") has previously been used to label the material composing that object ("some gup"), children and adults override the shape bias, and are more likely to extend the object label by material (Experiments 1 and 3). Further, we find that, just as an older meaning of a polysemous word constrains interpretations of a new word meaning, encountering a new word meaning leads learners to update their interpretations of an older meaning (Experiment 2). Finally, we find that these effects only arise when learners can perceive that a word's meanings are related, not when they are arbitrarily paired (Experiment 4). Together, these findings show that children can exploit cues from polysemy to infer how new word meanings should be extended, suggesting that polysemy may facilitate word learning and invite children to construe categories in new ways.