The role of shape similarity in toddlers' lexical extensions

The taxonomic assumption, or noun-category bias, is thought to facilitate w ord learning by focusing children's attention on taxonomic categories as li kely candidates for word meanings. Three experiments were conducted to dise ntangle the role of taxonomic relations and shape similarity in 18- and 24- month-olds' responses on a noun category bias task. The relationship betwee n vocabulary composition and performance on these tasks was also examined. Results indicated that both 18- and 24-month-old children were predominantl y guided by shape similarity when extending novel labels. However, some evi dence that taxonomic information can be used to guide word extension was fo und in the 24-month-old group. Those children with a larger proportion of n ouns in their vocabulary were more likely to use information about category membership when extending words, even in the absence of shape similarity.