Nouns mark category relations: Toddlers' and preschoolers' word-learning biases. Child Developmental

suggests that preschool children approach the task of word leaming equipped with implicit biases that lead them to prefer some possible meanings over others. The noun-category bias proposes that children favor category relations when interpreting the meaning of novel nouns. In the series of experiments reported here, we develop a stringent test of the noun-category bias and reveal that it is present in children as young as 2 years of age. In each experiment, children participated in a 5-item match-to-sample task. Children were presented with a target item (e.g., a cow) and 4 choices, 2 of which belonged to the same superordinate category as the target (e.g., a fox and a zebra) and 2 of which were thematically related to the target (e.g., milk and a bam). In Experiment 1 we demon-strate that novel nouns prompt preschool children to attend to superordinate-level category rela-tions, even in the presence of multiple thematic alternatives. In Experiment 2, we ascertain that the bias is specific to nouns; novel adjectives do not highlight superordinate category relations. In Experiment 3, we demonstrate the noun-category bias in 2-year-olds. The nature and utility of the noun-category bias are discussed. Developmental research over the last de- gists. For, in principle, children's flexible ap-cade has documented remarkable cognitive preciation of different conceptual relation