Young children extend novel words at the basic level: Evidence for the principle of categorical scope.

If young children approached the task of word learning with a specific hypothesis about the meaning of novel count nouns, they could make the problem of word learning more tractable. Six experiments were conducted to test children's hypotheses about how labels map to object categories. Findings indicated that (a) 3- and 4-year-olds function with an antithematic bias; (b) children do not reliably extend novel nouns to superordinate exemplars when perceptual similarity is controlled until ap-proximately age 7; and (c) children expect novel nouns to label taxonomic categories at the basic level, even in the presence of a perceptually compelling distractor. Results are interpreted as sup-porting the principle of categorical scope (R. M. Golinkoff, C. B. Mervis, & K. Hirsh-Pasek, 1994). How do young children, introduced to a new word, avoid the myriad, logically possible assumptions (see Quine, 1960) they might make about what the new word means? That children quickly settle on the meaning of novel words is shown by their rapid progress in vocabulary acquisition: By the end of the sec-ond year of life, children at the 50th percentile on the MacAr-thur Inventory have amassed a productive vocabulary of 324