The role of comparison in the extension of novel adjectives.

Previous reseach has documented that basic-level object categories provide an initial foundation for mapping adjectives to object properties. Children ranging from 21 months to 3 years can successfully extend a novel adjective (e.g., transparent) to other objects sharing a salient property if the objects are all members of the same basic-level category; if the objects are members of different basic-level categories, they fail to extend adjectives systematically (R. S. Klibanoff & S. R. Waxman, 2000a; S. R. Waxman & D. B. Markow, 1998). The present study proposed that the process of comparison is instrumental in children's ability to move beyond this foundation. To promote comparison, 2 target objects were introduced to 3-year-olds. In Experiment 1, the targets had contrastive properties (e.g., 1 transparent and 1 opaque object); in Experiment 2, the targets had consistent properties (e.g., 2 transparent objects). The results of both experiments illustrate that comparison--a general psychological process--operates in conjunction with naming to support the extension of novel adjectives to properties of objects from diverse basic-level categories.