Verification of property statements by retarded and nonretarded adolescents.

Educable mentally retarded and nonretarded adolescents verified true and false statements about the properties of common objects. For the true sentences, one-half contained properties rated as highly salient to the given object, and half contained less salient properties. Further, at each level of salience, one-half of the properties were static (physical) properties, e.g., "Carrots are orange," and half were action properties, e.g., "Rabbits can hop." True verification times were more rapid for all subjects when sentences contained highly salient properties. In addition, sentences containing action properties were verified faster than those containing static properties, but only by the retarded subjects (whose response times were slower overall). Additional analyses indicated that the retarded subjects responded particularly rapidly to action properties that designate "what can be done to an object" (extrinsic-action properties) as opposed to "what an object can do" (intrinsic-action properties). These findings were discussed in relation to the organization of semantic knowledge and the apparent group differences in the weighting of semantic features.