EFFECTS OF CATEGORY DOMAINS AND INFORMATION TYPES ON CATEGORY-BASED INFERENCES IN CHILDREN AND ADULTS

Inferences are assumed as processes which one draws some conclusions f rom the premises. Category-based inferences consist of deductive infer ences which the category levels in the conclusion are lower than those in the premise and inductive inferences which the category levels are the same or higher than those in the premise. The subjects were given the new informations with the verb 'do' (function information) or 'ha ve' (part information) in the premise statements, and then required to judge whether the informations were true for the conclusion statement s. Deductive inferences were much easier than inductive ones, which we re explained by assuming that the subjects drew deductive inferences b y generalizing the extensional knowledge about categories in the premi se and inductive inferences by the similarity between the premise and conclusion category terms. The age difference was found mainly for the deductive inferences. The inferences in the living-thing category wer e prompted by the function information, whereas those in the food cate gory were prompted by the part information. Thus, the subjects were se nsitive to the category domains within the same natural kinds and the information types. The findings suggested that existing knowledge abou t the dynamic category such as living thing was activated by the funct ion information, whereas exixting knowledge about the static category such as food was activated by the prat information.