Inductive judgments about natural categories

The present study examined the effects of semantic structure on simple inductive judgments about category members. For a particular category (e.g., mammals), subjects were told that one of the species (e.g., horses) had a given property (an unknown disease) and were asked to estimate the proportion of instances in the other species that possessed the property. The results indicated that category structure—in particular, the typicality of the species—influenced subjects' judgments. These results were interpreted by models based on the following assumption: When little is known about the underlying distribution of a property, subjects assume that the distribution mirrors that of better-known properties. For this reason, if subjects learn that an unknown property is possessed by a typical species (i.e., one that shares many of its properties with other category members), they are more likely to generalize than if the same fact had been learned about an atypical species.