Labels are one source of our judgments. By assigning labels to objects, we not only create references but we also group prior and current experiences together. The goal of this research is to investigate how labels influence our judgments. Previous research on inductive generalization shows that labels can be more important than physical characteristics (the labeling effect), but the mechanism for this effect remains unclear. There are two differing views regarding the role of labels. One view proposes that labels are not essentially different from physical features: shared labels increase overall similarity between two items in the same way as shared physical features. The other view suggests that people have a naive theory that shared labels are more special than shared physical features. The goal of this dissertation is to provide evidence that complements these conflicting views. I suggest that the role of labels varies depending on the background knowledge: types of categories (living things vs. man-made objects), amount of knowledge (number of exemplars people could list for the category), and types of labels (categorical vs. indexical). The results from four experiments showed that, for living things, the labeling effect is strong and depends less on the amount of knowledge; for man-made objects, the labeling effect is weak and depends on the amount of knowledge.
