Category Exceptions Change Category Boundaries

In order to successfully guide generalization of knowledge, category representation needs to be both: flexible enough to account for new evidence and stable enough to resist harmful change. Here we present a set of experiments designed to test how items that violate our expectations (i.e., category exceptions) affect category representation. Specifically, we wanted to know whether learning a category exception can change category boundaries. Does learning about penguins changes the way we think about birds? Do features of penguins contribute to making decisions as to whether a novel item is a bird? Across two experiments we found evidence that exceptions can change category boundaries and thus significantly affect future generalization. We discuss implications these findings have for the extent models of category learning and memory