 Category membership

Category membership concerns whether an object or event is assigned to a specified category. It is distinct from its judged typicality, how confident a person is about the judgment and how quickly the judgment is made. A category can have a precise membership rule while its examples differ in familiarity.

For example, 3 and 97 are both odd integers: each has the form $2k+1$ for an integer $k$. A participant might nevertheless consider one a more typical example or identify it faster. Those responses concern the categorization process, rather than making one integer mathematically more odd than the other.

Sharon Lee Armstrong and collaborators compared typicality judgments and category verification for everyday categories and well-defined categories including odd and even numbers. Their experiments show why graded responses alone cannot establish that the underlying membership conditions are graded. Distinguishing membership, typicality and reaction time avoids drawing a stronger representational conclusion than the task supports.^[ref]