Social categorization is an early-developing feature of human social cognition, yet the role that
social categories play in how children understand and predict human behavior has been unclear.
These studies test whether a foundational functional role of social categories is to mark people as
intrinsically obligated (e.g., to protect, not to harm) to one another. In three studies, children
(ages 3-9, N = 124) viewed only within-category harm as violating intrinsic obligations; in
contrast, they viewed between-category harm as violating extrinsic obligations defined by
explicit rules. These data indicate that children view social categories as marking patterns of
intrinsic interpersonal obligations, suggesting that a key function of social categories is to
support inferences about how people will relate to members of their own and other groups.