Behavioral Communities and the Atomic Structure of Networks
2026-01-28
When people coordinate their behaviors with their friends—e.g., choosing whether to adopt a new technology, protest against a government, attend university—divisions within a social network can lead to contrasting norms of behavior in different parts of the network. We define a society’s atoms to be groups of people who adopt the same behavior in every equilibrium. We show that the atoms are at least as coarse as blocks in stochastic block models, and that using knowledge of the atoms to seed the diffusion of a behavior significantly increases diffusion compared to seeding based on standard community detection algorithms. (JEL D85, D91, Z13)