Theories of human behavior suggest that individuals attend to the behavior of certain people in their community to understand what is socially normative and adjust their own behavior in response.

An experiment tested these theories by randomizing an anticonflict intervention across 56 schools with 24,191 students. After comprehensively measuring every school's social network, randomly selected seed groups of 20–32 students from randomly selected schools were assigned to an intervention that encouraged their public stance against conflict at school.

Compared with control schools, disciplinary reports of student conflict at treatment schools were reduced by 30% over 1 year.

The effect was stronger when the seed group contained more "social referent" students who, as network measures reveal, attract more student attention. Network analyses of peer-to-peer influence show that social referents spread perceptions of conflict as less socially normative.

An incredible new PNAS paper by Paluck, Shepherd, and Aronow.

The finding is interesting, but those of us who run field experiments look at this social network mapping and our jaws hit the floor.