Humans engage in a wide variety of collective behaviors, ranging from simple customs like wearing a heavy coat in winter to more complex group actions, as when an audience gives applause at the close of a musical performance. Some of these collective behaviors are cases of imitation, of doing what others do. In other cases, the behavior is driven by individuals’ expectations about what certain people both do and believe others should do. When confronting real-world cases where groups act in ways that are problematic and harmful, it matters a great deal which kind of mechanism underlies the behavior. This is especially the case for those who seek to change the groups’ behavior.

In Norms in the Wild: How to Diagnose, Measure, and Change Social Norms (Oxford University Press, 2017), Cristina Bicchieri (University of Pennsylvania) lays out a nuanced theory of group behavior, establishes means for measuring individuals’ sensitivity to social norms, and explores the ways in which interventions can be designed to change social norms. The book grows out of her collaboration with UNICEF and other NGO’s devoted to initiating social change in the developing world. The details of Bicchieri’s theory of social norms are explored in her Coursera courses on “Social Norms, Social Change I” and “Social Norms, Social Change II.”