For a policy-maker promoting the end of a harmful tradition, conformist social influence is a compelling mechanism. If an intervention convinces enough people to abandon the tradition, this can spill over and induce others to follow. A key objective is thus to activate such spillovers and amplify an intervention’s effects. With female genital cutting as a motivating example, we develop empirically informed analytical and simulation models to examine this idea. Even if conformity pervades decision-making, spillovers can range from irrelevant to indispensable. Our analysis highlights three considerations. First, ordinary forms of individual heterogeneity can severely limit spillovers, and understanding the heterogeneity in a population is essential. Second, although interventions often target samples of the population biased towards ending the harmful tradition, targeting a representative sample is a more robust way to achieve spillovers. Finally, if the harmful tradition contributes to group identity, the success of spillovers can depend critically on disrupting the link between identity and tradition.
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For valuable comments while developing this research, we thank J. Walsh, as well as seminar participants at the universities of Bern, Konstanz, Lausanne, Nottingham and Zurich, the United Nations University in Maastricht, Harvard, and Oxford. C.E. and S.V. also thank the Swiss National Science Foundation (grant number 100018_185417/1). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
The authors declare no competing interests.
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Model details, including Supplementary equations (1)–(25) and Supplementary Figs. 1–54; and Supplementary References.
A brief guide explaining Supplementary Software 1–4.
Custom code for plotting how a policy-maker’s choices affect the distribution of threshold values.
Custom code for agent-based simulations under heterogeneity in preferences, responses to the intervention, and networks.
Custom code for numerically simulating a system of difference equations combining ingroup conformity with outgroup anti-conformity.
Custom code for agent-based simulations combining ingroup conformity with outgroup anti-conformity.
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Efferson, C., Vogt, S. & Fehr, E. The promise and the peril of using social influence to reverse harmful traditions. Nat Hum Behav 4, 55–68 (2020). https://doi.org/10.1038/s41562-019-0768-2
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