How Little Does It Take to Trigger a Peer Effect? An Experiment on Crime as Conditional Rule Violation

By Christoph Engel

Objectives: Peer effects on the decision to commit a crime have often been documented. But how little does it take to trigger the effect? Method: A fully incentivized, anonymous experiment in the tradition of experimental law and economics provides fully internally valid causal evidence. A companion vignette study with members of the general public extends external validity. Results: (a) the more of their peers violate an arbitrary rule, the more participants do; (b) a minority has a threshold and switches from rule-abiding to violation once a sufficient number of their peers violate the rule; (c) the more the rule is constraining, the more participants are sensitive to the number of others who violate the rule; (d) if participants do not have explicit information about the incidence of rule violations in their community, they rely on their beliefs. Conclusion: In terms of substance, the paper shows that mere social information is the core of peer effects. In terms of methodology, the paper demonstrates the power of incentivized, decontextualized lab experiments for isolating mental building blocks of the decision to commit a crime.

Journal of Research in Crime and Delinquency 2023, Vol. 60(4) 455–492