OB Research Seminar - Minhua Yan, Toulouse School of Economics, Institute for Advanced Study

Social norms are unwritten codes that guide our behavior and interactions. They play a key role in shaping human psychology and cultural variation. My research explores how norms influence individual actions and what factors shape their content and evolution, using mathematical modeling, fieldwork, and online surveys. In this talk, I will present a mathematical model and a field study. The model challenges the idea that arbitrary or harmful norms can persist solely due to social pressure. It shows that norms with continuously varying options cannot be maintained at an equilibrium different from what is ecologically and psychologically optimal. This suggests norms may adapt more easily than previously thought. The field study on the Derung people, small-scale horticulturalists in Yunnan, China, finds that they adhere to a cooperative farming harvest division norm although they know that it brings lower ecological payoffs and deviating from it incurs no social costs. Instead of payoff considerations, Derung farmers' normative behavior is driven by their desire to follow tradition and common practice. Rare social costs arise because deviations may cue that the farmer is selfish and does not value their co-farming partner. These findings suggest that norms can persist without costly enforcement.