Imitation and the dynamics of norms

In the model, each person in a large population has a probability of adhering to some behavior, such as a social norm. At random, people observe each other and adjust their adherence probabilities in an imitative direction. In a main case of the model, there are high and low stable equilibria; the distribution of adherence probabilities evolves upward or downward, depending on initial conditions, until the population is in strong conformity with the norm or in strong rejection of the norm. In other cases of the model, there is a single stable equilibrium. Equilibria may be fragile. Small differences in initial conditions may lead otherwise similar populations to opposite equilibria, and social shocks may tip a population from one equilibrium to another or change the number of equilibria.  2000 Elsevier Science B.V. All rights reserved.