Tipping points in changing social conventions.

How can we explain the rapid rise of the Nazis in 1930s Germany or the rapid acceptance of gay marriage in the United States? Centola et al. approach this question by doing both modeling and experiments illustrating how a motivated minority can change a social convention. They

...study a system of coordination in which a minority group of actors attempt to disrupt an established equilibrium behavior. In both our theoretical framework and the empirical setting, we adopt the canonical approach of using coordination on a naming convention as a general model for conventional behavior. Our experimental approach is designed to test a broad range of theoretical predictions derived from the existing literature on critical mass dynamics in social conventions.

Here is the Science Magazine summary followed by the abstract:

Once a population has converged on a consensus, how can a group with a minority viewpoint overturn it? Theoretical models have emphasized tipping points, whereby a sufficiently large minority can change the societal norm. Centola et al. devised a system to study this in controlled experiments. Groups of people who had achieved a consensus about the name of a person shown in a picture were individually exposed to a confederate who promoted a different name. The only incentive was to coordinate. When the number of confederates was roughly 25% of the group, the opinion of the majority could be tipped to that of the minority.

Abstract

Theoretical models of critical mass have shown how minority groups can initiate social change dynamics in the emergence of new social conventions. Here, we study an artificial system of social conventions in which human subjects interact to establish a new coordination equilibrium. The findings provide direct empirical demonstration of the existence of a tipping point in the dynamics of changing social conventions. When minority groups reached the critical mass—that is, the critical group size for initiating social change—they were consistently able to overturn the established behavior. The size of the required critical mass is expected to vary based on theoretically identifiable features of a social setting. Our results show that the theoretically predicted dynamics of critical mass do in fact emerge as expected within an empirical system of social coordination.