Diffusion in Social Networks: New Theory and Experiments
Abstract: The strength of weak ties is that they tend to be long – they connect socially distant locations. Research on “small worlds” shows that these long ties can dramatically reduce the “degrees of separation” of a social network, thereby allowing ideas and behaviors to rapidly diffuse. However, I show that the opposite can also be true. Increasing the frequency of long ties in a clustered social network can also inhibit the diffusion of collective behavior across a population. For health related behaviors that require strong social reinforcement, such as dieting, exercising, smoking cessation, or even condom use, successful diffusion may depend primarily on the width of bridges between otherwise distant locations, not just their length. I present formal and computational results that demonstrate these findings, and then present an experimental test of the effects of social network topology on the diffusion of health behavior.
