The Spread of Behavior in an Online Social Network Experiment

Join the Club An important question for policy-makers is how to communicate information (for example, about public health interventions) and promote behavior change most effectively across a population. The structure of a social network can dramatically affect the diffusion of behavior through a population. Centola (p. 1194) examined whether the number of individuals choosing to register for a health forum could be influenced by an artificially constructed network of neighbors that were signed up for the forum. The behavior spread more readily on clustered networks than on random, poorly clustered ones. Certain types of behavior within human systems are thus more likely to spread if people are exposed to many other people who have already adopted the behavior (for example, in the circumstances where your friends know each other, as well as yourself). An online experiment shows how network structure affects the spread of health behavior. How do social networks affect the spread of behavior? A popular hypothesis states that networks with many clustered ties and a high degree of separation will be less effective for behavioral diffusion than networks in which locally redundant ties are rewired to provide shortcuts across the social space. A competing hypothesis argues that when behaviors require social reinforcement, a network with more clustering may be more advantageous, even if the network as a whole has a larger diameter. I investigated the effects of network structure on diffusion by studying the spread of health behavior through artificially structured online communities. Individual adoption was much more likely when participants received social reinforcement from multiple neighbors in the social network. The behavior spread farther and faster across clustered-lattice networks than across corresponding random networks.