Clustered Networks Spread Behavior Change Faster

Unlike infectious diseases and news, behavior change spreads faster through online networks that have many close connections instead of many distant ties. Redundancy is key, as people are more likely to engage in a behavior if they see many others doing it.

“There has been a lot of theory about the difference between information and behavior spreading,” said economic sociologist Damon Centola of the Massachusetts Institute of Technology, author of the study published Sept. 3 in Science. “We’ve assumed that they are the same, but you can imagine that behavior is not really like that, that you need to be convinced.”

The research has important implications for people designing online communities intended to change or maintain a behavior, like weight watchers or online health communities, Centola said.

To do the experiment, he created an internet-based health community and invited people already participating in other online health forums to join. Over 1,500 people signed up to participate, and they were placed anonymously in one of two different kinds of networks: a random network with many distant ties (above left), or a clustered network with many overlapping connections (above right).

Users in both networks had the same number of assigned “health buddies.” They couldn’t contact their buddies directly, but they could see how their buddies rated content on the site, and could receive e-mails informing them of their buddies activities. Centola said he deliberately didn’t pay the volunteers, so they would participate out of legitimate interest in the site’s content.

In six different trials over a period a few weeks, Centola seeded the site with information about an online health forum and tracked people as they signed up and participated.