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Do social networks affect the spread of behavior?

Scientists have long thought that social networks, which features many distant connections, or “long ties,” produces large-scale changes most quickly. But in a new study, Damon Centola, an assistant professor at the MIT Sloan School of Management, has reached a different conclusion: Individuals are more likely to acquire new health practices while living in networks with dense clusters of connections — that is, when in close contact with people they already know well. Turns out dense networks are not as inefficient as first thought.

Researchers often regard these dense clusters of connections to be redundant when it comes to spreading information; networks featuring such clusters are considered less efficient than networks with a greater proportion of long ties. But getting people to change ingrained habits, Centola found, requires the extra reinforcement that comes from those redundancies. In other words, people need to hear a new idea multiple times before making a change.

Over to you Scientific America:

Diseases can spread quickly. Someone with a cold infects a few casual contacts, who in turn infect others. Ideas can also spread that way, along so-called random networks. But Damon Centola at MIT says that ideas and beliefs spread faster and more efficiently when they’re reinforced in clustered networks, with overlapping connections among the members.


Centola recruited more than 1,500 participants for what was billed as a Web-based health community. Each had an anonymous profile and was matched with health buddies. In one group, a minimal number of links connected the participants. The other group was denser, with redundant links.


In each group, a seed participant was planted with an idea: to register for an online health forum. Whenever a member registered, the member’s contacts got the message. Ultimately, 54 percent of the participants in the clustered network signed up, compared with only 38 percent in the random network. And the behavior spread about four times faster in the clustered groups. The study is in the journal Science. [http://bit.ly/96jPpc]


Centola thinks people are more swayed when they hear that multiple contacts are trying something new and that public health officials should take advantage of clustered networks to encourage people’s healthful behaviors.

I suspect that behavior adoption under uncertainty — when someone doesn’t know what to do — would be even higher. This is part of what cults use to recruit you. We’ve evolved to copy and mimic behaviors of those around us and this is most pronounced in uncertain situations. I wonder how much your work networks influence your behavior?

As with any study be careful extrapolating the results too far from what was actually tested.

Abstract: The Spread of Behavior in an Online Social Network Experiment

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.