SSS 2010-09-03（在线收听）

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.

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.

Thanks for the minute.For scientific American's 60-Second Science.I' Cynthia Graber