How rumors spread

How rumors spread. The events of the Arab Spring and other uprisings and protests over the past year have dramatically demonstrated the ability of social media to widely disseminate information and trigger collective action. Analyzing complex interaction networks, Hernán Makse and colleagues showed in 2010 that the people most influential in the spreading of an idea—or an infectious disease, for that matter—are not those who know the most other people, but rather those at a well-defined core of the network. Now, Javier Borge-Holthoefer and Yamir Moreno of Spain’s University of Zaragoza have analyzed rumor-spreading models, which may be more appropriate for describing social contagion. In such models, a person may be an ignorant, unaware of some piece of information; a spreader, aware and willing to transmit it; or a stifler, knowledgeable but uninterested in sharing further. An ignorant contacted by a spreader can become another spreader, while...