Professors Christoph Riedl and David Lazer have been recognized with the 2026 James S. Coleman Award for Outstanding Article from the American Sociological Association (ASA) Section on Decision-Making, Social Networks, and Society.
This annual award recognizes pioneering scholarship in decision-making, social networks, and the broader traditions of analytical and computational sociology, and it's being awarded to the NetSI team and first author Jaemin Lee—Assistant Professor at the Chinese University of Hong Kong and formerly a Postdoctoral Research Associate at the Network Science Institute—for the research article “Complex Contagion in Social Networks: Causal Evidence from a Country-Scale Field Experiment.” published this year in Sociological Science.
This study provides rare experimental evidence for "complex contagion"—the idea that people are more likely to adopt a behavior when they receive reinforcing signals from multiple friends, rather than just one. To test this, researchers ran a large-scale field experiment across an entire country, randomly assigning people to be encouraged by either one or two friends to share a mobile data coupon. This random assignment let them isolate the real causal effect of multiple social connections pushing the same behavior. Using several different analytical approaches, including a novel computational method for calculating precise statistical results, the study found strong support for complex contagion: rather than each friend's influence acting independently, multiple friends' encouragement reinforced and amplified each other, making people significantly more likely to act. The researchers also found that how embedded someone is in their social network—essentially how interconnected their friend group is—shapes how powerful this reinforcement effect turns out to be. Overall, the study offers rare, real-world proof that social behaviors can spread not just through simple one-to-one influence, but through a more powerful process where multiple social signals combine to push people toward action.
