An analysis of 100 million installations of applications — or 'apps' — on the popular social-networking site Facebook demonstrates that online social influences have an on–off pattern. Social pressure pushed apps that were installed by more than about 55 users per day to heights of popularity. Below this tipping point, users seemed to install or not install apps regardless of what their friends or others in the network were doing, suggesting that there was no social influence.

Felix Reed-Tsochas and Jukka-Pekka Onnela of the University of Oxford, UK, identified the behavioural threshold, which has never been seen in the offline world, by combing through data from 2,705 apps. The researchers consider it to be an inherent property of this particular networking systems and expect it to be observed in other online networks.

Proc. Natl Acad. Sci. USA 10.1073/pnas.0914572107 (2010)