Harvard Medical School, Harvard University, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 2010 Oct 26;107(43):18375-80. doi: 10.1073/pnas.0914572107. Epub 2010 Oct 11.
Social influence drives both offline and online human behavior. It pervades cultural markets, and manifests itself in the adoption of scientific and technical innovations as well as the spread of social practices. Prior empirical work on the diffusion of innovations in spatial regions or social networks has largely focused on the spread of one particular technology among a subset of all potential adopters. Here we choose an online context that allows us to study social influence processes by tracking the popularity of a complete set of applications installed by the user population of a social networking site, thus capturing the behavior of all individuals who can influence each other in this context. By extending standard fluctuation scaling methods, we analyze the collective behavior induced by 100 million application installations, and show that two distinct regimes of behavior emerge in the system. Once applications cross a particular threshold of popularity, social influence processes induce highly correlated adoption behavior among the users, which propels some of the applications to extraordinary levels of popularity. Below this threshold, the collective effect of social influence appears to vanish almost entirely, in a manner that has not been observed in the offline world. Our results demonstrate that even when external signals are absent, social influence can spontaneously assume an on-off nature in a digital environment. It remains to be seen whether a similar outcome could be observed in the offline world if equivalent experimental conditions could be replicated.
社会影响力驱动着线下和线上的人类行为。它渗透到文化市场中，体现在科学技术创新的采用以及社会习俗的传播。先前关于空间区域或社交网络中创新扩散的实证研究主要集中在特定技术在所有潜在采用者子集之间的传播。在这里，我们选择了一个在线环境，通过跟踪社交网站用户群体安装的一整套应用程序的流行度，来研究社会影响过程，从而捕捉到了在这种情况下相互影响的所有个体的行为。通过扩展标准的波动标度方法，我们分析了由 1 亿次应用程序安装所引发的集体行为，并表明系统中出现了两种不同的行为模式。一旦应用程序的流行度超过了特定的阈值，社会影响过程就会在用户之间引发高度相关的采用行为，从而推动一些应用程序达到非凡的流行度。在这个阈值以下，社会影响的集体效应似乎几乎完全消失了，这种现象在离线世界中尚未观察到。我们的研究结果表明，即使在没有外部信号的情况下，社会影响力也可以在数字环境中自发地呈现出开-关的性质。如果能够复制等效的实验条件，是否会在离线世界中观察到类似的结果，还有待观察。
