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First published 20 July 2015

The Universality of Peer-Influence in Social Networks

Flávio L. Pinheiro, Marta D. Santos, Francisco C. Santos, Jorge M. Pacheco


Social networks pervade our everyday lives: we interact, influence and are influenced by our friends and acquaintances. The recent availability of large amounts of data on social networks has fostered quantitative analyses of the distribution of information on them, including behavioural traits and fads. In particular, recent studies have shown the existence of positive correlations in the distribution of traits in a social network composed by the participants of the Framingham Heart study Christakis and Fowler (2007); Fowler and Christakis (2008). Surprisingly the peer-influence patterns found among the participants went beyond the influence of their closest peers, but also their friends’ friends,up to three degrees of influence.

In Pinheiro et al. (2014) we show how similar patterns of correlations between peers emerge in networked populations through standard models (yet reflecting intrinsically different mechanisms) of information spreading such as the Voter’s Model, the SIR epidemic model (see Fig. 1) and Evolutionary Game Theory models of cooperation. We argue that empirically observed patterns of correlation among peers emerge naturally from a wide range of dynamical processes, being essentially independent of the type of information, on how it spreads, and even on the class of underlying network that inter-connects individuals. Finally, we show that the sparser and clustered the network, the more far-reaching the influence of each individual will be.