The Rippling effect of social influence via phone communication network

Phenomena such as “small-world” and “six degrees of separation” reveal the connectivity between individuals that are seemingly unrelated in the society. Beyond merely connectivity, it has been shown in recent years that social contagion exists in online interactions. Along this line of investigation, we are interested in the subtle and invisible social influence on real-world behavior across offline communication networks. In particular, we study how social influence propagates and triggers behavioral change, and how such effect expands deeply across the social network in a way similar to the physical phenomenon of ripples across the water. To this end, we analyze a large-scale one-month international event in Andorra using nation-wide mobile phone data, and investigate the change in the likelihood of attending the event for people that have been influenced by and are of different social distances from the attendees. Our results suggest that social influence exhibits the ripple effect, decaying across social distances from the source but persisting up to six degrees of separation in the social network. We further show that such influence decays as communication delay increases and communication intensity decreases, and that it is stronger among people who are more explorative geographically. Our findings may have important implications in a number of domains, such as marketing, public health, and social mobilizations