Complex contagions and the weakness of long ties
A paper by Damon Centola and Michael Macy
Extract from the paper:
As Granovetter puts it (1973, p. 1366), “whatever is to be diffused can reach a larger number of people, and traverse a greater social distance, when passed through weak ties rather than strong.” This insight has become one of the most widely cited and influential contributions of sociology to the advancement of knowledge across many disciplines, from epidemiology to computer science.
Nevertheless, the central claim of this study is the need to circumscribe carefully the scope of Granovetter’s claim. Specifically, while weak ties facilitate diffusion of contagions like job information or diseases that spread through simple contact, this is not true for “whatever is to be diffused.” Many collective behaviors also spread through social contact, but when these behaviors are costly, risky, or controversial, the willingness to participate may require independent affirmation or reinforcement from multiple sources. We call these “complex contagions” because successful transmission depends upon interaction with multiple carriers.