Large Structures Seminar: Gerardo Iñiguez

Adoption of innovations, products or online services is commonly interpreted as a spreading process driven largely by social influence and mediated by the needs and capacities of individuals. In order to model this process one usually introduces behavioral threshold mechanisms, which can give rise to the evolution of system-wide adoption (known as a global cascade) if the system satisfies a set of conditions. However, these models do not address temporal aspects of the emerging cascades, which in real systems may evolve through various pathways ranging from slow to rapid patterns. Here we propose a way to fill this gap through the analysis and modeling of online adoption in the world’s largest voice over internet service, the social network of Skype. We measure the distribution of behavioral thresholds and other structural and dynamical properties of the worldwide adoption process. By incorporating the observed features into a dynamical threshold model, we show that the spreading of online services is induced by a constant flow of spontaneous adoptions and constrained by the fraction of non-adopters in the network. We observe that the structure of real-world adoption clusters is radically different from previous theoretical expectations, since vulnerable adoptions (induced by a single adopting neighbor) appear to be important only locally, while spontaneous adoptions and the involvement of more resistant individuals are responsible for the global emergence of social spreading phenomena.