Local cascades induced global contagion: How heterogeneous thresholds, exogenous effects, and unconcerned behaviour govern online adoption spreading

TL;DR

This paper investigates how heterogeneous individual thresholds, spontaneous adoption, and unconcerned behavior influence the dynamics and pathways of online adoption spreading, using empirical data from Skype to enhance existing contagion models.

Contribution

It introduces a model incorporating temporal dynamics, heterogeneous thresholds, and spontaneous adopters, providing new insights into real-world online adoption processes.

Findings

Heterogeneous thresholds are independent of user connectivity.

Real-world adoption clusters differ from traditional models, emphasizing local vulnerability.

Spontaneous adopters and unconcerned individuals drive global spreading.

Abstract

Adoption of innovations, products or online services is commonly interpreted as a spreading process driven to large extent by social influence and conditioned by the needs and capacities of individuals. To model this process one usually introduces behavioural threshold mechanisms, which can give rise to the evolution of global cascades 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 fill this gap through the analysis and modelling of product adoption in the world's largest voice over internet service, the social network of Skype. We provide empirical evidence about the heterogeneous distribution of fractional behavioural thresholds, which appears to be independent of the degree of adopting egos. We show that the structure of real-world adoption clusters is radically different from previous theoretical expectations, since vulnerable adoptions --induced by a single adopting neighbour-- appear to be important only locally, while spontaneous adopters arriving at a constant rate and the involvement of unconcerned individuals govern the global emergence of social spreading.