Infection patterns in simple and complex contagion processes on networks

TL;DR

This paper investigates how infection patterns vary across different contagion models on networks, revealing robustness in simple contagion and complex dependencies in complex and threshold-based contagions.

Contribution

It systematically compares infection patterns across simple, complex, and threshold contagion models, highlighting their differing sensitivities to parameters.

Findings

Simple contagion patterns are highly robust across models and parameters.

Complex contagion patterns depend on the interplay of pairwise and group interactions.

Threshold models show significant changes in spreading paths with slight parameter variations.

Abstract

Contagion processes, representing the spread of infectious diseases, information, or social behaviors, are often schematized as taking place on networks, which encode for instance the interactions between individuals. The impact of the network structure on spreading process has been widely investigated, but not the reverse question: do different processes unfolding on a given network lead to different infection patterns? How do the infection patterns depend on a model's parameters or on the nature of the contagion processes? Here we address this issue by investigating the infection patterns for a variety of models. In simple contagion processes, where contagion events involve one connection at a time, we find that the infection patterns are extremely robust across models and parameters. In complex contagion models instead, in which multiple interactions are needed for a contagion event, non-trivial dependencies on models parameters emerge, as the infection pattern depends on the interplay between pairwise and group contagions. In models involving threshold mechanisms moreover, slight parameter changes can significantly impact the spreading paths. Our results show that it is possible to study crucial features of a spread from schematized models, and inform us on the variations between spreading patterns in processes of different nature.