DeGroot-based opinion formation under a global steering mechanism

In this paper we investigate how interacting agents arrive to a consensus or a polarized state. More specifically, we study the opinion formation process under the effect of a global steering mechanism (GSM). We consider that the GSM aggregates agents' opinions at the network level and feeds back to them a form of global information. We propose the GSM-DeGroot model, a new two-layer agent-based opinion formation model that captures the coupled dynamics between agent-to-agent local interactions and the GSM's steering effect. This way, agents are subject to the effects of a DeGroot-like local opinion propagation, as well as to a wide variety of possible aggregated information that can affect their opinions, such as trending news feeds, press coverage, polls, elections, etc. The cornerstone feature of our model that, contrary to the standard DeGroot model, allows polarization to emerge, is the differential way in which agents react to the global information. We explore numerically the model dynamics to find regimes of qualitatively different behavior, using simulations on synthetic data. Moreover, we challenge our model by fitting it to the dynamics of real topics, related to protests, social movements, and the escalation of a long geopolitical conflict to a war, which attracted the public attention and were recorded on Twitter. Our experiments show that the proposed model holds explanatory power, as it evidently captures real opinion formation dynamics via a relatively small set of interpretable parameters.