From Echo Chambers to Resonance Chambers: How Offline Political Events Enter and Are Amplified In Online Networks

Political hostility and ideological polarization permeate political debates on social media, but what is driving long-term developments in ideological polarization and political hostility? Prominent theories of social media argue that social media networks are best conceptualized as echo chambers, i.e., systems insulated from external input. Contrary to this view, we demonstrate that over the course of the 2020 election year in the US, all major ebbs and flows in political hostility on the social media platform Twitter were driven by external offline events. Importantly, these events were magnified for Twitter users within the most politically hostile and least ideologically diverse networks. Accordingly, social media networks are often best conceptualized as semi-open resonance chambers that are not insulated from external events but magnify them. We demonstrate that resonance chambers facilitate event-driven hostility via feedback loops that makes Twitter both more hostile and more ideologically polarized.