Curation Bubbles: Domain Versus URL Level Analysis of Partisan News Sharing on Social Media

  • Empirical inquiries of political news consumption are typically based on analysis at the level of the news source: a given web domain can be assigned a partisanship score reflective of its relative tendency to be shared by Democrats or Republicans. This practical, tractable approach represents an important methodological advance which has allowed for large-scale empirical studies of how democratic citizens consume political information online. However, despite strong evidence that information sharing is dominated by in-group bias, previous work has also found that most users are exposed to information from a balanced variety of mainstream sources. Such conflicting findings around filter bubbles and echo chambers highlights the need to be able to estimate partisanship at the more fine-grained level of individual stories. It may be that individuals tend to consume politically homogeneous content which originates from a relatively heterogeneous collection of sources. Rather than never sharing stories associated with their political opponents, partisans may selectively share out-group content precisely when that information is favorable to them. Using a panel of 1.6 million Twitter users linked to administrative data, we test this dynamic by examining within-domain sharing patterns by user partisanship over time. Consistent with previous work, we find that, in aggregate, partisans do consume news from a variety of sources. However, we find notable story-level differences suggesting that, despite the heterogeneity of sources, the news curated from partisan's social networks contains politically homogeneous information. Our findings suggest that domain-level analyses of information sharing gives a false impression of exposure to politically diverse content, and raises new concerns regarding polarization in the consumption and sharing of digital media