Polarized information ecosystems can reorganize social networks via information cascades

Significance Many argue that partisan media coverage creates political polarization by pushing people’s opinions to extremes, but evidence is mixed. We instead propose that partisan media coverage can cause polarization by altering people’s social connections and reorganizing social networks along political lines. Using computational modeling and social media data, we explore how people may adjust their social ties to avoid the sharing behavior of friends who might be engaging with news from nonpreferred information sources. Our model suggests that polarization is driven to a large extent by unfollowing, which can gradually—and inadvertently—produce homogeneous online networks, known to reduce exposure to challenging information and encourage outgroup hostility. In this way, institutional polarization can reverberate through the networked mass public.