Echo chambers revisited: The (overwhelming) sharing of in-group politicians, pundits and media on Twitter

Analyzing four years of data from a random sample of about 1.5 million Twitter users (and about 180,000 politically engaged users), we revisit the debate regarding the extent to which social media users live in political ``echo chambers'' with two new analytic approaches. First, we focus on the sharing of content from political elites, arguably the most influential and politically active actors, and estimate the extent to which ordinary users share messages from politicians, pundits, and news media of the same versus opposing ideology. Second, we examine the extent to which this sharing is annotated by users before it is shared (``quoted retweets'') and the tone of these annotations (e.g., do users share out-group content with negative commentary?). We find clear patterns indicative of echo-chambers: the politically engaged users analyzed share in-group messages from elites 14 times more frequently than out-group messages; and in the rare instances when out-group information is shared, a non-trivial amount of times it is accompanied by negative comments. These patterns emerge after accounting for how many in-group versus out-group elites a person follows, and are robust to the political interest of the user or extremity of the elite accounts, the topic of the tweet, and the type of political elite source of the original message. In line with previous research, we also find that this echo chamber is especially pronounced among conservative users, who are about twice as likely as liberals to share in-group vs out-group content. These findings have important implications for how we theorize and study online echo chambers.