Echo Chambers and Partisan Polarization : Evidence from the 2016 Presidential Campaign

Where do partisans get their election news and does this influence their candidate assessments? We track web browsing behavior among a national sample during the 2016 presidential campaign and merge these data with a panel survey. We find that election news exposure is polarized; partisans gravitate to "echo chambers," sources disproportionately read by co-partisans. We document levels of partisan selective exposure two to three times higher than prior studies. However, one-sided news consumption did not exacerbate polarization in candidate evaluation. We speculate this exposure failed to move attitudes either because partisans’ ill will toward their political opponents had already reached high levels at the outset of the study, or because of modest differences in the partisan slant of the content offered by the majority of news sources. Audience segregation appears attributable less to diverging perspectives, and more to the perceptions of partisans—particularly Republicans—that non-partisan news outlets are biased against them. *The authors thank the Bill Lane Center for the American West and the Hoover Institution for their generous financial support without which this study would not have been possible. They also thank Matthew Gentzkow, Jens Hainmueller, and Jesse Shapiro for their comments on an earlier draft. Fifty years ago, Americans’ held generally centrist political views and their feelings toward party opponents, while lukewarm, were not especially harsh (Iyengar, Sood, and Lelkes, 2012; Haidt and Hetherington, 2012). Party politics did not intrude into interpersonal relations; marriage across party lines occurred frequently (Jennings and Niemi, 1974; Jennings and Niemi, 1981; Jennings, Stoker, and Bowers, 2009). During this era of weak polarization, there was a captive audience for news. Three major news outlets— the evening newscasts broadcast by ABC, CBS, and NBC—attracted a combined audience that exceeded eighty million daily viewers (see Iyengar, 2015). The television networks provided a non-partisan, point-counterpoint perspective on the news. Since their newscasts were nearly identical in content, exposure to the world of public affairs was a uniform—and unifying—experience for voters of all political stripes. That was the state of affairs in 1970. Forty years later, things had changed dramatically. The parties diverged ideologically, although the centrifugal movement was more apparent at the elite rather than mass level (for evidence of elite polarization, see McCarty, Poole, and Rosenthal, 2006; Stonecash, Brewer, and Mariani, 2003; the ongoing debate over ideological polarization within the mass public is summarized in Abramowitz and Saunders, 2008; Fiorina and Abrams, 2009). The rhetoric of candidates and elected officials turned more acrimonious, with attacks on the opposition becoming the dominant form of political speech (Geer, 2010; Grimmer and King, 2011; Fowler and Ridout, 2013). Legislative gridlock and policy stalemate occurred on a regular basis (Mann and Ornstein, 2015). At the level of the electorate, beginning in the mid-1980s, Democrats and Republicans increasingly offered harsh evaluations of opposing party candidates and crude stereotypes of opposing party supporters (Iyengar, Lelkes, and Sood, 2012). Party affiliation had become a sufficiently intense form of social identity to serve as a litmus test for personal values and world view (Mason, 2014; Levendusky, 2009). By 2015, marriage and close personal relations across party lines was a rarity (Huber and Malhotra, 2017; Iyengar, Konitzer, and Tedin, 2017). Partisans increasingly distrusted and disassociated themselves from supporters of the opposing party (Iyengar and Westwood, 2015; Westwood