Social Media, News Consumption, and Polarization: Evidence from a Field Experiment

Does the consumption of ideologically congruent news on social media exacerbate polarization? I estimate the effects of social media news exposure by conducting a large field experiment randomly offering participants subscriptions to conservative or liberal news outlets on Facebook. I collect data on the causal chain of media effects: subscriptions to outlets, exposure to news on Facebook, visits to online news sites, and sharing of posts, as well as changes in political opinions and attitudes. Four main findings emerge. First, random variation in exposure to news on social media substantially affects the slant of news sites that individuals visit. Second, exposure to counter-attitudinal news decreases negative attitudes toward the opposing political party. Third, in contrast to the effect on attitudes, I find no evidence that the political leanings of news outlets affect political opinions. Fourth, Facebook's algorithm is less likely to supply individuals with posts from -counter-attitudinal outlets, conditional on individuals subscribing to them. Together, the results suggest that social media algorithms may limit exposure to -counter-attitudinal news and thus increase polarization.

Automated summary

The study shows that exposure to news on social media affects the slant of news sites individuals visit, while exposure to counter-attitudinal news reduces negative attitudes toward opposing political parties. Although the political leanings of news outlets do not influence political opinions, Facebook's algorithm is less likely to supply individuals with posts from counter-attitudinal outlets.