Title: The Conditional Effects of Media Tone on Public Opinion Authors: Amber Boydstun – University of California, Davis Dallas Card – Carnegie Mellon University Noah Smith – University of Washington Abstract: Past research has established that when a policy issue is covered in the media, the tone of the coverage (positive or negative) can affect citizens’ perceptions of the issue. Yet no prior research has examined whether the effect of media tone on public attitudes depends on other variables. We hypothesize that there is a positive conditional relationship between the effects of media tone on public opinion and the degree to which there is a single frame that dominates one side of the policy discussion. We test this hypothesis in the case of U.S. newspaper coverage to three policy issues—immigration, same-sex marriage, and gun control—1990 to 2012. We use manual coding linked with computational modeling, tracking both tone (pro/anti/neutral) and emphasis frames (e.g., morality, economic). Using time series analysis, we test whether media tone co-varies with public opinion (measured using Stimson’s policy mood measure) conditional on frame dominance. Our study adds to the fields of political communication and public opinion, and also marks an advance in computational text analysis methods.