The impact of partisan news exposure on American political opinion and behavior: Evidence from the 2008 presidential election

Do partisan media influence the American public\u27s political opinions and behaviors? This question is the focal point of a lively debate triggered by the proliferation of partisan media in the U.S. over the past few decades. Yet despite widespread interest in questions of partisan media influence, there is surprisingly sparse empirical evidence on which to base any answers. Using panel data collected during the 2008 presidential election, this dissertation provides strong evidence that partisan news exposure has important consequences for American political behavior. Politically likeminded news is shown to be a significant influence on vote choice, not only modestly reinforcing initial preferences but also motivating changes in vote choice over time. Likeminded news also spurs higher levels of campaign activity during the campaign, though it does not appear to mobilize higher turnout. There is also strong evidence that likeminded news enhances consistency in political thinking, both increasing ideological constraint among citizens\u27 issue positions and encouraging them to amass an internally consistent set of candidate considerations that uniformly supports their initial vote preference. Moreover, partisan news slanted away from citizens\u27 own views is shown to be a potent force working in the opposite direction of likeminded news. Exposure to such dissonant news significantly boosts the odds of defection, encourages citizens to develop more internally conflicted candidate considerations, and depresses levels of campaign activity. This robust evidence of partisan news effects sharply contrasts with the sporadic and weak influence that exposure to traditional (i.e., politically neutral) news is found to exert. The implications of these findings are discussed within the context of an ongoing normative discourse about the news media\u27s role in American democracy. The observed effects of partisan news can be viewed as undermining key goals of a deliberative and participatory democracy. Alternatively, the effects can be understood as evidence that partisan news offsets some of neutral news\u27 weaknesses, filling some of the media\u27s previously neglected roles in helping citizens perform their democratic duties. This dissertation proposes that the diverse needs of a democratic public may be best met by the current heterogeneous mix of partisan news and neutral news sources