Is Congress More Polarized than the Public Because it is More Informed than the Public?

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Principal investigator:

Benjamin Lauderdale

London School of Economics and Political Science



Sample size: 3600

Field period: 5/10/2010-6/30/2010


Recent studies of the U.S. Congress have demonstrated a substantial difference in the level of partisan polarization displayed by legislators’ votes and that shown in citizens’ survey responses about those votes. But perhaps public polarization would increase if citizens were more attentive to political debates in Congress? Using techniques that match on natural variation in citizens’ levels of political information, I show that citizens who are informed about the partisan alignment of issues have a preference distribution similar to that of Congress, even after the sample is re-weighted to resemble the entire public in their political, social, and demographic characteristics. In contrast, using a survey experiment, I show that cue and argument treatments only partially reduce the discrepancy between the views expressed by the public and the voting behavior of Congress on the same issues. Both experimental and observational studies have significant limitations for measuring counterfactuals involving public opinion, and so our understanding of the polarization gap remains unfortunately limited.


Does public polarization, as measured by profiles of issue positions, increase when citizens are exposed to information about elite positions and arguments.

Experimental Manipulations

2x2 design. One treatment was information on the party breakdown of the House vote on a bill. The second treatment was information about elite arguments for and against the bill.


Self-reported positions on six issues voted on by the U.S. House of Representatives in 2009.

Summary of Results

U.S. citizens who know which party takes which side of high profile legislative issues are just as polarized as the U.S. Congress on those issues. The fact that most Americans are less polarized seems to be partially due to the fact that they are not paying attention to the lively partisan debate that tends to accompany such issues. However, differences between results based on analyzing cross-sectional variation in information levels and experimental provision of information leave substantial uncertainty as to the exact shape of the U.S. public’s preferences about roll-call votes, under the counterfactual in which all Americans were as attentive to partisan debates about issues as their most informed fellow citizens. Identifying the preferences that citizens would hold if they were all highly attentive to political debate requires identifying the causal effects of treatments that are too large, and too ill-defined, to be the subject of an experiment. The feasible treatments implemented in this study are a limited remediation of citizens' limited information about politics. Because of this identification problem, we cannot say exactly how close the U.S. Congress comes to the preference distribution that the American public would have, were all citizens more attentive to politics. Nonetheless, we can say that these distributions of preference are at least somewhat closer than those we actually observe in a political world where most citizens are paying little attention to politics.


Lauderdale, Benjamin E. (2013).“Does Inattention to Political Debate Explain the Polarization Gap Between the U.S. Congress and Public?” (2013). Public Opinion Quarterly. 77. pp. 2-23.