Party Animals? Extreme Partisan Polarization and Dehumanization


The affective, identity based, and often negative nature of partisan polarization in the United States has been a subject of much scholarly attention. Applying insights from recent work in social psychology, we employ three novel large-N, broadly representative online surveys, fielded over the course of 4 years, across two presidential administrations, to examine the extent to which this brand of polarization features a willingness to apply dehumanizing metaphors to out-partisans. We begin by looking at two different measures of dehumanization (one subtle and one more direct). This uncovers striking, consistent observational evidence that many partisans dehumanize members of the opposing party. We examine the relationship between dehumanization and other key partisan intensity measures, finding that it is most closely related to extreme affective polarization. We also show that dehumanization “predicts” partisan motivated reasoning and is correlated with respondent worldview. Finally, we present a survey experiment offering causal leverage to examine openness to dehumanization in the processing of new information about misdeeds by in- and out-partisans. Participants were exposed to identical information about a melee at a gathering, with the partisanship of those involved randomly assigned. We find pronounced willingness by both Democrats and Republicans to dehumanize members of the out-party. These findings shed considerable light on the nature and depth of modern partisan polarization.

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  1. 1.

    While electoral politics in the United States establishes political winners and losers, neither party has recently held a consistent, unassailable grip on all branches and levels of government. Both parties are well-funded and while one party may lose political power temporarily, each tends to ascend to power on a regular basis. Political parties exist not in a static hierarchy but a dynamic system where political power shifts back and forth between them.

  2. 2.

    YouGov uses block randomization to maximize representativeness. For the SSI sample, we imposed population based quotas for joint distributions of race and education to maximize broad representativeness. This sample is reasonably representative of the national population, although it contains comparatively more women and fewer middle-aged people than the national population. The distributions of demographic variables can be found in the Appendix.

  3. 3.

    We also plot the relationship between blatant dehumanization and each individual party feeling thermometer. It does not appear that the result is driven by inparty or outparty affect alone - both feeling thermometers have similar relationships with blatant dehumanization. See Fig. VI in the Online Appendix.

  4. 4.

    In keeping with the suggestions of Miratrix et al. (2018) the analyses presented here do not use sampling weights. Distributions of sample demographics including age, race, gender, household income, and partisanship can be found in the Appendix.

  5. 5.

    We also included an ambiguous condition that did not specify whether the perpetrator group was composed of Republicans or Democrats. For interpretational clarity, we exclude this condition from the focal analysis. Based on recent work, we suspect that although political party was not explicitly mentioned in this ambiguous condition, many participants might infer that their rival political party committed the misdeed.

  6. 6.

    It is possible that some respondents may make assumptions/inferences regarding the race of the partisans involved, specifically that Democrats are more likely non-white. In fact, Ahler and Sood (2018) show that voters overestimate the percentage of Democrats who are black. Having said that, we made a conscious choice in the design of this experiment to not guide respondents to imagine white Democrats or Republicans, either through the text or image. This is because we view racial associations as part of the admittedly bundled party label treatments.


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We thank Doug Ahler, Steve Ansolabehere, Vin Arceneaux, Larry Bartels, Henry Brady, Erin Cassese, Jack Citrin, Maggie Deichert, Stephen Goggin, John Henderson, Nathan Kalmoe, Cindy Kam, David Karol, Lily Mason, Steve Nicholson, David Nickerson, Eric Schickler, Gaurav Sood, and Rob Van Houweling for helpful feedback. This research was made possible by generous funding from the University of California, Merced, and the Vanderbilt University Center for the Study of Democratic Institutions, and was supported by National Science Foundation Awards #1559125 and #1756447. We also thank the Vanderbilt Research on Individuals, Politics and Society Lab. Replication and online supplementary materials are available here:

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Correspondence to Alexander G. Theodoridis.

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Martherus, J.L., Martinez, A.G., Piff, P.K. et al. Party Animals? Extreme Partisan Polarization and Dehumanization. Polit Behav (2019).

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  • Dehumanization
  • Party identity
  • Partisanship
  • Affective polarization