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Political Polarization:
Uncertainty and the Neurobiology of Why We’re So Divided

While many essays have addressed the social events and psychological traits that drive polarized thinking, the neural underpinnings of uncertainty and polarization are largely unknown. We know the brain processes information and makes decisions, but we know little about how politically polarized information is encoded and even less about how attitudes about uncertainty influence that processing. Why is it important? Uncertainty may be seen as a threat, which moves individuals toward certain positions on the ends of ideological spectrums when considering political candidates1 and policy positions.2

A recent study in the Proceedings of the National Academy of Sciences3 (PNAS) took a fresh look at the neuroscience of polarization. “Neural synchrony,” as defined in this study, is the tendency of two individuals’ brains to share a similar pattern of activity when receiving the same information. Dr. FeldmanHall and her team learned that politically like-minded people have synchronized brain activity when watching politically polarizing video clips and that this activity matches up to an even greater degree between people who find it difficult to tolerate uncertainty. The closest matched activity was observed in the orbitofrontal cortex (OFC) and the anterior insula (AI), brain regions that control value judgments and socioemotional activity, respectively.

In the study, self-identified liberal and conservative participants were asked to report their political ideology on a spectrum ranging from “extremely liberal” to “extremely conservative.” Then, while they were shown an incendiary video clip from the 2016 vice-presidential debate between Tim Kaine and Mike Pence, their brain activity was measured using an fMRI. Self-reported ideology was confirmed by agreement with statements from the video. These results were compared against responses to a nature video and a neutrally worded news segment on abortion.

Polarized Minds Think Alike

The first finding of this study demonstrated that pairs of participants with similar ideologies (among both conservatives and liberals) showed neural synchrony when viewing the debate clip, no similarity when viewing the nature video, and activity localized to only one brain region during the news segment on abortion. These data suggest that “like-minded” individuals have synchronized brain activity when receiving polarized information, a persistent finding among both liberals and conservatives.

Uncertainty Makes Polarized Minds More Synchronized

Participants also took a validated assessment to measure Intolerance of Uncertainty (IUS). Individuals with strong IUS and left or right political ideology exhibited enhanced neural synchrony in areas of the brain associated with values, emotion, and visual processing. They showed even more similarity in their imaging patterns while watching the political debate video clip than when watching a nature video or a neutrally worded news segment. This, too, was seen among both conservatives and liberals. While previous studies have outlined structural and psychological differences between liberals and conservatives, this study revealed shared neurological processing that underlies polarization and demonstrates how it is exacerbated by perceived uncertainty.

As technology continues to grow and change rapidly, the level of uncertainty in the world is not likely to wane. FeldmanHall’s results suggest that increasing uncertainty could further divide society. A new quarterly measuring system, the World Uncertainty Index, has demonstrated an upward trend. This index captures economic and political events over the past 60 years in 143 countries, including Brexit, the occupation and withdrawal from Afghanistan, Korean tensions, etc. The index utilizes text mining for the word “uncertainty” in country-specific policies gathered by the Economist Intelligence Unit.

Overcoming Polarization and Uncertainty

Given that polarization can contribute to democratic instability, distrust of scientific evidence, and support for authoritarianism, the level of uncertainty we might experience is, well… uncertain. Thus, it might be helpful to find ways to increase our tolerance for it. Not only does intolerance of uncertainty affect interactions between political groups, but it has also been associated with various anxiety-based disorders. The good news is that evidence has begun to surface from randomized clinical trials that Intolerance to Uncertainty Therapy might improve anxiety symptoms. If uncertainty fuels divisiveness, perhaps strengthening our ability to live with uncertainty can bring us together.


Understanding the psychological and biological underpinnings of political polarization is only the first step in working towards restabilizing our deeply divided society. In Dr. FeldmanHall’s study, the topic of abortion alone did not trigger ideology-synced brain activity, suggesting neutrally worded information does not induce polarization. This distinction indicates a need to consider how we receive information. The current media monetization model is based on generating revenue through attention-encouraging, often divisive outrage, which, according to this study, would activate polarized neural synchronicity. In response to this problem, media organizations that seek to present more inclusive sources of information have been emerging. Outlets such as AllSides, Tangle, and Readocracy fight media bias and minimize polarization. Each site takes a different approach to foster a greater diversity of viewpoints, hoping to help readers gain a more holistic view of a given issue.

Increasing our tolerance for uncertainty, reducing black-and-white thinking, being aware of media bias, and promoting a more neutral presentation of news and varying sides of a news story might help us heal division and neutralize political polarization exacerbated by the ever-changing circumstances of the 21st century. END

About the Author

Natasha Mott is a neuroscientist, podcaster, and writing fellow with the Heterodox Academy. Known online as Theory_Gang, her commentary covers science, culture, and philosophy in various formats from memes, videos, and essays. She has worked in biotechnology, democracy reform, software, game development, and is currently working on her first book, a daily dialectic on science and existentialism.

  1. McGraw, K. M., Hasecke, E., & Conger, K. (2003). Ambivalence, Uncertainty, and Processes of Candidate Evaluation. Political Psychology, 24(3), 421–448.
  2. Haas, I. J., Baker, M. N., & Gonzalez, F. J. (2021). Political Uncertainty Moderates Neural Evaluation of Incongruent Policy Positions. Philosophical Transactions of the Royal Society B: Biological Sciences, 376(1822), 20200138.
  3. Baar, J. M. van, Halpern, D. J., & FeldmanHall, O. (2021). Intolerance of Uncertainty Modulates Brain-to-Brain Synchrony During Politically Polarized Perception. Proceedings of the National Academy of Sciences, 118(20).

This article was published on March 4, 2023.

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