The Psychological Roots of Political Polarization

How should we study the things that most divide us?

Posted Oct 09, 2019

By Jeroen van Baar & Oriel FeldmanHall

Political polarization dominates the global news today. Take the debate on climate change. Sixteen-year-old climate activist Greta Thunberg recently gave an emotional speech at the U.N. General Assembly calling for immediate climate action. Liberals around the world sent out enthusiastic messages of support; conservatives, in turn, barraged the liberals for supposedly using a child with Autism Spectrum Disorder to advance their political agenda. When President Donald Trump tweeted an ironic dig about Thunberg, liberals were disgusted by his response. Within minutes, the topic of conversation had shifted from the core of the matter—climate change—to partisan mudslinging and fear mongering.

How did our political world become so polarized? This is a question on the mind of many psychologists today. And as with any scientific question, there are multiple approaches to answering it, each with its own strengths and weaknesses.

The Individual Differences Approach

One increasingly popular approach focuses on individual differences—or the stable psychological differences between people. People may have different levels of intelligence, empathy, and creativity, for example, and these differences can be linked to many types of behavioral patterns, including altruistic behavior, learning outcomes in school, and most recently, voting practices.

Compelling new data suggests that those who are cognitively inflexible—who tend to think about the world in terms of strict rules and categories—voted at higher rates for Brexit in the latest U.K. referendum, suggesting that committed nationalists have more rigid thinking and are less likely to change their mind than people in the middle of the political spectrum.

Others have found that a psychological trait called metacognitive skill—the process of thinking about your own performance (imagine, for example, taking a math exam in high school, and being either really good or bad at estimating how well you did)—appears to be predictive of polarized political beliefs.

One set of researchers found that people who hold radical political views, on both the left and the right of the political spectrum, score lower on metacognition, have less insight into their own performance on a simple unrelated perception task, and were slower to learn from their own mistakes. One takeaway from this research is that polarized individuals may simply be less good at considering evidence contrary to their own views, and are more apt to swiftly disregard the opinions of their opponents.

The Contextual Approach

This set of individual differences research echoes a long tradition of thought about political polarization. In 1951, the philosopher Eric Hoffer published his famous essay "The True Believer," in which he dissected what motivates followers of mass movements like communism and Nazism. He wrote: “All movements, however different in doctrine and aspiration, draw their early adherents from the same types of humanity; they all appeal to the same types of mind.” The individual differences approach to political polarization empirically tackles this very notion, pointing out which psychological traits may cause us to hold radical beliefs.

This approach, however, also has its limitations. It is unlikely that political beliefs spontaneously arise within an individual who happens to possess a certain set of cognitive traits. A more likely account is that they develop in interaction with contextual factors such as one’s social environment, life experiences, and media consumption. Hoffer himself alluded to the importance of a partisan context in producing extreme political attitudes: “All active mass movements strive […] to interpose a fact-proof screen between the faithful and the realities of the world.” Therefore, political polarization may well be the result of an intricate interaction between a person’s own cognitive makeup and environmental influences.

The Ways in Which Context Can Shape Our Political Beliefs

A large share of our social environment is consumed through social media sites and phone apps, such as Facebook, Instagram, Twitter, and Snapchat. Since these platforms are designed to show you posts that you like, people are becoming increasingly exposed to views they already agree with. A die-hard progressive may often see posts about the negative impact of climate change, whereas a resolute conservative may be exposed to messages denying that humans have any influence on global warming.

This disparity in information consumption is known as the filter bubble or echo chamber effect, and it can be exacerbated by specific message content. For example, a research team from New York University found that Twitter messages that include moral or emotional words are shared about 20 percent more—but only within polarized political camps, not between opposing parties.

Aside from biased content, social media can also present us with biased information about how other people will act. This is important, since the way people vote in elections is often influenced by their beliefs about how others vote. For example, if 55 percent of voters in a country support party A while 45 percent support party B, it stands to reason that A would win in a general election. However, convincing just 20 percent of A’s supporters that B is, in fact, the most popular candidate, thereby demotivating them from voting at all, can be enough to make B win the election.

In a recent paper, researchers simulated this phenomenon, which they called information gerrymandering, using mathematical models and large-scale experiments with human players. They demonstrated how the structure of a social community can cause information gerrymandering even if opinions are equally distributed in a population, ultimately swaying elections or inducing gridlock even when voters prefer a compromise. Simply put, the structure of our social environment can have a profound impact on our political choices.

Finally, our environment can influence our political beliefs in an even more subtle and unexpected way—by making us view the world through a partisan lens. It has long been known that the human brain processes information by cutting some corners: our brains can effectively fill in missing blanks. For example, imagine walking through your dark house at night. In this case, you will only need a brief shimmer of moonlight on an object to recognize it as your table or chair, and to immediately know where you are. Although your vision might be unclear, your brain completes the picture.

Political perception may behave in similar ways. When we see two candidates in a debate on television, the messages we perceive from the candidates might be ambiguous, such as when politicians use vague language or "dog-whistle" terms that are meaningful only to their own supporters. Just as in the dark house, ambiguous information can be completed by the brain by drawing upon prior knowledge about the candidates.

If this prior knowledge is biased because of your filter bubble, your new perceptions will be biased too. For example, a staunch conservative may interpret the words of Bernie Sanders through a negative lens, even when he happens to make a conservative argument about gun ownership. Our filter bubbles can thus become internalized and long-lasting, making the impact of our social media environment even greater than we may be ready to believe.

Measuring How Context Affects Our Political Mind

One key challenge for psychologists is how to measure these contextual influences on political polarization. It is difficult to map the entire context of an individual’s life—let alone measure how this shapes the subjective lens through which a person views the world.

Recent advances in psychological methods, however, are now providing the necessary tools with which we can take on the challenge of contextualized political polarization research. The power of leveraging big data to analyze one’s online social media environment provides unprecedented access to how social interactions can bias our perceptions, judgments, and actions. Other pioneering methods used in cognitive neuroscience—such as inter-brain synchrony analysis (which has successfully revealed that the synchronization of brain activity patterns between individuals is indicative of how similarly these people interpret ambiguous events in the world)—can be harnessed to examine how political polarization arises.

By capitalizing on these new methods, we can begin to uncover the psychological mechanisms that contribute to a partisan perspective on politics—and potentially discover ways to help everyone keep a more open mind.