The brain activity of self-described political partisans suggests that a general intolerance of life's uncertainties among both conservatives and liberals could give rise to us-versus-them mentalities, researchers have found. 

A study published May 13 in Proceedings of the National Academy of Sciences explores the theory that aversion to uncertainty leads to black-and-white views that make no room for gray areas, as cognitively rigid people may feel the need to understand the world in predictable and easily categorized terms. 

"There's something called need for closure, a desire to have an understanding and to have it all figured out, or what's known as mental inflexibility or mental rigidity where we need everything to be black and white and not so nuanced," said Oriel FeldmanHall, who is Manning Assistant Professor with the Cognitive, Linguistic & Psychological Sciences Department at Brown University and the study's lead author, in an interview with The Academic Times.

A person displaying uncertainty intolerance is uncomfortable with ambiguities and seeks to resolve them, often by adopting the skewed and immutable narratives of ideologues, according to the study's authors.

"If you look at the rhetoric surrounding a lot of extremist views, they're talking in black and white terms that say, 'This is the way the world is, this is how we have to behave,' and it resolves that uncertainty that people may be averse to," said FeldmanHall. 

"The data show that polarization is increasing both in the U.S. and actually globally, so it's becoming more and more of a problem on the political stage for many countries," she continued. "If we want to get important bills passed in Congress, it's not going to happen with a polarized Senate — or, frankly, with how people chat with each other in the grocery store. It's imperative that we figure out how to bridge the growing divide between conservatives and liberals." 

Previous research has shown that conservatives are less tolerant of ambiguity, but this study is the first to show that the relationship between uncertainty intolerance and political polarization applies to both sides of the aisle — and is also the first to measure the phenomenon on the neurological level, she said. 

For the study, the researchers recruited 22 conservatives and 22 liberals, who reported their political ideology on a sliding scale from "extremely conservative" to "extremely liberal." Their aversion to gray areas was measured using the Intolerance of Uncertainty Scale, which rates respondents' agreement with such statements as, "The ambiguities in life stress me." 

The subjects underwent functional magnetic resonance imaging while viewing political videos, with the researchers comparing their brain responses by using brain-to-brain synchrony, a method of comparing the neurological activity of different people during dynamic social interactions. 

"It's basically looking at how parts of one person's brain responds to incoming stimuli," FeldmanHall explained. "In this case, we showed them three different videos — a BBC Earth documentary, a news segment on abortion and a [vice presidential] debate between Mike Pence and Tim Kaine — and looked at how their neural activity rose and fell over time as they're watching these videos. What we do is compare that trajectory of brain response to another person who watched the same exact content and try to see if those two line up, or correlate."

If two people's brain responses mirror each other while watching the same video, it suggests that they have a shared perception and understanding of the content, she said. If their brain responses diverge, it's taken as evidence that there is not a mutual understanding and that the information is being processed in different ways. 

"What was interesting was that two liberal brains were both very similar when processing information from watching the videos, as were two conservative brains," she said. "The critical finding for us is that one straight level of uncertainty intolerance basically exacerbated the degree to which one's own brain response mirrored another liberal's if they were a liberal, or another conservative's if they were conservative." 

The researchers observed this effect in both conservative and liberal brains, specifically in regions of the brain that play key roles in forming values, emotions and perspectives. 

"Put simply, biased information processing in key regions of interest was not unique to any particular political persuasion but rather affected uncertainty-intolerant partisans across the board," the study's authors noted. 

"This is not a story that is just about conservatives or just about liberals," FeldmanHall emphasized. "This is something that transpires on both sides of the aisle, and so we really have to work hard to bring both sides back into the middle, so to speak." 

For the next step of the project, FeldmanHall and her research team are taking a deeper dive into how psychological states align with one another as people are viewing political information. They want to gain a better understanding of how and when political polarization takes hold of the cognitive process — and, hopefully, how to remedy it. 

"If you're willing to hear more nuanced views that aren't categorized in these very black-and-white terms, if you can get comfortable with that level of uncertainty and nuance, you might be able to hear the other side, and could find ourselves less polarized," she said. 

The study, "Intolerance of uncertainty modulates brain-to-brain synchrony during politically polarized perception," published May 13 in PNAS, was authored by Jeroen M. van Baar and Oriel FeldmanHall, Brown University; and David J. Halpern, New York University and University of Pennsylvania.