Neuroimaging research provides new insights into the neural underpinnings of how information is interpreted differently by conservatives and liberals.
The study, published in the Proceedings of the National Academy of Sciences, found differences in activity in a key brain region among conservatives and liberals who watched an identical set of videos about immigration policy.
“I think most of us have seen some demonstration of this phenomenon, or even witnessed in real life — show the same news footage to people with different political affiliations, and they ‘see’ something different,” said researcher Yuan Chang Leong, a postdoctoral researcher at the Helen Wills Neuroscience Institute at the University of California, Berkeley.
As an example, he pointed to a recent segment on CBS “This Morning,” in which conservatives and liberals were shown the same videos — but had very different perceptions of who was the aggressor.
Americans have become more politically divided in recent decades. @TonyDokoupil tested just how far we’ve grown apart. He found people of different political leanings are seeing very different things. pic.twitter.com/JIUq0I7Yfa
— CBS Mornings (@CBSMornings) September 18, 2020
“Why do people perceive and respond to the same political information differently? As a neuroscientist, I was curious as to how partisan biases relate to information processing in the brain,” Leong said.
The researchers used functional magnetic resonance imaging (fMRI) to record the brain activity of 38 American participants as they watched news clips, campaign ads, and public speeches related to immigration policy. The videos were about 1 to 2 minutes long and were selected to represent both liberal and conservative viewpoints on immigration policy.
Prior to being scanned, the participants completed a questionnaire that assessed their support for six immigration policies.
After each video, the participants rated on a scale of one to five how much they agreed with the general message of the video, the credibility of the information presented and the extent to which the video made them likely to change their position and to support the policy in question.
To calculate group brain responses to the videos, the researchers used a measure known as inter-subject correlation, which can be used to measure how similarly two brains respond to the same message.
As expected, political ideology was unrelated to sensory processing. Leong and his colleagues found that the videos resulted in neural responses in the auditory and visual cortices that were shared across participants regardless of the their political attitudes.
But the researchers observed a divergence between conservative-leaning and liberal-leaning participants in the dorsomedial prefrontal cortex . The dorsomedial prefrontal cortex has been “implicated in a broad range of complex cognitive functions, including episodic memory retrieval, impression formation, and reasoning about other people’s mental states,” the researchers said.
This divergence, which the researchers dubbed neural polarization, was increased by the use of risk-related and moral-emotional words in the videos. It was also related to whether the participants changed their views.
“Brain responses diverged between conservatives and liberals watching the same videos about immigration policy. For a given individual, the closer their brain activity resembled that of the ‘average conservative’ or ‘average liberal’ person, the more likely they were to adopt that group’s position after watching the videos,” Leong told PsyPost.
“This suggests that the more participants adopt the conservative interpretation of a video, the more likely they are to be persuaded to take the conservative position, and vice versa. The divergence in brain responses was strongest when the videos used language that highlighted threat, morality and emotions, suggesting that certain words are more likely to drive polarization.”
“Together, these results suggest a neural basis for partisan biases in interpreting political messages and the effects these biases have on attitude change. The results also highlight the type of language most likely to drive biased interpretations,” Leong said.
But this neural polarization does “not imply that conservatives and liberals are ‘hardwired’ to disagree,” Leong continued. “Our experiences, and the media we consume, likely contribute to the polarized neural responses.”
Future research should also examine whether the results generalize to other political issues.
“We scanned participants watching videos about a single issue — immigration. It would be important to study if the results would generalize to other polarizing issues, e.g., abortion, gun control. Given that those issues are also often framed in threat, moral, and emotional terms, we believe this would be the case, but we would need to run the study to know with greater certainty,” Leong said.
Future research could also examine how neural polarization influences sharing behavior and the distribution of information. Leong hopes to use his findings to inform interventions aimed at narrowing the divide between conservatives and liberals.
“Political beliefs have a powerful influence over how people perceive, interpret and respond to new information. People can watch the same news footage and draw completely opposite conclusions. I think this highlights why it is so difficult to bridge the partisan divide, and that trying to persuade partisans with ‘more information’ might not be the most effective strategy,” he explained.
“If our goal is to reduce polarization and change minds, we need to think carefully about how we frame and structure political information, for example, by framing messages to appeal to the core values of the respective voter (for e.g., see Feinberg and Willer, 2012, The Moral Roots of Environmental Attitudes published in Psychological Science).”
The study, “Conservative and liberal attitudes drive polarized neural responses to political content“, was authored by Yuan Chang Leonga, Janice Chen, Robb Willer, and Jamil Zaki.