Red Brain, Blue Brain?

Neuroscience can tell us a lot about political polarization

Are there really conservative and liberal brains? Image Credit: PM Images/Getty Images

“I am slightly to the right of Attila the Hun.” These were the first words that my future father-in-law spoke to me after I was introduced to him at Thanksgiving many years ago. Obviously his words were meant for shock effect—to the best of my knowledge, no one in my wife’s family have been accused of sacking and pillaging cities across Europe. But they’re also a reminder of how political polarization is so prevalent in our society that our dinner tables can sometimes feel like debate stages.

Lately, there seems to be very little consensus between the political divisions in our country on almost any topic. Some historians are even comparing the current political divide to the late 1850s, when the Supreme Court ruled on the Dred Scott case setting the stage for the onset of the Civil War. A recent survey supports that analogy, suggesting that a significant number of Americans on both sides of the political divide think that the country could—and even should—head to some type of divorce. Setting aside the wisdom (or lunacy) of that position, as any marriage counselor will attest, when two sides are considering a divorce, the first thing that should be addressed is the finding of root causes that might be driving the division.

Factors such as parents’ ideology, race, ethnicity, gender, age and economic status correlate very strongly with ideology. But looking at these factors over the decades, it is hard to find a pattern that could easily explain the recent polarization that has occurred. However, one relatively recent change is the evolution of how Americans get their news—and the editorializing that goes with the news. We live in an environment in which the information one person receives is radically different from what the next receives. A recent study in the Proceedings of the National Academy of Science demonstrated that even those who get their news from cable are consistently seeing more bias between how stories are portrayed.

If current political polarization is being driven by how we receive information (Fox vs. CNN, for example), generating distinct perceptions and emotions (“The election was stolen!” “They are inciting a riot!”) and how we decide what to do (like who we vote for and how we engage in debate), then neuroscience has a lot to offer on this subject. At its most basic level, the brain has three main jobs to do: bring in sensory information about what is happening in the world, generate a perceptional awareness and feeling of what one is experiencing and decide what to do about it. Our brains are taking a wide range of politically tinged inputs—TV shows, radio programs, news articles, debates with friends—and based on differences in our brain pathways, they’re determining our political opinions and actions—often in ways that clearly predict where we might fall on the political spectrum.

Are We Seeing the Same Thing?

Recently, Americans watched in horror and disgust as Tyre Nichols was brutally beaten to death by police officers after being pulled over for a possible traffic violation. What if our brain responses to that video were different based upon our ideological views? Research suggests that might be the case.

In one study, scientists using functional magnetic resonance imaging (fMRI) technology measured the blood oxygen level dependent (BOLD) response in the brains of subjects who were presented a series of nonpolitical images. These images were categorized as neutral (e.g., a building), pleasant (e.g., puppies), disgusting (e.g., mutilated animal remains) and threatening (e.g., a car accident). Subjects were asked to rate how they felt about each of the images and then they filled out a survey to assess their political views. The data was then separated into three equal groups of conservative, moderate and liberal subjects based upon the political survey.

Interestingly, there was no difference in how the subjects reported their feeling about the images. Yet when viewing disgusting images, there was a distinct brain activity profile for conservatives versus liberals. In seven different brain regions, conservative subjects had faster onset and greater peak level of activity when viewing disgusting images compared to liberals. Some of these areas (like the amygdala and regions of the prefrontal cortex) deal specifically with processing emotional information, leading the authors of the study to propose that this evidence supports the hypothesis that conservatives have a greater negativity bias than liberals, maybe giving greater relevance to sensory information that carries with it negative emotion. For example, in the aftermath of George Floyd’s death, protests erupted across the country and especially in Minneapolis. Images of demonstrators demanding justice were interlaced with images of those who were damaging and looting business establishments. A negativity bias may have driven some conservatives to react more strongly to the looters, creating different opinions on the value of the protests.

If true, this most likely would be an unconscious bias, as the subjects consciously rated the images with the same degree of emotion regardless of whether they were conservative or liberal. Consistent with this being an unconscious bias, the brain region that had the greatest predictability in this experiment was the thalamus, a region of the brain that helps us selectively attend to one part of our sensory experience over others. For example, if you were on a crowded subway, being inundated with background noise, obnoxious smells and variable light and shadows, you could still hold a conversation with the person sitting next to you partly because your thalamus is giving greater weight to the words of your fellow passenger before you are even conscious of the words being spoken. Perhaps, then, the conservatives’ brains in this study were driving them to pay more attention and give greater weight to negative sensory information being presented.

If the hypothesis that conservatives’ brains tend to generate stronger responses to images that portray negative emotional stimuli is correct, then one might expect that news media that capitalized on presenting stories in that way might have greater resonance with conservative voters rather than liberal ones. That would make a great story; however, data doesn’t support that conclusion. In a recent study looking at how news organizations use Twitter, both conservative- and liberal-leaning news sources equally used negativity in their tweets more than positivity, and the negative posts had more engagement from followers regardless of ideological leaning. This study, though, only looked at whether followers responded with “favorites” or “retweets.” Maybe there is a difference in how conservatives and liberals processed the negative information that is more complex than the behavior of simply finding the story engaging. After all, the brain study demonstrated a negativity bias in all subject groups and only suggested a more pronounced response in the more conservative subjects. It’s definitely something that future researchers ought to look into.

Maybe We’re Just Wired Differently

We all saw the videos of the crowd breaking through the barriers of the Capitol on January 6, 2021. Each of us can explain what we think happened and describe what we felt and thought about the actions of the participants. While there may be some variance in our understanding of the events that occurred, there appears to be wider disparity in our emotional response and how we use that emotional response to generate an opinion of the event.

A neuroscience perspective would explain the difference as being due to the first task—the determination of our emotional response—being generated primarily from our sensory systems bringing information into our brains following relatively consistent pathways, while the second task—how we use our emotional response to generate an opinion—is being generated from our perceptional awareness pathways, which are dispersed throughout the brain and have much greater variability in how they engage with one another. In other words, could conservatives’ and liberals’ perceptions of events be different because the pathways that our brains use to make those perceptions are different?

In the last few years, neuroscientists have begun to utilize a new technique to examine brain pathway differences. Instead of using the standard BOLD response which focuses on activity differences in discrete brain regions, some scientists are now using fMRI data to look at a different brain characteristic called functional connectivity. This means that scientists try to determine how the activity in one region of the brain correlates with the activity in other regions of the brain while engaged in different mental functions. Research using a functional connectivity lens has started to shift the neuroscience field away from explaining brain differences as due to differences in particular brain regions to one in which differences might be explained by how different brain regions are wired together.

Last year, a neuroscience group based at The Ohio State University examined a group of young adults who volunteered to have their brains imaged while engaged in a variety of functional tasks. As in the previous study, they were surveyed for their ideological views as well as gathering demographic data that is typically used to predict ideology such as parents’ ideology, education, religiosity, income and where they grew up and currently live. In four of the nine tasks, there were significant differences between conservative and liberals in how brain regions were activated together.

Even more impressively, the functional connectivity difference was so distinct that just by using the brain scans alone from three of the tasks, the neuroscientists were able to predict a person’s ideology more accurately than a social scientist would be using the demographic data.

If the neuroscientists had the subjects view a speech by Donald Trump, arguably the most polarizing political figure of the 21st century, or watch politicians debate abortion, it probably wouldn’t surprise people that different pathways were activated in conservatives’ and liberals’ brains. The surprising part, is that none of the functional tasks in which the subjects engaged had a political or ideological component. Rather, the tasks were designed to engage empathy, memory retrieval and reward (for example, the reward task had the subjects press a button whenever a white square appeared on a screen and would win or lose fictional money based upon how fast they pressed the button). While many parts of the brain were involved in forming the distinct functional pathways between conservatives and liberals in these tasks, three areas of the brain had the strongest differences in how they were functionally connected to other areas: the amygdala, the hippocampus and the inferior frontal gyrus.

The amygdala helps to generate the subjective component of our emotions, so it’s possible that different emotional responses can be generated by differences in how the amygdala is connected to other parts of the brain. For example, some viewing the events of January 6 may have had a stronger empathetic response to the members of the crowd whose frustration with the most recent election was very evident, while others may have had stronger empathetic response to the members of Congress who were fleeing to safety.

The hippocampus helps us form and retrieve our memories, but not in the way that a computer does. When your computer saves a document, for example, it doesn’t care how you feel about the document or whether the document is similar to other documents that you have saved. When the computer retrieves a document, it doesn’t care what you have experienced in the time since you last saved the document. The hippocampus, by contrast, cares about all of that—and much more. So when watching the events of January 6, different people may have formed different memories based upon how they felt and how it related to other memories. And as they retrieve the memory, the subsequent events and experiences of their lives will alter and change the memory. For example, before, during and after January 6, Donald Trump claimed that the election was stolen from him. A conservative and liberal might use that information differently in their hippocampus as they both form the initial memory of how they felt about the event and then later as they retrieve that memory and use it to form opinions of other events, such as Twitter banning Donald Trump.

That brings me to the inferior frontal gyrus. There are a number of different functions in which the inferior frontal gyrus might be involved, but one that might be relevant to the political brain is impulse control. Intuitively, most of us have the sense that we have some agency in making decisions on what we do and don’t do—our free will. Our judgments of ourselves and others is woven into decisions about whether or not to act. We reach for that second helping of pie, and we beat ourselves up for not having the will to resist. We see the protestors storming the Capitol, and we judge them for the choices they made.

Neuroscientists have never found evidence of a brain feature that produces free will, which means one of three things: There is no free will (at least as defined by our intuition); there is free will but it is not produced by the brain; or neuroscientists simply haven’t found where free will is produced yet due to limitations of technology or experimental paradigm. Instead of free will, neuroscientists have found areas like the inferior frontal gyrus which is active during times in which we inhibit our thoughts from becoming actions.

It is intriguing, then, that this region has different functional connections based upon ideology. This suggests that different inputs might drive conservatives and liberals to respond differently based upon what is being inhibited, and what is not. A psychological study supported such a difference when they tested subjects’ ability to inhibit an incongruent stimulus—in this case, color words that are a different color, like the word “red” printed in the color green. When one sees the word “red,” but is in a green font, the brain has to inhibit the response to the color of the font to be able to accurately identify the word. Conservative subjects did this task faster with no loss of accuracy compared to liberal subjects. In the immediate aftermath of the Tyre Nichols killing, there was a striking difference of opinion on whether his death was related to racism. Maybe the incongruence of Black officers beating to death a Black motorist was used differently by conservatives and liberals to inhibit thoughts from turning into opinions on starkly different perceptional awareness of why Nichols died.

Are There Really Red and Blue Brains?

There is as much evidence that conservatives and liberals have distinct signatures of activity in their brains as there is that conservatives live in red states and liberals live in blue states: It’s pretty plain to see. Just like the demographic data, though, the brain data is not absolute. In each data set, there are plenty of examples of individuals whose brain activity didn’t fit the prediction of ideology. Also, because there is a strong overlap between ideology and other factors such as social economic profile and education, the brain scans may instead be picking up differences due to environmental factors such as early life experiences and neuroplasticity effects due to education. Just like red and blue states can flip, or turn purple, one shouldn’t assume that current brain activity is a predictor of future political views.

Yet all caveats aside, the brain seems to have much to tell us about how conservatives and liberals think. That those across the ideological spectrum have different conscious thoughts about topics like taxes, healthcare, gun control, the role of government and strengths and weakness of current and past political leaders is not surprising. What this latest brain research is telling us, though, is that the differences run deeper, impacting mental activity at an unconscious level and affecting how brain regions connect with one another. More neuroscientists are now tackling research questions that have traditionally been rooted in the social sciences. We’re learning that neuroscience can not only give us new insights into how we think about politics, but it is also giving us insights into how our politics can make us think differently.

Submit a Letter to the Editor
Submit your letter
Subscribe to our newsletter