Red vs. Blue: The Neuroscience Behind Politics

Bipartisanship: an elusive concept that seems so close to fruition in modern day American politics, yet so far.

The idea of cooperation between Democrats and Republicans is easy to agree with — after all, who wouldn’t want the two political parties to get along? Surely, the government would get much more work done if only people were able to work together.

But as attractive as the idea of “bipartisanship” is, it remains just that — an idea. Despite all the praise that comes with moving towards a more unified political ground, the gap between Democrats and Republicans continues to grow as time goes on. In 2019, only ~15% of Republicans thought that the Democratic party had “good ideas”, and vice versa, a number that has certainly decreased over the years.

This current divide is a growing American political issue, resulting from years of party instability. The past decades have been filled with 49-percent election results, with neither Democratic nor Republican parties succeeding in becoming a concrete majority. Each teeters on the edge of the 50-percent mark, never finding their foothold in the climb for stable political control.

Such desperation only exasperates the need for party loyalty. Any agreement with the “other party” is traitorous — supportive of those who aren’t completely inline with your political beliefs. And when political beliefs slowly become entrenched in personal identity, the divide between two parties only widens.

With the advent of the 21st century, political parties have become more and more polarized — partially due to the widespread use of social media. Platforms encourage those who may have felt their voice unheard to speak up through Facebook and Twitter posts, finding that their opinions may resonate with someone across the country — someone they may have never met. And as they interact more and more with someone they agree with, and only agree with, an echo chamber develops.

It is easy to remain steadfast to your political beliefs when others support it, especially when there are thousands of people over the internet by your side — and soon it becomes a competition of “them” versus “us”.

Everybody likes bipartisanship, and everybody likes working together — but nobody wants to do it. Because actively creating a cooperative political atmosphere requires conceding some of your own opinions, and bringing willingness and cooperation to a center table which no longer exists.

You either agree with a political party, or you don’t.

In a black and white world with no room for negotiation, the definition of “cooperation” has turned from “working together” to “they give up, while we get our way”.

What makes us so unwilling to change our minds? The political instability over the past years has greatly contributed to polarizing differences in ideologies and opinions, but perhaps there is a deeper, more physical reason for this division.

The Emergence of Political Neuroscience

Neuropolitics: the study of the interplay between neuroscience, and political science.

Adherence to a certain political ideology is dependent on a variety of factors, including but not limited to religion, social class, or even social media use. Because of this, a number of political behavior studies are analyzed in the realm of social sciences, choosing to look into how an environment cultivates a certain ideological behavior.

In her 2020 paper on the Psychology of Ideology, Dr. Leor Zmigrod defines ideological thinking as “rigid in its adherence to a doctrine and resistance to evidence-based belief-updating, and favorably-oriented towards an ingroup and antagonistic to outgroups”. An ideological person will consistently resist any arguments or forms of credible evidence that goes against their own, while simultaneously supporting any other opinion that is supportive.

This type of rigid thinking consistently reinforces the mentality of “them”, versus “us”. Though not everybody shares the same group mentality, some may be more vulnerable to this political polarization than most. A standard behavioral science approach would question what could cause someone to be vulnerable to this adherence — perhaps stubbornness or preexisting biases — but doing so locks the issue into a single perspective. Perhaps what we should be asking isn’t what causes, but what already is.

How does brain structure and function impact political ideologies? What exactly happens in the decision making process, and how does this affect which side a ballot is cast in an upcoming election?

The Amygdala

The first major structural difference between liberal and conservative brains starts at the amygdala. Located at the middle of the brain next to the hippocampus, the amygdala is the core center for emotions, motivation, and expression of fear.

The 2013 book, Predisposed, sets a baseline difference between conservative and liberal individuals by outlining the difference in the amygdala’s size: while at an average size for liberals, it is significantly larger in conservatives.

These differences demonstrate contrasting sensitivities in each political party. When compared to liberals, conservatives are much more sensitive to threats and anxiety, but simultaneously more adjusted when it comes to psychological well-being. This sensitivity to fear demonstrates a pattern that helps to explain right-wing ideologies — using an example of the current U.S. federal budget, it becomes clear as to why a conservative brain would be on higher alert against possible threats, potentially causing them to prioritize the need to raise spending for the Department of Defense compared to more egalitarian motions.

Furthermore, a vital aspect of the conservative ideology is individual free-will — one that requires sensitivity to possible risks precisely so that this freedom is not encroached upon by federal laws or restrictions. Especially in light of the COVID-19 pandemic, where many Republican politicians find themselves arguing against mask mandates, we see many Senators fighting against the law in fear that it will violate their personal freedoms.

But despite their sensitivities, conservatives still retain a greater psychological resilience. Whether it may be because of pre-existing self regulatory mechanisms, or a measure of contentment with life that liberals just don’t have, conservative individuals tend to have a higher level of life satisfaction. Most obviously displayed in their own moniker, conservatives are certainly much more content with conserving the status quo.The cultural and social institutions that govern the land work perfectly fine without meddling or interference — and that is enough.

The Anterior Cingulate Cortex

Located on the middle surfaces of the brain’s frontal lobes, the anterior cingulate cortex is the center for complex cognitive functions including empathy, impulse control, and decision-making.

Just as how Predisposed highlighted the importance of the amygdala in conservatives, the same book recognizes liberal individuals to have a greater volume of gray matter (neuronal cell bodies) in their anterior cingulate cortex compared to conservatives. These results were later replicated in a 2020 study on stress resilience and political attitudes, also discovering that liberals were more responsive, but simultaneously tolerant towards ambiguous information.

All of these structural differences showcase a focus on error detection and conflict resolution in liberal brains. When using the same example as before concerning the current U.S. federal budget, liberals are more likely to be more supportive of acts such as universal healthcare — a law that would solve an age-old issue of healthcare access in the country, while making significant changes on the pre-existing system.

It is important here to consider the anterior cingulate cortex’s role in decision-making: when confronted with ambiguous information, liberal individuals are much more hesitant to take a congruent stance so quickly. Perhaps this hesitation is the exact detail that prevents political polarization and party loyalty in both liberals and conservatives alike — the capacity to avoid impulsive black and white thinking.

Above all else, a key neurological difference between these two ideologies remains to be their reaction to uncertain information.

The Yuck Factor

At its core, the largest difference between conservative and liberal brains is their sensitivity to disgust. Over the years, fMRI research has continued to emphasize the relevance of disgust to political partisanship — especially when that disgust is measured in response to nonpolitical imagery.

As seen in conservative brains that have a larger amygdala, conservatives are more sensitive to threats and anxiety, increasing their sense of disgust. In contrast, liberal brains — with a greater volume in the Anterior Cingulate Cortex — are more tolerant of ambiguous data, and less impulsive when making decisions. When all of this is combined, we see conservatives to have a greater disgust response overall compared to liberals.

These responses within political parties were strikingly similar, regardless of the photo’s context. Even if the visual stimuli presented was of a dirty bedroom or physical violence, individuals who reacted with a strong sense of disgust were most likely to align themselves politically as conservative.

Perhaps this sensitivity is not just a litmus test for cleanliness, but an indication of a group mentality. Just like how political partisanship is based on “us” versus “them”, knee-jerk reactions of disgust demonstrate just how rigid an individual is in their loyalty to their political party. With how ideological thinking is dependent on favorable thinking towards an ingroup and antagonism towards any outgroups, strong, impulsive emotions of disgust demonstrate exactly that.

Despite it all, there’s still more to be considered. Being more grossed out at dirty laundry than your peers doesn’t automatically label you as a far-right conservative, and being okay with not cleaning your room for a month doesn’t mean you’re a member of Antifa.

The political spectrum still remains a wide range, and even the brain structures specified previously aren’t sure-fire indicators of an individual’s political alignment. There exists nuance and gradation in each and every thought — not every conservative has a larger than average amygdala, and not every liberal hesitates when making an important decision.

On The Campaign Trail

So what do we do with this information?

As we gain more and more insight into the inner workings of our own brain and political alignments, it’s inevitable that it becomes a part of the campaign process as well.

Political campaigns across the world grow hungrier for information on their voters by the day. And while data analysis of voters’ reactions on Facebook may still feel like recent events, there are dozens of other tactics that well-funded campaigns may employ in order to perfectly appeal to their target audience.

Neuropolitka, a neuromarketing firm in Mexico City that focuses on providing neurological information specifically for large campaign teams, utilizes many of the studies mentioned earlier pertaining to structural differences in the brain. Like so many other companies, they prefer to use electrodes on the scalp to measure and analyze activity in different areas of the brain. Additional algorithms compile this data and pinpoint specific moments where voters might be more attentive to a candidate’s speech, or perhaps the opposite.

The most advantageous part of all this is that the data speaks for itself. Voter information can be hard to compile, much less appeal to — and many citizens don’t even know their own feelings when it comes to politics. Measuring the physical differences and reactions in their brains removes the dreaded subjectivity and complexity that comes with being on the campaign trail, greatly simplifying the entire process. It becomes much easier to rally people to a side when their fears and thought patterns are understood, even more so when it is backed up by neuroscientific evidence.

While the field of neuropolitics may be effective across the world in marketing politicians to seas of voters, its place in a bipartisan America is still beginning. Political differences between individuals are so much more than just clashes of opinions, lifestyles, or financial status — they are ingrained in us so deeply that they are less of how we think, but who we are.

And that will never change.

This article was written Iris Lu, who is a junior undergraduate student at UC Berkeley studying Integrative Biology, and was edited by Oliver Krentzman and Luc LaMontagne, former Publications Leads of Neurotech@Berkeley

This article was originally published in Neurotech@Berkeley’s Fall 2021 Edition of Mind Magazine: Change My Mind. To read more, visit



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We write on psychology, ethics, neuroscience, and the newest in neural engineering. @UC Berkeley