Is Our Ideology Hidden in Our Brain’s “Gag Reflex”?

We all like to think of ourselves as rational beings. We claim that we read party manifestos before voting, analyze economic data, and engage in deep philosophical reflection about “the survival of the nation” or “freedoms.”

But what if I told you that beneath all this intellectual veneer, some of your political instincts may be shaped in your gut—or rather, in the brain’s most primitive, reflex-driven circuits?

I’m not the one making this up. A research team affiliated with the Virginia Tech Carilion Research Institute reported findings along these lines in a 2014 study published in Current Biology—a paper led by neuroscientist P. Read Montague.

The Experiment: Listening to a Politician, or Looking at Something Repulsive?

The setup was simple. Participants were placed in an fMRI scanner to measure their brain activity. But instead of playing political speeches, the researchers showed them something completely different:

Disgusting images.

A filthy toilet, feces, a plate of food covered in bugs, a rotting piece of flesh…

 fMRI Scanner

A quick note on what fMRI actually does: fMRI isn’t “mind reading.” It tracks changes in blood flow and oxygenation in the brain. When neurons in a region work harder, that area demands more energy, and the body sends more oxygen-rich blood there; the scanner captures this indirectly via what’s known as the BOLD signal. In other words, the colorful “glows” aren’t thoughts—they’re a proxy for where the brain is working more in that moment.

fMRI brain activation heatmap showing BOLD signal changes across multiple regions

While participants viewed the images, the researchers recorded activity patterns in regions often associated

 with threat processing (like the amygdala) and visceral/affective processing (including the insula). After the images, participants completed a standard political survey covering issues like gun control, abortion, same-sex marriage, and immigration.

A Striking Prediction

The results were unsettling. The neural response to those “disgust” images carried real predictive power about where a person landed on the liberal–conservative spectrum.

The pattern looked like this:

• People whose brains showed a stronger “disgust/threat” response tended to score more conservative on the survey.

• Those who were more indifferent—or had a higher disgust threshold—tended to score more liberal.

And the association wasn’t trivial: the researchers reported that brain responses to disgust stimuli could statistically distinguish liberal–conservative tendencies with strong performance, with some analyses reaching AUC ~0.85 under a specific sub-condition. (Note: In statistics, an AUC of 0.85 indicates an 'excellent' ability for the model to distinguish between the two groups.)

Is Conservatism an “Immune System”?

So how could there be any connection between feces or insects and “state governance”? One answer may lie in evolutionary logic.

Across human history, disgust has been a survival reflex. Feeling revulsion toward rotten meat, feces, or unknown creatures helped our ancestors avoid poisoning and disease. The body had to defend its boundaries.

A conservative mindset may be more likely to translate that same “protection and purity” impulse onto the social plane:

Biologically: “This spoiled food must not enter my body.”
Politically: “This foreign culture/immigrant/idea must not enter my society.”

For conservatives, a “border” may feel like more than a line on a map—it can function as a psychological shield that protects perceived integrity. Liberals, by contrast, may be more open to novelty (or less sensitive to certain threat cues), and therefore approach social change with greater flexibility.

Conclusion: Ideology Has a Body

This experiment left me with an uncomfortable thought: we’re not always the free-willed, purely rational thinkers we imagine ourselves to be. Our political fights, parliamentary debates, or online mob frenzies may sometimes reflect older biological circuits playing out in a modern arena.

Maybe the reason we can’t convince each other isn’t only that our arguments are weak—but that our brains’ thresholds for “threat” and “disgust” can differ in ways that arguments don’t easily reach.

Politics isn’t just a mental chess match; it can be a physical reflex. It may be our hand that stamps the ballot, but behind that decision, threat/disgust thresholds that kick in before arguments (even if not solely decisive) may also play a role. 

**Source:** Ahn et al. (2014), *Current Biology*. DOI: 10.1016/j.cub.2014.09.050