The 4 psychological markers of ideological extremism

Psychology is largely the study of correlations and the extent to which we can establish connections between correlations and causation. We are often told that “correlation does not mean causation” in the world of data. A classic example: Ice cream sales have a positive correlation with crime rates. Ice cream does not cause criminality, but apparently, the summer months cause both.

But this is no hard rule. Although correlation doesn’t always mean causation, it can often seriously imply or suggest it. Psychologists grapple with this all the time. For example, it’s been anecdotally obvious for millennia that people who sleep fewer hours tend to perform worse on memory, attention, and decision-making tasks, and young people with irregular bedtimes often achieve poorer grades. That’s “just” a correlation. It’s only relatively recently that we have the neuroimaging and neuroscientific apparatus to prove causality.

The specter of correlation/causation hovered over this week’s Mini Philosophy interview with the prizewinning author Leor Zmigrod about her recent book, The Ideological Brain. Zmigrod’s book explores extreme ideologies, and her career has been spent finding these correlations. During our interview, Zmigrod shared the findings of both her book and career to argue that there are four principal factors that correlate with someone holding extreme ideological beliefs.

In other words, these are the factors that most often lead a person to become an extremist.

Cognitive rigidity

“Cognitive rigidity is the tendency to see the world in a really binary way,” Zmigrod says. “It’s where you really struggle to adapt to change, and you tend to think along one mental track rather than switching between different modes of thinking.”

There are many ways you can test for this kind of rigidity, but Zmigrod’s favored method is to ask someone to imagine the possible uses for an item. Let’s say I showed you a Coca-Cola bottle: What could you use it for?

The more rigid reader will find it hard to think outside the paradigm of “it can hold liquid.” Others will see it as a candle holder, a tiny terrarium, a vase, a salt shaker, and so on. This rigidity in thought is often correlated with extreme ideologies. The more rigid a person’s thoughts, the more they incline toward extremism.

Emotional volatility

The second factor is “emotional impulsivity” or volatility. These people will “tend to be the most seeking of thrills and sensations in their daily lives,” Zmigrod says. “They want that novelty and that sensation. This is the person who’s going to run to the front of the line.”

This isn’t overly surprising. It makes sense that people who are extreme in their day-to-day lives might tend toward extreme ideologies. But it also involves another set of co-appearing characteristics — what Zmigrod calls the tendency some people have “to gravitate towards violent solutions and self-sacrifice.”

If you think about your friends, who is the most likely to pick a fight? Who’s the most likely to do something impulsive and jump without looking? Well, you might want to check how ideologically extreme they are.

Amygdala

The next two markers of extremism are invisible to us. Unless, that is, you happen to be reading this article on a wheely stool next to an MRI machine. In our interview, Zmigrod revealed how there are two neurobiological aspects of a person’s brain that correlate with an increased likelihood of extremism. The first centers on the amygdala.

“The amygdala is responsible for the processing of negative emotions like fear, threat, and disgust,” Zmigrod says. “And that brain area is actually larger in right-wing believers than left-wing believers. And this is a finding that’s been consistent across multiple countries, hundreds of participants, that there’s this brain area that might predispose you either to a left-wing or a right-wing ideology.”

We have correlates and data sets, evidence and observations. It’s left to us, the readers, to draw the conclusions we think are there to draw.

Prefrontal cortex

The other neurobiological aspect of extreme ideology is related to our “more sophisticated decision-making and rationality,” which is found in the prefrontal cortex. According to a 2025 study by Adrián-Ventura et al., published in Neuroscience, individuals with a thinner “dorsomedial PFC cortex” tended to exhibit stronger left- and right-wing authoritarian traits, after controlling for age, sex, and total brain volume.

As Zmigrod puts it, “the brain differs in function and structure depending on whether you believe a fundamentalist ideology or a more moderate one.”

As we’ve already touched on, these are only correlative observations. More work, and possibly more technology, is required to fully prove causation in the way we have with sleep deprivation. But even then, an answer will likely never be black and white.

Working backward

Belief formation is a complex area that brings neuroscientists, psychologists, and philosophers around the table to shout it out. There will never be one factor we can point to and say, “Yep, this means Timmy will be an extremist.” Nature and nurture, brain and environment, genetics and upbringing all bubble together in a complex, epistemological goulash.

What’s interesting, though, is the corollary of these observations, especially the first two. If we know that cognitive rigidity and emotional volatility incline a person to extremism, we can reverse-engineer the problem. If we raise our children to be less emotionally volatile and help our friends to flex their cognitive worlds, we can hope to reverse a trajectory of increasing extremism. When people retreat to their silos and scream at each other in increasingly loud ideological tribes, the only outcome is bad. Perhaps we can buck the trend. We just need to think of more uses for a Coke bottle.