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Science & Tech
How do extremists get that way? Probably quite naturally.

In new book, neuroscientist Leor Zmigrod traces connections between brain biology, political beliefs

May 19, 2025 long read

Excerpted from “The Ideological Brain: The Radical Science of Flexible Thinking” by Leor Zmigrod, Visiting Research Fellow ’19

From fascism and communism to eco-activism and spiritual evangelism, ideological groups offer absolute and utopian answers to societal troubles, strict rules for behavior, and an ingroup mentality through dedicated practices and symbols. These features exist across the spectrum of ideological persuasions. Such characteristics can emerge even when the ideology is guided by the sincerest intentions and noblest ideals — even if it claims to protect human dignity or flourishing.

Typically, ideologies are imagined as big visions. Grand and atmospheric. Intangible and out of our personal control. Few of us can outline the precise tenets of pompously uppercased Conservatism, Liberalism, Fascism, Communism, Capitalism, Racism, Sexism, Theism, or Populism, with all their myriad meanings and interpretations. As though from the heavens, these -isms describe the contours of life and prescribe human action, instructing us about the cosmos and how we ought to relate to others within it. For believers, the utopian destiny of an ideology seems carved from the clouds of eternity. A looming force soaring above our heads, meant to be venerated and revered.

The image of ideologies as celestial and static has always troubled me. Ideologies coexist among us, within us, on earth. Not in the skies of history or the towers of political elites. There is no transcendent plane on which they live; no altitudes from which attitudes descend fully formed and holy. Ideologies inhabit individuals. Individual minds convert social doctrines into ideological thinking, a style of thinking that is governed by strict mental rules and carefully regimented mental leaps.

While most definitions perceive ideologies as historical currents and sociological movements, I am interested in examining ideologies as psychological phenomena instead. This psychological lens allows us to ask what an ideology does to its believers and whom it most easily attracts. By spotlighting the processes happening within individual brains, we can probe when an ideology constrains its followers’ mental lives and whether it can ever liberate them.

I invite you to sit down on that gray chair — yes, the one at the desk — and make yourself comfortable. I point to the monitor in front of you and say this is where the experiment will happen. Soon, when I leave the room, you will see instructions pop up on the screen.

Please press ENTER when you are ready.

You press ENTER.

Hello! Welcome to the experiment. Today you will play a series of brain games and problem-solving challenges. For the first game, you will be presented with a deck of cards. Each card will be painted with a number of geometric objects of a specific color and shape. For instance, you may encounter a card with three red circles or a card decorated with a single blue triangle.

The game is a “card-sorting task.” A card will appear at the bottom of your screen. Imagine it is painted with four orange squares. You need to decide how to match it to one of four cards already at the top of the screen.

You will hear a happy jingle when you choose the CORRECT match.

You will hear an angry beep when you choose the INCORRECT match.

Please press ENTER if you understand the instructions.

You press ENTER.

Your first card has three green stars.

You try to match it with the card at the top of the screen decorated with the two blue stars. Maybe stars should go together with other stars.

BEEP!

You sigh. You try again. Maybe your three green stars should be paired with the card containing four green circles? Green-on-green?

Drag, press, release, and … happy jingles! You are right!

You shrug proudly to yourself.

Green-on-green. Easy.

Next card in your deck: one red triangle.

You follow the rule: pair color with color. You place red on red and … jackpot! Jingles again.

You like this rule. You apply it on the next round and the next. Green-on-green, red-on-red, orange-on-orange, blue-on-blue.

The habit is oddly fulfilling. Sliding cards to their rightful grouping, you barely need to think.

After five, or ten, or fifteen rounds — repetition blurs the boundaries of time — the next card in your deck has two blue squares. You go for the blue card at the top of the screen.

BEEP!

An angry, unexpected noise is emitted from the speakers.

You feel betrayed. You forgot the game world was capable of such an offensive sound. It’s insulting.

Maybe it’s just a glitch.

You select the blue card again. It’s second nature to you now, blue on blue.

BEEP!

How can this be? The game world’s inconsistency is like an astonishing infidelity. It makes you want to get up and leave the experiment room.

But you are an addict now. The jingle gave you the feeling (the illusion?) of control, of self-possession. It signaled your cleverness.

In a mad rush you drag the two-blue-squared card toward the three-orange-circled card — there is nothing unifying these cards, not number or color or shape, but you don’t care, you are annoyed. BEEP! The noise barely dissipates before you are lugging the card again, this time toward the four-green-starred card. BEEP! Outraged at this rebellion, you move the mouse in fast, frenzied motions. The rules are not supposed to change halfway through the game. You haul the card to the last unexplored option, swearing to yourself that if this isn’t a match, if the jingle doesn’t return, you will storm out of here in protest, you will wave your arm in the air to call the experimenter back in the room and demand answers, you will — jingle! It worked! You strain your eyes to see what the matching card was. It was two red triangles. Two. Two! Hah! The number of shapes on the card was the same as on the card you held. Hallelujah! Maybe order will return once more. Or maybe this iteration of the task was just a bug. A mere hiccup.

Next time a card pops up on the screen, should you obey the old tradition, follow the color code, or try this new pattern, count the numbers and sort anew? Should you stick to your guns — ignore the anomaly — or should you change, explore, adjust, adapt, revise, and realize that …

This is where I step out of the experiment and tell you that your natural reaction to the change can tell me almost everything about you. Your spontaneous response to the fact that the old rule stopped working and you needed to discover a new one to survive is a kind of inadvertent confession. In this simple game of stars and circles, you have accidentally and inevitably exposed your innermost beliefs.

Why? Because there are two of you. There is the participant who notices the change in the rule governing the game and responds by changing in line with the new demands of the task. This version of you is the adaptable, cognitively flexible individual. When the world changes, you may feel surprise, but you have no fear. You change with the times, with the demands of the environment. You are not strongly rule-bound. You are happy to slip between habits. In fact, you don’t mind having no habit at all. You easily switch between modes of thinking; you are fluid; elastic; you adapt.

However, there is another you. In this version of you, you hate the change. You notice the fact that the old rule no longer works, and you refuse to believe it. You will try again and again to repeat the first rule, but it will be in vain. In fact, you will be punished every time you repeat the original habit. The unnerving BEEP will hit you like a slap in the face. But you won’t move, won’t dodge the blow. You will remain immobile, hanging on tightly to the false belief that somehow the wrathful beep will dissipate and be replaced by a jolly melody. The false and nostalgic belief that the environment around you will magically return and so you don’t need to change. You persevere even when it would be faster to sever ties with the past and move on. This is the cognitively rigid version of you.

Which of these copies of you is you? The flexible or the rigid? The adaptable or the stubbornly unmoving?

Maybe you are neither the first nor the second. You could be somewhere in between: sometimes adaptable, sometimes rigid. Maybe your flexibility depends on circumstance. At ease, you are fluid, adjusting calmly to novelty or surprise. Yet in moments of stress, your movements narrow, your thoughts harden. Anxiety solidifies you, rendering you stiff.

What I, the experimenter, the scientist, have discovered is that how you perform in this game can give me clues about your whole approach to life. Your level of rigidity in this neuropsychological test foreshadows the rigidity with which you believe in ideologies in the social and political world. Your perceptual reflexes are linked to your ideological reflexes.

In fact, your brain comes to mirror your politics and prejudices in strange, profound, and astonishing ways — ways that challenge how we understand the tensions between nature and nurture, risk and resilience, freedom and fate. If our ideological beliefs are related to our cognitive and neural patterns of responding, then we must face new questions about how our bodies become politicized and in what ways we are capable of resisting, changing, and exercising personal agency.

When my colleagues and I invited thousands of people to complete cognitive tests of mental flexibility such as this game, called the Wisconsin Card Sorting Test, we found that the people who are the most behaviorally adaptable on neuropsychological tasks are the same people who — in the realm of ideologies — are most open-minded, most accepting of plurality and difference. The people with the most flexible minds are the people who acknowledge that the intellectual realm can be separated from the personal realm. They do not viscerally hate their interlocuters — they may hate their opinions but they do not project that hatred onto the persons voicing them. In contrast, the most cognitively rigid individuals, those who struggle to change when rules change, tend to hold the most dogmatic attitudes. They hate disagreement and are unwilling to shift their beliefs when credible counterevidence is presented.

Cognitive rigidity translates into ideological rigidity.

This may seem obvious to some: a rigid person is a rigid person. But in fact these patterns are not obvious. When neuroscientists talk about cognition and perception, we are talking about information processing that deals with simple stimuli, with basic sensory information in neutral contexts. Cognitive tasks are composed of uncomplicated elements — colored shapes and moving black dots — displayed on spare, undecorated screens. Through these tasks, we are not assessing how you deal with emotionally evocative or triggering information — information that genuinely scares you or makes you feel a sour pinch of disgust. We are not studying tasks that are too cognitively demanding or complex — ones that would exasperate you needlessly. When neuroscientists measure cognition and perception, we glean individual differences in how a brain forms decisions, learns from the environment, and responds to challenges or contradictions at the most foundational level.

These individual differences are implicit; we have little conscious access to them or control over their expression. A cognitively rigid person may insist that they are spectacularly flexible, and an adaptable thinker may believe that they lack mental malleability. It is astonishing how rarely we know ourselves.

As a result, the link between mental inflexibility and ideological rigidity reveals a critical insight about how our brains work and how ideologies penetrate human brains. It suggests that our characteristic rigidity, rigidity that is evident when we deal with any information — even orange stars and blue circles — can propagate up to higher-level rigidities that emerge in our ideological choices and actions.

Even when we are not thinking explicitly about politics, the reverberations of our ideological convictions can be felt and measured. Ideological imprints on the brain can be observed when our minds are left to roam and drift, when we imagine and invent, when we observe and interpret even the most neutral of situations. The ideological brain’s rigidities and idiosyncrasies manifest where we least expect them, in our most private sensations and physiological responses, beneath the surface of our public convictions and conscious feelings. The dangers of dogmatic ideologies are therefore not just political — the consequences are neural, individual, and existential.

Published by Henry Holt and Company. Copyright © 2025 by Leor Zmigrod. All rights reserved.