The Two-Thousand-Year-Old Assumption

The time-honored story of emotion goes something like this: We all have emotions built-in from birth. They are distinct, recognizable phenomena inside us. When something happens in the world, whether it’s a gunshot or a flirtatious glance, our emotions come on quickly and automatically, as if someone has flipped a switch. We broadcast emotions on our faces by way of smiles, frowns, scowls, and other characteristic expressions that anyone can easily recognize. Our voices reveal our emotions through laughter, shouts, and cries. Our body posture betrays our feelings with every gesture and slouch.

And yet... despite the distinguished intellectual pedigree of the classical view of emotion, and despite its immense influence in our culture and society, there is abundant scientific evidence that this view cannot possibly be true. Even after a century of effort, scientific research has not revealed a consistent, physical fingerprint for even a single emotion.

When scientists set aside the classical view and just look at the data, a radically different explanation for emotion comes to light. In short, we find that your emotions are not built-in but made from more basic parts. They are not universal but vary from culture to culture. They are not triggered; you create them. They emerge as a combination of the physical properties of your body, a flexible brain that wires itself to whatever environment it develops in, and your culture and upbringing, which provide that environment. Emotions are real, but not in the objective sense that molecules or neurons are real. They are real in the same sense that money is real — that is, hardly an illusion, but a product of human agreement.

The Search for Emotion’s “Fingerprints”

If we put all the scientific evidence together, we cannot claim, with any reasonable certainty, that each emotion has a diagnostic facial expression.

Despite tremendous time and investment, research has not revealed a consistent bodily fingerprint for even a single emotion.

I didn’t know it at the time, but as I considered emotion categories in all their diversity, I was unwittingly applying a standard way of thinking in biology called population thinking, which was proposed by Darwin. A category, such as a species of animal, is a population of unique members who vary from one another, with no fingerprint at their core. The category can be described at the group level only in abstract, statistical terms. Just as no American family consists of 3.13 people, no instance of anger must include an average anger pattern (should we be able to identify one). Nor will any instance necessarily resemble the elusive fingerprint of anger. What we have been calling a fingerprint might just be a stereotype.

This is one of the most surprising things I learned as I began to study neuroscience: a mental event, such as fear, is not created by only one set of neurons. Instead, combinations of different neurons can create instances of fear. Neuroscientists call this principle degeneracy. Degeneracy means “many to one”: many combinations of neurons can produce the same outcome. In the quest to map emotion fingerprints in the brain, degeneracy is a humbling reality check.

Another surprising thing I learned while training to be a neuroscientist, along with degeneracy, is that many parts of the brain serve more than one purpose. The brain contains core systems that participate in creating a wide variety of mental states. A single core system can play a role in thinking, remembering, decision-making, seeing, hearing, and experiencing and perceiving diverse emotions. A core system is “one to many”: a single brain area or network contributes to many different mental states. The classical view of emotion, in contrast, considers particular brain areas to have dedicated psychological functions, that is, they are “one to one.” Core systems are therefore the antithesis of neural fingerprints.

To be clear, I’m not saying that every neuron in the brain does exactly the same thing, nor that every neuron can stand in for every other. (That view is called equipotentiality, and it’s been long disproved.) I am saying that most neurons are multipurpose, playing more than one part, much as flour and eggs in your kitchen can participate in many recipes.

Emotions Are Constructed

Simulations are your brain’s guesses of what’s happening in the world. In every waking moment, you’re faced with ambiguous, noisy information from your eyes, ears, nose, and other sensory organs. Your brain uses your past experiences to construct a hypothesis — the simulation — and compares it to the cacophony arriving from your senses. In this manner, simulation lets your brain impose meaning on the noise, selecting what’s relevant and ignoring the rest.

Simulation is the default mode for all mental activity. It also holds a key to unlocking the mystery of how the brain creates emotions.

Using your concepts, your brain groups some things together and separates others. You can look at three mounds of dirt and perceive two of them as “Hills” and one as a “Mountain,” based on your concepts. Construction treats the world like a sheet of pastry, and your concepts are cookie cutters that carve boundaries, not because the boundaries are natural, but because they’re useful or desirable.

Now consider this: what if your brain uses this same process to make meaning of the sensations from inside your body — the commotion arising from your heartbeat, breathing, and other internal movements? From your brain’s perspective, your body is just another source of sensory input. Sensations from your heart and lungs, your metabolism, your changing temperature, and so on, are like the ambiguous blobs of figure 2-1. These purely physical sensations inside your body have no objective psychological meaning. Once your concepts enter the picture, however, those sensations may take on additional meaning. If you feel an ache in your stomach while sitting at the dinner table, you might experience it as hunger. If flu season is just around the corner, you might experience that same ache as nausea. If you are a judge in a courtroom, you might experience the ache as a gut feeling that the defendant cannot be trusted. In a given moment, in a given context, your brain uses concepts to give meaning to internal sensations as well as to external sensations from the world, all simultaneously. From an aching stomach, your brain constructs an instance of hunger, nausea, or mistrust.

An emotion is your brain’s creation of what your bodily sensations mean, in relation to what is going on around you in the world.

I call this explanation the theory of constructed emotion: In every waking moment, your brain uses past experience, organized as concepts, to guide your actions and give your sensations meaning. When the concepts involved are emotion concepts, your brain constructs instances of emotion.

The theory of constructed emotion tosses away the most basic assumptions of the classical view. For instance, the classical view assumes that happiness, anger, and other emotion categories each have a distinctive bodily fingerprint. In the theory of constructed emotion, variation is the norm. When you are angry, you might scowl, frown mildly or severely, shout, laugh, or even stand in eerie calmness, depending on what works best in the situation. Your heart rate likewise might increase, decrease, or stay the same, whatever is necessary to support the action you are performing.

In the theory of constructed emotion, a category of emotion such as sadness, fear, or anger has no distinct brain location, and each instance of emotion is a whole-brain state to be studied and understood. Therefore we ask how, not where, emotions are made.

Emotions are social reality. A physical event like a change in heart rate, blood pressure, or respiration becomes an emotional experience only when we, with emotion concepts that we have learned from our culture, imbue the sensations with additional functions by social agreement. From the widened eyes of a friend we may perceive fear or surprise, again depending on which concepts we use. We must not confuse physical reality, such as changes in heart rate or widened eyes, with the social reality of emotion concepts.

The Origin of Feeling

Simple pleasant and unpleasant feelings come from an ongoing process inside you called interoception. Interoception is your brain’s representation of all sensations from your internal organs and tissues, the hormones in your blood, and your immune system.

The stimulus-response view, while intuitive, is misguided. Your brain’s 86 billion neurons, which are connected into massive networks, never lie dormant awaiting a jump-start. Your neurons are always stimulating each other, sometimes millions at a time. Given enough oxygen and nutrients, these huge cascades of stimulation, known as intrinsic brain activity, continue from birth until death. This activity is nothing like a reaction triggered by the outside world. It’s more like breathing, a process that requires no external catalyst

You might wonder what this hotbed of continuous, intrinsic activity is accomplishing, besides keeping your heart beating, your lungs breathing, and your other internal functions working smoothly. In fact, intrinsic brain activity is the origin of dreams, daydreams, imagination, mind wandering, and reveries, which we collectively called simulation in chapter 2. It also ultimately produces every sensation you experience, including your interoceptive sensations, which are the origins of your most basic pleasant, unpleasant, calm, and jittery feelings.

Intrinsic brain activity is millions and millions of nonstop predictions. Through prediction, your brain constructs the world you experience. It combines bits and pieces of your past and estimates how likely each bit applies in your current situation.

Prediction is such a fundamental activity of the human brain that some scientists consider it the brain’s primary mode of operation.

If your brain were merely reactive, it would be too inefficient to keep you alive.

Evolution literally wired your brain for efficient prediction.

You might think that your perceptions of the world are driven by events in the world, but really, they are anchored in your predictions, which are then tested against those little skipping stones of incoming sensory input.

Through prediction and correction, your brain continually creates and revises your mental model of the world. It’s a huge, ongoing simulation that constructs everything you perceive while determining how you act.

If this talk of prediction and correction seems unintuitive, think about it this way: your brain works like a scientist. It’s always making a slew of predictions, just as a scientist makes competing hypotheses. Like a scientist, your brain uses knowledge (past experience) to estimate how confident you can be that each prediction is true. Your brain then tests its predictions by comparing them to incoming sensory input from the world, much as a scientist compares hypotheses against data in an experiment. If your brain is predicting well, then input from the world confirms your predictions. Usually, however, there is some prediction error, and your brain, like a scientist, has some options. It can be a responsible scientist and change its predictions to respond to the data. Your brain can also be a biased scientist and selectively choose data that fits the hypotheses, ignoring everything else. Your brain can also be an unscrupulous scientist and ignore the data altogether, maintaining that its predictions are reality. Or, in moments of learning or discovery, your brain can be a curious scientist and focus on input. And like the quintessential scientist, your brain can run armchair experiments to imagine the world: pure simulation without sensory input or prediction error.

Interoception is actually a whole-brain process, but several regions work together in a special way that is critical for interoception. My lab has discovered that these regions form an interoceptive network that is intrinsic in your brain, analogous to your networks for vision, hearing, and other senses. The interoceptive network issues predictions about your body, tests the resulting simulations against sensory input from your body, and updates your brain’s model of your body in the world.

To simplify our discussion drastically, I’ll describe this network as having two general parts with distinct roles. One part is a set of brain regions that send predictions to the body to control its internal environment: speed up the heart, slow down breathing, release more cortisol, metabolize more glucose, and so on. We’ll call them your body-budgeting regions.* The second part is a region that represents sensations inside your body, called your primary interoceptive cortex.

Just as a company has a finance department that tracks deposits and withdrawals and moves money between accounts, so its overall budget stays in balance, your brain has circuitry that is largely responsible for your body budget. That circuitry is within your interoceptive network. Your body-budgeting regions make predictions to estimate the resources to keep you alive and flourishing, using past experience as a guide.

Why is this relevant to emotion? Because every brain region that’s claimed to be a home of emotion in humans is a body-budgeting region within the interoceptive network. These regions, however, don’t react in emotion. They don’t react at all. They predict, intrinsically, to regulate your body budget. They issue predictions for sights, sounds, thoughts, memories, imagination, and, yes, emotions. The idea of an emotional brain region is an illusion caused by the outdated belief in a reactive brain.

Affect is the general sense of feeling that you experience throughout each day. It is not emotion but a much simpler feeling with two features. The first is how pleasant or unpleasant you feel, which scientists call valence. The pleasantness of the sun on your skin, the deliciousness of your favorite food, and the discomfort of a stomachache or a pinch are all examples of affective valence. The second feature of affect is how calm or agitated you feel, which is called arousal. The energized feeling of anticipating good news, the jittery feeling after drinking too much coffee, the fatigue after a long run, and the weariness from lack of sleep are examples of high and low arousal.

Interoception is a fundamental feature of the human nervous system, and why you experience these sensations as affect is one of the great mysteries of science. Interoception did not evolve for you to have feelings but to regulate your body budget. It helps your brain track your temperature, how much glucose you are using, whether you have any tissue damage, whether your heart is pounding, whether your muscles are stretching, and other bodily conditions, all at the same time. Your affective feelings of pleasure and displeasure, and calmness and agitation, are simple summaries of your budgetary state. Are you flush? Are you overdrawn? Do you need a deposit, and if so, how desperately?

When you experience affect without knowing the cause, you are more likely to treat affect as information about the world, rather than your experience of the world.

When you experience affect without knowing the cause, you are more likely to treat affect as information about the world, rather than your experience of the world. The psychologist Gerald L. Clore has spent decades performing clever experiments to better understand how people make decisions every day based on gut feelings. This phenomenon is called affective realism, because we experience supposed facts about the world that are created in part by our feelings

The sensations you feel from your body don’t always reflect the actual state of your body. That’s because familiar sensations like your heart beating in your chest, your lungs filling with air, and, most of all, the general pleasant, unpleasant, aroused, and quiescent sensations of affect are not really coming from inside your body. They are driven by simulations in your interoceptive network. In short, you feel what your brain believes. Affect primarily comes from prediction.

You might think that in everyday life, the things you see and hear influence what you feel, but it’s mostly the other way around: that what you feel alters your sight and hearing. Interoception in the moment is more influential to perception, and how you act, than the outside world is.

The bottom line is this: the human brain is anatomically structured so that no decision or action can be free of interoception and affect, no matter what fiction people tell themselves about how rational they are. Your bodily feeling right now will project forward to influence what you will feel and do in the future. It is an elegantly orchestrated, self-fulfilling prophecy, embodied within the architecture of your brain.

Concepts, Goals, and Words

My point is not to say, “You construct instances of emotion by categorization: isn’t that unique?” Rather, it’s to show that categorization constructs every perception, thought, memory, and other mental event that you experience, so of course you construct instances of emotion in the same manner. This is not effortful, conscious categorization, as when an entomologist pores over some new specimen of weevil, deciding whether it’s a member of the anthribidae or nemonychidae family. I’m speaking of the rapid, automatic categorization performed constantly by your brain, in every waking moment, in milliseconds, to predict and explain the sensory input that you encounter. Categorization is business as usual for your brain, and it explains how emotions are made without needing fingerprints.

Emotions are not reactions to the world; they are your constructions of the world.

How the Brain Makes Emotions

Emotions are meaning. They explain your interoceptive changes and corresponding affective feelings, in relation to the situation. They are a prescription for action. The brain systems that implement concepts, such as the interoceptive network and the control network, are the biology of meaning-making.

So, now you know how emotions are made in the brain. We predict and categorize. We regulate our body budgets, as any animal does, but wrap this regulation in purely mental concepts like “Happiness” and “Fear,” that we construct in the moment. We share these purely mental concepts with other adults, and we teach them to our children. We make a new kind of reality and live in it every day, mostly unaware that we are doing so.

Emotions as Social Reality

A sound, therefore, is not an event that is detected in the world. It is an experience constructed when the world interacts with a body that detects changes in air pressure, and a brain that can make those changes meaningful. Without a perceiver there is no sound, only physical reality.

Emotions are real, but real in the same manner of the sound of a tree falling, the experience of red, and the distinctions between flowers and weeds. They are all constructed in the brain of a perceiver.

Your muscle movements and bodily changes become functional as instances of emotion only when you categorize them that way, giving them new functions as experiences and perceptions. Without emotion concepts, these new functions don’t exist. There are only moving faces, beating hearts, circulating hormones, and so on, just as without color and sound concepts, “red” and the sound of a falling tree would not exist. There’d be only light and vibrations.

The distinction between “real in nature” versus “illusory” is a false dichotomy. Fear and anger are real to a group of people who agree that certain changes in the body, on the face, and so on, are meaningful as emotions. In other words, emotion concepts have social reality. They exist in your human mind that is conjured in your human brain, which is part of nature. The biological processes of categorization, which are rooted in physical reality and are observable in the brain and body, create socially real categories. Folk concepts like “fear” and “anger” are not mere words to be discarded from scientific thought but play a critical role in the story of how the brain creates emotion.

Make something up, give it a name, and you’ve created a concept. Teach your concept to others, and as long as they agree, you’ve created something real. How do we work this magic of creation? We categorize. We take things that exist in nature and impose new functions on them that go beyond their physical properties. Then we transmit these concepts to each other, wiring each other’s brains for the social world. This is the core of social reality.

Emotion categories, in my view, are made real through collective intentionality. To communicate to someone else that you feel angry, both of you need a shared understanding of “Anger.” If people agree that a particular constellation of facial actions and cardiovascular changes is anger in a given context, then it is so. You needn’t be explicitly aware of this agreement. You don’t even have to agree whether a particular instance is anger or not. You just have to agree in principle that anger exists with certain functions. At that point, people can transmit information about that concept among themselves so efficiently that anger seems inborn.

I am not saying emotions are illusions. They are real, but socially real in the manner of flowers and weeds. I’m not saying that everything is relative. If that were true, civilization would fall apart. I am also not saying that emotions are “just in your head.” That phrase trivializes the power of social reality. Money, reputation, laws, government, friendship, and all of our most fervent beliefs are also “just” in human minds, but people live and die for them. They are real because people agree that they’re real. But they, and emotions, exist only in the presence of human perceivers

This brings us to one of the most challenging ideas in this book: you need an emotion concept in order to experience or perceive the associated emotion. It’s a requirement. Without a concept for “Fear,” you cannot experience fear. Without a concept for “Sadness,” you cannot perceive sadness in another person. You could learn the necessary concept, or you could construct it in the moment through conceptual combination, but your brain must be able to make that concept and predict with it. Otherwise, you will be experientially blind to that emotion.

Emotion concepts like “Fear,” “Anger,” and “Happiness” are passed down from one generation to the next. This occurs not merely because we propagate our genes but because those genes allow each generation to wire the brains of the next one. Infants grow minds full of concepts as they learn the mores and values of their culture. This process goes by many names: Brain development. Language development. Socialization.

A New View of Human Nature

You are not a reactive animal, wired to respond to events in the world. When it comes to your experiences and perceptions, you are much more in the driver’s seat than you might think. You predict, construct, and act. You are an architect of your experience.

Your control network, you may recall, constantly shapes the course of your predictions and prediction error to help select among multiple actions, whether you experience yourself as in control or not. This network can only work with the concepts that you’ve got. So the question of responsibility becomes, Are you responsible for your concepts? Not all of them, certainly. When you’re a baby, you can’t choose the concepts that other people put into your head. But as an adult, you absolutely do have choices about what you expose yourself to and therefore what you learn, which creates the concepts that ultimately drive your actions, whether they feel willful or not. So “responsibility” means making deliberate choices to change your concepts.

Essentialism is the culprit that has made the classical view supremely difficult to set aside. It encourages people to believe that their senses reveal objective boundaries in nature. Happiness and sadness look and feel different, the argument goes, so they must have different essences in the brain. People are almost always unaware that they essentialize; they fail to see their own hands in motion as they carve dividing lines in the natural world.

Essentialism also appears to be an inherent part of our psychological makeup. Humans create categories by inventing purely mental similarities, as you learned in chapter 5, and we name those categories with words. That’s why a word like “pet” or “sadness” applies to a multitude of diverse instances. Words are an incredible achievement, but they are also a Faustian bargain for the human brain. On one hand, a word like “sadness,” when applied to a collection of varied perceptions, invites you to search for (or invent) some underlying sameness that transcends their noticeable differences. That is, the word “sadness” guides you to create an emotion concept, which is a good thing. But the word also invites you to believe in a reason for that sameness: some deep, unobservable, or even unknowable quality that is responsible for their equivalence, giving them their true identity. That is, words invite you to believe in an essence, and that process is conceivably the psychological origin of essentialism.

The very words that help us to learn concepts can also trick us into believing that their categories reflect firm boundaries in nature.

Plato’s essences of the mind are still around today, though their names have changed (and we’ve dispensed with the horses). Nowadays we call them perception, emotion, and cognition. Freud called them the id, the ego, and the superego. The psychologist and Nobel laureate Daniel Kahneman metaphorically calls them System 1 and System 2. (Kahneman is very careful to say it’s a metaphor, but many people seem to be ignoring him and essentializing Systems 1 and 2 as blobs in the brain.) The “triune brain” names them the reptilian brain, the limbic system, and the neocortex

The classical view often dismisses construction as saying everything is relative, as if the mind were merely a blank slate and biology can be disregarded. Construction blasts the classical view for ignoring the powerful effects of culture and justifying the status quo. In caricature, the classical view says “nature” and construction says “nurture,” and the result has been a wrestling match between straw men.

Modern neuroscience, however, has burned down both caricatures. We are not blank slates, and our children are not “Silly Putty” to be shaped this way and that, but neither is biology destiny.

Mastering Your Emotions

After attending to your body budget, the next best thing you can do for emotional health is to beef up your concepts, otherwise known as “becoming more emotionally intelligent.” People with a classical view mindset think about emotional intelligence as “detecting” other people’s emotions “accurately,” or experiencing happiness and avoiding sadness “at the right time.” With our new understanding of emotions, however, we can think about emotional intelligence in a new way. “Happiness” and “Sadness” are each populations of diverse instances. Therefore, emotional intelligence (EI) is about getting your brain to construct the most useful instance of the most useful emotion concept in a given situation. (And also when not to construct emotions but instances of some other concept.)

A key to EI is to gain new emotion concepts and hone your existing ones. There are many ways to gain new concepts: taking trips (even just a walk in the woods), reading books, watching movies, trying unfamiliar foods. Be a collector of experiences. Try on new perspectives the way you try on new clothing. These kinds of activities will provoke your brain to combine concepts to form new ones, changing your conceptual system proactively so you’ll predict and behave differently later.

Perhaps the easiest way to gain concepts is to learn new words. Learn as many new words as possible. Read books that are outside of your comfort zone, or listen to thought-provoking audio content like National Public Radio. Don’t be satisfied with “happy”: seek out and use more specific words like “ecstatic,” “blissful,” and “inspired.” Learn the difference between “discouraged” or “dejected” versus generically “sad.” As you build up the associated concepts, you’ll become able to construct your experiences more finely. And don’t limit yourself to words in your native language.

An emotionally intelligent person not only has lots of concepts but also knows which ones to use and when. Just like painters learn to see fine distinctions in colors, and wine lovers develop their palettes to experience tastes that non-experts cannot, you can practice categorizing like any other skill.

Keep track of your positive experiences each day. Can you find anything that can make you smile, even briefly? Each time you attend to positive things, you tweak your conceptual system, reinforcing concepts about those positive events and making them salient in your mental model of the world. It’s even better if you write about your experiences because, again, words lead to concept development, which will help you predict new moments to cultivate positivity.

What can you do to master your feelings in the moment? The simplest approach, believe it or not, is to move your body.

Another approach to mastering your emotions in the moment is to change your location or situation, which in turn can change your predictions.

The next big thing to try is recategorizing how you feel. With practice, you can learn to deconstruct an affective feeling into its mere physical sensations, rather than letting those sensations be a filter through which you view the world. You can dissolve anxiety into a fast-beating heart. Once you can deconstruct into physical sensations, then you can recategorize them in some other way, using your rich set of concepts. Perhaps that pounding in your chest is not anxiety but anticipation, or even excitement.

Deconstructing the self offers a new inspiration for how to become the master of your emotions. By tweaking your conceptual system and changing your predictions, you not only change your future experiences; you can actually change your “Self.”

When you are suffering from some ill or insult that has befallen you, ask yourself: Are you really in jeopardy here? Or is this so-called injury merely threatening the social reality of your self? The answer will help you recategorize your pounding heartbeat, the knot in the pit of your stomach, and your sweaty brow as purely physical sensations, leaving your worry, anger, and dejection to dissolve like an antacid tablet in water.

To improve at emotion perception, we must all give up the fiction that we know how other people feel. When you and a friend disagree about feelings, don’t assume that your friend is wrong like Dan’s ex-therapist did. Instead think, “We have a disagreement,” and engage your curiosity to learn your friend’s perspective. Being curious about your friend’s experience is more important than being right.

If you want someone else to know what you’re feeling, you need to transmit clear cues for the other person to predict effectively and for synchrony to occur. In the classical view of emotion, the responsibility is all on the perceiver’s end because emotions are supposedly displayed universally. In a construction mindset, you also bear the responsibility to be a good sender.

Emotion and Illness

My view is that some major illnesses considered distinct and “mental” are all rooted in a chronically unbalanced body budget and unbridled inflammation. We categorize and name them as different disorders, based on context, much like we categorize and name the same bodily changes as different emotions. If I’m correct, then questions like, “Why do anxiety and depression frequently co-occur?” are no longer mysteries because, like emotions, these illnesses do not have firm boundaries in nature.

Overall, the body sensations that are categorized as pain, stress, and emotions are fundamentally the same, even at the level of neurons in the brain and spinal cord. Distinguishing between pain, stress, and emotion is a form of emotional granularity.

Emotion and the Law

The idea that jurors can somehow detect remorse in a defendant, from his facial configurations or bodily movements or words, is steeped in the classical view, which assumes that emotions are universally expressed and recognized. The legal system assumes that remorse, like anger and other emotions, has a single, universal essence with a detectable fingerprint. However, remorse is an emotion category composed of many diverse instances, each one made for a specific situation.

Affective realism decimates the ideal of the impartial juror. Want to increase the likelihood of a conviction in a murder trial? Show the jury some gruesome photographic evidence. Tip their body budgets out of balance and chances are they’ll attribute their unpleasant affect to the defendant: “I feel bad, therefore you must have done something bad. You are a bad person.” Or permit family members of the deceased to describe in writing how the crime has hurt them, a practice known as a victim personal statement, and the jury will tend to recommend more severe punishments.

Is a Growling Dog Angry?

I think it’s best to assume all animals can experience affect.

My view, from evaluating the evidence, is that dogs don’t have human emotion concepts like anger, guilt, and jealousy.

If apes, dogs, and other animals don’t have the capacity to experience human emotions, why are there so many news stories about emotions being discovered in animals, even in insects? It all comes down to a subtle mistake that’s repeated over and over in science, and which is very difficult to detect and overcome.

Freezing is a behavior, whereas fear is a much more complex mental state. The scientists who believe they study fear learning are categorizing a freezing behavior as “Fear” and the underlying circuit for freezing as a fear circuit. Just as I categorized Cupcake the guinea pig as happy, when she herself couldn’t construct an experience of happiness, these scientists unknowingly apply their own emotion concepts, construct perceptions of fear, and attribute fear to the freezing rat. I call this general scientific mistake the mental inference fallacy.

In a nutshell, you can’t study fear by shocking rats unless at the outset you have defined “fear” circularly as “the freezing response of a shocked rat.”

From Brain to Mind: The New Frontier

A human brain can create many kinds of minds, yet all human minds do have some common ingredients. For millennia, scholars believed that the inevitable bits of the mind were essences, but they are not. The ingredients are three aspects of the mind that we’ve encountered in this book: affective realism, concepts, and social reality. They (and perhaps others) are inevitable and therefore universal, barring illness, based on the anatomy and function of the brain.

Affective realism, the phenomenon that you experience what you believe, is inevitable because of your wiring. The body-budgeting regions in your interoceptive network — your inner loudmouthed, mostly deaf scientist with a megaphone — are the most powerful predictors in your brain, and your primary sensory regions are eager listeners. Body-budget predictions laden with affect, not logic and reason, are the main drivers of your experience and behavior.

Anytime you have a gut feeling that you know something to be true, that’s affective realism. When you hear some news or read a story that you immediately believe, that’s affective realism too. Or if you are immediately dismissive of a message, or even dislike the messenger, that is also affective realism. We all like things that support our beliefs, and usually dislike things that violate those beliefs.

Affective realism is an inevitability, and yet you are not helpless against it. The best defense against affective realism is curiosity. I tell my students to be particularly mindful when you love or hate something you read. These feelings probably mean that the ideas you’ve read are firmly in your affective niche, so keep an open mind about them. Your affect is not evidence that the science is good or bad. The biologist Stuart Firestein in his lovely book Ignorance encourages curiosity as a way to learn about the world. Try to become comfortable with uncertainty, he suggests, finding pleasure in mystery, and being mindful enough to cultivate doubt. These practices will help you take a calm look at evidence that violates your own deeply held beliefs and experience the pleasure of the hunt for knowledge.

The second inevitability of the mind is that you have concepts, because the human brain is wired to construct a conceptual system. Concepts are vital to human survival, but we must also be careful with them because concepts open the door to essentialism. They encourage us to see things that aren’t present.

Concepts also encourage us not to see things that are present. One illusory stripe of a rainbow contains an infinite number of frequencies, but your concepts for “Red,” “Blue,” and other colors cause your brain to ignore the variability. Likewise, the frowny-faced stereotype of “Sadness” is a concept that downplays the great variation in that emotion category.

The third inevitability of the mind that we’ve discussed is social reality. When you are born, you can’t regulate your body budget by yourself — somebody else has to do it. In the process, your brain learns statistically, creates concepts, and wires itself to its environment, which is filled with other people who have structured their social world in particular ways. That social world becomes real to you as well.

When you create social reality but fail to realize it, the result is a mess. Many psychologists, for example, do not realize that every psychological concept is social reality. We debate the differences between “will power” and “tenacity” and “grit” as if they were each distinct in nature, rather than constructions shared through collective intentionality.

From these three inevitabilities of the mind, we see that construction teaches us to be skeptical. Your experiences are not a window into reality. Rather, your brain is wired to model your world, driven by what is relevant for your body budget, and then you experience that model as reality. Your moment-to-moment experience may feel like one discrete mental state followed by another, like beads on a string, but as you have learned in this book, your brain activity is continuous throughout intrinsic, core networks. Your experiences might seem to be triggered by the world outside the skull, but they’re formed in a storm of prediction and correction. Ironically, each of us has a brain that creates a mind that misunderstands itself.

What we experience as “certainty” — the feeling of knowing what is true about ourselves, each other, and the world around us — is an illusion that the brain manufactures to help us make it through each day. Giving up a bit of that certainty now and then is a good idea. For instance, we all think about ourselves and other people in terms of characteristics. He is “generous.” She is “loyal.” Your boss is “an asshole.” Our own sense of certainty tempts us to treat generosity, loyalty, and asshole-ness as if their essences actually live in those people, and as if they are detectable and measurable in objective terms. This not only determines our behavior toward them; we also feel justified in that behavior, even if the “generous” guy is just trying to suck up to you, the “loyal” woman is secretly self-serving, and your “asshole” boss has his mind on his sick kid at home. Certainty leads us to miss other explanations. I’m not saying that we are dumb or ill-equipped to grasp reality. I’m saying there is no single reality to grasp.