How Emotions Are Made: The Secret Life of the Brain

by Lisa Feldman Barrett

So what are they, really? 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.5

This view, which I call the theory of constructed emotion, offers a very different interpretation

When Malloy’s voice caught in his throat, it did not trigger a brain circuit for sadness inside me, causing a distinctive set of bodily changes. Rather, I felt sadness in that moment because, having been raised in a certain culture, I learned long ago that “sadness” is something that may occur when certain bodily feelings coincide with terrible loss. Using bits and pieces of past experience, such as my knowledge of shootings and my previous sadness about them, my brain rapidly predicted what my body should do to cope with such tragedy. Its predictions caused my thumping heart, my flushed face, and the knots in...

My students and I had discovered a similar phenomenon for emotions, which I described as emotional granularity.2

I began wondering if I could teach people to improve their emotional granularity by coaching them to recognize their emotional states accurately. The key word here is “accurately.” How can a scientist tell if someone who says “I’m happy” or “I’m anxious” is accurate? Clearly, I needed some way to measure an emotion objectively and then compare it to what the person reports.

The “fingerprint” of an emotion is likewise assumed to be similar enough from one instance to the next, and in one person to the next, regardless of age, sex, personality, or culture. In a laboratory, scientists should be able to tell whether someone is sad or happy or anxious just by looking at physical measurements of a person’s face, body, and brain.

According to the classical view of emotion, our faces hold the key to assessing emotions objectively and accurately. A primary inspiration for this idea is Charles Darwin’s book The Expression of the Emotions in Man and Animals, where he claimed that emotions and their expressions were an ancient part of universal human nature. All people, everywhere in the world, are said to exhibit and recognize facial expressions of emotion without any training whatsoever.3

As it turns out, facial EMG presents a serious challenge to the classical view of emotion. In study after study, the muscle movements do not reliably indicate when someone is angry, sad, or fearful; they don’t form predictable fingerprints for each emotion. At best, facial EMG reveals that these movements distinguish pleasant versus unpleasant feeling. Even more damning, the facial movements recorded in these studies do not reliably match the posed photos created for the basic emotion method.10

Variation is the norm. Likewise, happiness, sadness, anger, and every other emotion you know is a diverse category, with widely varying facial movements.18

The media spreads them widely throughout the Western world. “Now, wait just a minute,” you might be thinking. “Is she saying that our culture has created these expressions, and we all have learned them?” Well . . . yes. And the classical view perpetuates these stereotypes as if they are authentic fingerprints of emotion.

Where emotions and the autonomic nervous system are concerned, four significant meta-analyses have been conducted in the last two decades, the largest of which covered more than 220 physiology studies and nearly 22,000 test subjects. None of these four meta-analyses found consistent and specific emotion fingerprints in the body. Instead, the body’s orchestra of internal organs can play many different symphonies during happiness, fear, and the rest.26

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.36

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.)

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.

Scientific evidence shows that what we see, hear, touch, taste, and smell are largely simulations of the world, not reactions to it. Forward-looking thinkers speculate that simulation is a common mechanism not only for perception but also for understanding language, feeling empathy, remembering, imagining, dreaming, and many other psychological phenomena. Our common sense might declare that thinking, perceiving, and dreaming are different mental events (at least to those of us in Western cultures), yet one general process describes them all. Simulation is the default mode for all mental activity. It also holds a key to unlocking the mystery of how the brain creates emotions.4

Every moment that you are alive, your brain uses concepts to simulate the outside world. Without concepts, you are experientially blind, as you were with the blobby bee. With concepts, your brain simulates so invisibly and automatically that vision, hearing, and your other senses seem like reflexes rather than constructions.

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?

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.8

In these cases of disgust, longing, and anxiety, the concept active in your brain is an emotion concept. As before, your brain makes meaning from your aching stomach, together with the sensations from the world around you, by constructing an instance of that concept. An instance of emotion. And that just might be how emotions are made.

theory of constructed emotion:9 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.

Emotions are not reactions to the world. You are not a passive receiver of sensory input but an active constructor of your emotions. From sensory input and past experience, your brain constructs meaning and prescribes action. If you didn’t have concepts that represent your past experience, all your sensory inputs would just be noise. You wouldn’t know what the sensations are, what caused them, nor how to behave to deal with them. With concepts, your brain makes meaning of sensation, and sometimes that meaning is an emotion.

Heart rate changes are inevitable; their emotional meaning is not. Other cultures can and do make other kinds of meaning from the same sensory input.12

Not every theory agrees on every assumption, but together they assert that emotions are made, not triggered; emotions are highly variable, without fingerprints; and emotions are not, in principle, distinct from cognitions and perceptions.14

The theory of constructed emotion incorporates elements of all three flavors of construction. From social construction, it acknowledges the importance of culture and concepts. From psychological construction, it considers emotions to be constructed by core systems in the brain and body. And from neuroconstruction, it adopts the idea that experience wires the brain.

After conducting hundreds of experiments in my lab, and reviewing thousands more by other researchers, I’ve come to a profoundly unintuitive conclusion shared by a growing number of scientists. Emotions do not shine forth from the face nor from the maelstrom of your body’s inner core. They don’t issue from a specific part of the brain. No scientific innovation will miraculously reveal a biological fingerprint of any emotion. That’s because our emotions aren’t built-in, waiting to be revealed. They are made. By us. We don’t recognize emotions or identify emotions: we construct our own emotional experiences, and our perceptions of others’ emotions, on the spot, as needed, through a complex interplay of systems. Human beings are not at the mercy of mythical emotion circuits buried deep within animalistic parts of our highly evolved brain: we are architects of our own experience.

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.

Your river of feelings might feel like it’s flowing over you, but actually you’re the river’s source.

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.4

The intrinsic activity in your brain is not random; it is structured by collections of neurons that consistently fire together, called intrinsic networks. These networks operate somewhat like sports teams. A team has a pool of players; at any given moment, some players are in the game and others sit on the bench, ready to jump in when needed. Likewise, an intrinsic network has a pool of available neurons. Each time the network does its job, different groupings of its neurons play (fire) in synchrony to fill all the necessary positions on the team. You might recognize this behavior as degeneracy, because different sets of neurons in the network are producing the same basic function. Intrinsic networks are considered one of neuroscience’s great discoveries of the past decade.5

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.6

But here, I’m focusing on predictions at a microscopic scale as millions of neurons talk to one another. These neural conversations try to anticipate every fragment of sight, sound, smell, taste, and touch that you will experience, and every action that you will take. These predictions are your brain’s best guesses of what’s going on in the world around you, and how to deal with it to keep you alive and well.8

prediction means that the neurons over here, in this part of your brain, tweak the neurons over there, in that part of your brain, without any need for a stimulus from the outside world. Intrinsic brain activity is millions and millions of nonstop predictions.

And right now, with each word that you read, your brain is predicting what the next word will be, based on probabilities from your lifetime of reading experience. In short, your experience right now was predicted by your brain a moment ago. Prediction is such a fundamental activity of the human brain that some scientists consider it the brain’s primary mode of operation.9

Predictions not only anticipate sensory input from outside the skull but explain it.

Once the prediction is confirmed by an actual apple, the prediction has, in effect, explained the visual sensations as being an apple.10

If your brain predicts perfectly—say, you predicted a McIntosh apple as you came upon a display of them—then the actual visual input of the apple, captured by your retina, carries no new information beyond the prediction. The visual input merely confirms the prediction is correct, so the input needn’t travel any further in the brain. The neurons in your visual cortex are already firing as they should be. This efficient, predictive process is your brain’s default way of navigating the world and making sense of it. It generates predictions to perceive and explain everything you see, hear, taste, smell, and touch.

Your brain also uses prediction to initiate your body’s movements, like reaching your arm out to pick up an apple or dashing away from a snake. These predictions occur before you have any conscious awareness or intent about moving your body. Neuroscientists...

It’s called an illusion because movement feels like a two-step process—decide, then move—when in fact your brain issues motor predictions to move your body well before you become aware of your intent to move.

One human retina transmits as much visual data as a fully loaded computer network connection in every waking moment; now multiply that by every sensory pathway you have.

Consider what this means: events in the world, such as a snake slithering at your feet, merely tune your predictions, roughly the way that your breathing is tuned by exercise. Right now, as you read these words and understand what they mean, each word barely perturbs your massive intrinsic activity, like a small stone skipping on a rolling ocean wave. In brain-imaging experiments, when we show photographs to test subjects or ask them to perform tasks, only a small portion of the signal we measure is due to the photos and tasks; most of the signal represents intrinsic activity. 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.14

Figure 4-1: Your brain contains complete maps of your visual field. One map is located in your primary visual cortex, known as V1. If your brain merely reacted to the light waves that hit your retina and traveled to primary visual cortex (V1) via your thalamus, then it would have many neurons to carry that visual information to V1. But it has far fewer than one would expect (top image), and ten times as many projections going in the other direction, carrying visual predictions from V1 to the thalamus (center image). Likewise, 90 percent of all connections coming into V1 (lower image) carry predictions from neurons in other parts of cortex. Only a small fraction carries visual input from the world.13

Prediction errors aren’t problems. They’re a normal part of the operating instructions of your brain as it takes in sensory input. Without prediction error, life would be a yawning bore. Nothing would be surprising or novel, and therefore your brain would never learn anything new.

Your brain’s colossal, ongoing storm of predictions and corrections can be thought of as billions of tiny droplets. Each little drop represents a certain wiring arrangement that I’ll call a prediction loop, shown in figure 4-2. This arrangement holds at many levels throughout your entire brain. Neurons participate in prediction loops with other neurons. Brain regions participate in prediction loops with other regions. Your multitudes of prediction loops run in a massive parallel process that continues nonstop for your whole life, creating the sights, sounds, smells, tastes, and touches that make up your experiences and dictate your actions.

outstretched arm. When prediction errors occur, the brain can resolve them in two general ways. The first, which we’ve just seen in my lame attempt to catch a baseball, is that the brain can be flexible and change the prediction.

The brain’s second alternative is to be stubborn and stick with the original prediction. It filters the sensory input so it’s consistent with the prediction. In this situation, I could be standing in a baseball field but daydreaming (predicting and simulating) as the ball sails toward me. Even though the ball is fully within my visual field, I don’t notice it until it thumps at my feet. Another example would be the food-filled diapers at my daughter’s disgusting foods birthday party: our guests’ prediction of a baby poo aroma dominated their actual sensory input of mashed carrots.17

In a sense, your brain is wired for delusion: through continual prediction, you experience a world of your own creation that is held in check by the sensory world. Once your predictions are correct enough, they not only create your perception and action but also explain the meaning of your sensations. This is your brain’s default mode.

From your brain’s point of view, locked inside the skull, your body is just another part of the world that it must explain.

Usually, you experience interoception only in general terms: those simple feelings of pleasure, displeasure, arousal, or calmness that I mentioned earlier. Sometimes, however, you experience moments of intense interoceptive sensations as emotions. That is a key element of the theory of constructed emotion. In every waking moment, your brain gives your sensations meaning. Some of those sensations are interoceptive sensations, and the resulting meaning can be an instance of emotion.23

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.24

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.26