How Emotions Are Made: The Secret Life of the Brain

by Lisa Feldman Barrett

Companies like Affectiva and Realeyes offer to help businesses detect their customers’ feelings through “emotion analytics.”

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 stomach. They directed me to cry, an action that would calm my nervous system. And they made the resulting sensations meaningful as an instance of sadness.

no matter what I know about emotions as a scientist, I experience them much as the classical view conceives them. My sadness felt like an instantly recognizable wave of bodily changes and feelings that overwhelmed me as a reaction to tragedy and loss. If I were not a scientist using experiments to reveal that emotions are in fact made and not triggered, I too would trust my immediate experience.

Why should you care which theory of emotion is correct? Because belief in the classical view affects your life in ways you might not realize. Think about the last time you went through airport security, where taciturn agents of the Transportation Security Administration (TSA) X-rayed your shoes and evaluated your likelihood as a terrorist threat. Not long ago, a training program called SPOT (Screening Passengers by Observation Techniques) taught those TSA agents to detect deception and assess risk based on facial and bodily movements, on the theory that such movements reveal your innermost feelings.

Now imagine that you’re in a doctor’s office, complaining of chest pressure and shortness of breath, which may be heart attack symptoms. If you’re a woman, you’re more likely to be diagnosed with anxiety and sent home, whereas if you’re a man, you’re more likely to be diagnosed with heart disease and receive lifesaving preventive treatment. As a result, women over age sixty-five die more frequently of heart attacks than men do. The perceptions of doctors, nurses, and the female patients themselves are shaped by classical view beliefs that they can detect emotions like anxiety, and that women are inherently more emotional than men . . . with fatal consequences.

The Gulf War in Iraq was launched, in part, because Saddam Hussein’s half-brother thought he could read the emotions of the American negotiators and informed Saddam that the United States wasn’t serious about attacking.

Physics moved from Isaac Newton’s intuitive ideas about time and space to Albert Einstein’s more relative ideas, and eventually to quantum mechanics.

In biology, scientists carved up the natural world into fixed species, each having an ideal form, until Charles Darwin introduced the concept of natural selection.

Scientific revolutions tend to emerge not from a sudden discovery but by a...

Numerous experiments showed that people feel depressed when they fail to live up to their own ideals, but when they fall short of a standard set by others, they feel anxious.

But this turns out to be suspect

My window was the unexpected realization that an emotion is not a thing but a category of instances, and any emotion category has tremendous variety.

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.

What we have been calling a fingerprint might just be a stereotype.

The amygdala was first linked to fear in the 1930s when two scientists, Heinrich Klüver and Paul C. Bucy, removed the temporal lobes of rhesus monkeys.

Brain regions like the amygdala are routinely important to emotion, but they are neither necessary nor sufficient for emotion.

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.

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.

every supposed emotional brain region has also been implicated in creating non-emotional events, such as thoughts and perceptions.

Overall, we found that no brain region contained the fingerprint for any single emotion.

a single emotion category involves different bodily responses, not a single, consistent response.

Brain circuitry operates by the many-to-one principle of degeneracy: instances of a single emotion category, such as fear, are handled by different brain patterns at different times and in different people. Conversely, the same neurons can participate in creating different mental states (one-to-many).

variation is the norm. Emotion fingerprin...

We must consider that an emotion word, like “anger,” does not refer to a specific response with a unique physical fingerprint but to a group of highly variable instances that are tied to specific situations. What we colloquially call emotions, such as anger, fear, and happiness, are better thought of as emotion categories, because each is a collection of diverse instances.

Some scientists, using techniques from artificial intelligence, can train a software program to recognize many, many brain scans of people experiencing different emotions (say, anger and fear). The program computes a statistical pattern that summarizes each emotion category and then—here’s the cool part—can actually analyze new scans and determine if they are closer to the summary pattern for anger or fear. This technique, called pattern classification, works so well that it’s sometimes called “neural mind-reading.”

The statistical pattern for fear is not an actual brain state, just an abstract summary of many instances of fear. These scientists are mistaking a mathematical average for the norm.

experiential blindness,

Your brain added stuff from the full photograph into its vast array of prior experiences and constructed the familiar object you now see in the blobs. Neurons in your visual cortex changed their firing to create lines that aren’t present, linking the blobs into a shape that isn’t physically there.

Your past experiences—from direct encounters, from photos, from movies and books—give meaning to your present sensations.

Your brain combined bits and pieces of knowledge of previous apples you’ve seen and tasted, and changed the firing of neurons in your sensory and motor regions to construct a mental instance of the concept “Apple.” Your brain simulated a nonexistent apple using sensory and motor neurons.

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.

Your bee-related simulations are rooted in your mental concept of what a “Bee” is. This concept not only includes information about the bee itself (what it looks and sounds like, how you act on it, what changes in your autonomic nervous system allow your action, etc.), but also information contained in other concepts related to bees (“Meadow,” “Flower,” “Honey,” “Sting,” “Pain,” etc.). All this information is integrated with your concept “Bee,” guiding how you simulate the bee in this particular context. So, a concept like “Bee” is actually a collection of neural patterns in your brain, representing your past experiences.

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.

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.

Philosophers have long proposed that your mind makes sense of your body in the world, from René Descartes in the seventeenth century to William James (considered the father of American psychology) in the nineteenth; as you will learn, however, neuroscience now shows us how this process—and much more—occurs in the brain to make an emotion on the spot. 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.

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.

Our challenge here is that the dynamics of the brain, and how emotions are made, do not follow a linear, cause-and-effect sort of story. (This challenge is common in science; for example, in quantum mechanics, the distinction between a cause and an effect is not meaningful.)

The theory of constructed emotion belongs to a broader scientific tradition called construction, which holds that your experiences and behaviors are created in the moment by biological processes within your brain and body. Construction is based on a very old set of ideas that date back to Ancient Greece, when the philosopher Heraclitus famously wrote, “No man ever steps in the same river twice,” because only a mind perceives an ever-changing river as a distinct body of water.

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.

An example would be whether or not Pluto is a planet, which is a decision not based in astrophysics but in culture. Spherical rocks in space are objectively real and come in various sizes, but the idea of a “Planet,” representing a particular combination of features of interest, is made up by people.

your brain’s interconnections are not inevitable consequences of your genes alone. We know today that experience is a contributing factor. Your genes turn on and off in different contexts, including the genes that shape your brain’s wiring. (Scientists call this phenomenon plasticity.) That means some of your synapses literally come into existence because other people talked to you or treated you in a certain way.

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.

There is no single difference between anger and fear, because there’s no single “Anger” and no single “Fear.” These ideas are inspired by William James, who wrote at length on the variability of emotional life, and by Charles Darwin’s revolutionary idea that a biological category, such as a species, is a population of unique individuals.

Therefore we ask how, not where, emotions are made.

An instance of fear has irreducible, emergent properties not found in the ingredients alone, such as unpleasantness (as your car skids out of control on a slippery highway) or pleasantness (on an undulating rollercoaster). You cannot reverse-engineer a recipe for an instance of fear from a feeling of fear.

“emotion,” because it could refer

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.

Infants who are four to eight months old, for example, can distinguish smiling faces from scowling faces. This ability, however, turned out not to be related to emotion per se. In those experiments, the posed faces for happiness showed teeth while those for anger did not, and that’s the cue that infants picked up on.

Infants are like AI! Picking up on the auxiliary cues