How Emotions Are Made: The Secret Life of the Brain

Barrett explains that each of us can feel pleasure or displeasure, a process called “interoception,” during which the brain makes sense of input from the blood, organs, tissues, and hormones. Simply by breathing and digesting, our bodies can produce pleasant, unpleasant, neutral, or jittery feelings. Barrett calls interoception “the origin of feeling” and considers it a core aspect of how we create emotions.

The author explains that scholars have long been underestimated and misunderstood the brain. Many have posited that the brain is a “reactive” organ that stays in a dormant state until an external event triggers it to respond. Barrett holds that this “intuitive” theory, which likens the brain to a muscle, is “misguided,” as the brain’s neurons are constantly active, even in the absence of external triggers. This continuous activity, which lasts from birth to death, is called “intrinsic brain activity” (58). It consists of neurons called “intrinsic networks,” which maintain bodily functions such as breathing and heartbeat. Intrinsic brain activity is responsible for subconscious dreaming, imaginative thinking, and daydreaming. Additionally, intrinsic brain activity creates all kinds of sensations, helping one experience “basic pleasant, unpleasant, calm and jittery feelings” (58).

The brain is wired to make predictions. For example, if you hear a loud bang, your brain automatically makes predictions about the source of the sound (e.g., a door slam, a balloon popping, or a gunshot) based on the context. Barrett explains that making predictions is a “fundamental activity of the human brain” (59) that helps us survive. The brain regularly makes predictive assumptions to correctly visualize things or prompt the appropriate bodily reaction. If the brain were reactive rather than predictive, it would require more calories to run and be less efficient. The brain’s predictive processes aren’t always correct; they can make what Barrett calls “predictive errors,” such as mistaking a stranger for a friend, yet can easily correct such errors and learn new information through them. She uses the example of catching a fly baseball to demonstrate the brain’s predictive powers and reiterates that the human brain isn’t simply a reactive machine. Barrett compares the brain to a scientist, as it constantly makes predictions or hypotheses based on its previous observations.

The author holds that to the brain, bodily functions are “just another part of the world it must explain” (66). To give meaning to a bodily sensation, such as a stomachache, the brain makes predictions about what it could mean. Barrett’s research discovered “interoceptive networks” in the brain, showing that interoception is a “whole-brain process” (67) similar to the brain’s other sensory networks (hearing, vision, etc.). She explains that, simply put, the interoceptive network has two parts. One is the “body-budgeting region” (67), which helps the body regulate the heart rate, breathing, cortisol, metabolism, and more. The body-budgeting region regulates these functions using predictions based on past experiences. The other part of the interoceptive network is the “primary interoceptive cortex” (68), which processes your body’s sensory information.

Barrett argues that these findings are highly relevant to understanding emotion, since each region of the brain that is supposedly in charge of a particular feeling is in fact a “body-budgeting region” (69). She calls the notion of reactive brain regions “outdated,” since these regions make predictions for “sights, sounds, thoughts, memories, imagination, and, yes, emotions” (69). These body-budgeting regions may adjust their predictions based on thoughts alone, without changes in physical activity. For example, if an authority figure approaches you, your brain may prompt your body to release cortisol, giving your body more glucose—and therefore more energy—for the interaction. Even simply imagining such interactions can prompt your body to construct emotions; many people spend about half their time “simulating,” which informs their emotional states.

The author introduces the term “affect,” which refers to one’s general daily state of mind and is informed by both “valence” (how pleasant or unpleasant one feels) and “arousal” (how calm or energized one is). Our affect has no “off” switch: Even when we sleep, our brains are creating a positive, negative, or neutral affect. A state of high arousal and unpleasant valence could combine to create feelings of upset, while a pleasant valence and low arousal would result in calm. Barrett explains that affective valence can play a large part in our decision-making; for example, job interviewers are more likely to rate candidates highly on sunny days, and police and military officers are more likely to mistake neutral objects as weapons during high-pressure situations.

Barrett notes that the brain-budgeting region is excellent at making predictions but slow to correct them. For example, you may release cortisol if you hear a rustle in the bushes while hiking, or you may not realize you’re full until 20 minutes after a meal. The author claims that this shows that many of our sensations don’t originate in our bodies but are products of our interoceptive network. She argues that while we think what we see and hear informs our feelings, our feelings can also inform what our brains see and hear. Although we’re able to think rationally, Barrett argues that our affect is in the “driver’s seat,” while our rational thinking is a “passenger.” Our struggle to overcome our emotions and implement rational thinking is especially obvious in business and finance, as our modern economy is based on the false assumption that people are rational economic actors. Barrett calls this theory a “neural fairy tale” (80) and argues that it contributed to banking crises and recessions. The author adds that people have become invested in this theory because imagining people as especially rational beings helps us differentiate ourselves from the rest of the animal kingdom.

The author compares all sensory information, from language to watching TV, to pieces of a “puzzle” that your brain must quickly solve. Barrett states that in this chapter she’ll explain how our brains are constantly “categorizing with concepts” (86) for all sensory experiences, including emotional ones. She defines a category as a collection of things that have been “grouped together as equivalent for some purpose,” while concepts are a “mental representation of a category” (86) that exists in our heads (86). For example, you can imagine the color red and associate it with a red rose.

Traditionally, scientists believed that the brain stored basic definitions to create “concepts” of different people and objects. For example, a concept of a car may be that it always has four wheels, doors, and windows, is made of metal, and requires fuel. However, this view, which neglects to explain how people understand variation within categories, was discarded in the 1970s. A new theory then emerged, which held that people develop general prototypes to create concepts in the brain that allowed for some variation between types. Barrett posits that prototypes seem like an appropriate way to conceptualize emotion but argues that in reality too much variability exists within how a given emotion is expressed for a prototype to be accurate. She believes that people construct emotion concepts spontaneously as needed and that emotion concepts are “remarkably malleable and context-dependent” (90). These concepts can also be “goal-based,” meaning that they share some kind of qualities in common that can help one achieve a specific goal. For example, one could join together things as diverse as a flyswatter, a car, a house, and a calm attitude into a category of things that help one avoid bug stings.

Building on this example, Barrett argues that emotions are also highly varied goal-based concepts. For example, happiness can present in various ways, such as calm contentment or joyful excitement. Empathizing with others requires shared emotional concepts; for example, if a friend were frightened by airplane turbulence, we couldn’t empathize with that experience by imagining the nervous thrill of a rollercoaster ride. The author raises the question of where emotion concepts originate, arguing that infants develop them within their first year. Babies’ brains are equipped with the ability for “statistical learning,” or the ability to recognize patterns, and begin categorizing information into concepts from birth. This helps babies develop their ability to use emotion concepts. Infants’ categorization includes interpreting speech, distinguishing sounds and words from each other, and using predictive reasoning to make educated guesses about the world. Babies can also make inferences about other people’s preferences when given some indication of what other people are thinking.

Barrett explains that while statistical learning helps explain the origin of emotion concepts, another crucial ingredient in their development is language. The author argues that one can’t develop a “purely mental concept” (97) without words. She refers to several scientific studies that demonstrated that infants remember images or categories accurately when given a word to associate with them. Therefore, by teaching children language, we’re giving them a “tool to expand reality” (99) and also laying the foundation for them to create emotion concepts. Barrett hypothesizes that infants and children lack inborn notions of different emotions but create them in association with the words they hear throughout their childhood. This explains how people can readily identify vastly different expressions of an emotion as one feeling. Barrett notes that different cultures have nuanced emotion words that aren’t always easily translatable into other languages but are readily understood and applied in their native cultures. She reiterates that “emotions are not your reactions to the world; they’re your constructions of the world” (104).

The author claims that people describe their emotions with varying degrees of “emotional granularity,” or specificity. Some people may have thousands of words in their “emotional lexicon,” while others have hundreds or only dozens. Studying how one’s emotion word knowledge may reflect or inform one’s emotional states is difficult. Alexithymia, a condition that affects about 10% of people, results in a poor ability to perceive or experience emotion. People with alexithymia tend to have difficulty learning and remembering emotion words; Barrett thinks this demonstrates the connection between language and emotion. Importantly, emotion concepts and categorizations are inherently linked to “body budgets” and inform how our bodies regulate our internal functions. Barrett concludes the chapter by revealing that she’ll next explore the biology of how the brain categorizes information.