Previous
Prologue
Themes
and Colors
Key
LitCharts assigns a color and icon to each theme in The Power of Habit, which you can use to track the themes throughout the work.
Habits, Human Behavior, and Success
Habit Change and Personal Growth
Social Habits and Cultural Influence
The Moral Consequences of Habits
Summary
Analysis
In 1992, an elderly man named Eugene Pauly suddenly forgot who his son was. Then, he started vomiting and ran a fever of 105°F. In the emergency room, he deliriously attacked the nurses. He had viral encephalitis in his brain, which can be extremely dangerous. Fortunately for him, he survived with little damage, though scans showed strange gaps in his brain tissue. Still, within a few weeks, he was walking and talking like normal. But he couldn’t remember almost anything—not the day of the week, his doctor’s name, or who his friends were. Some days he had breakfast several times in a row because he kept forgetting that he’d already eaten.
Cases like Eugene Pauly’s illness are extremely valuable for neuroscience, because they can help researchers determine which parts of the brain contribute to certain abilities and behaviors. Pauly’s infection appears to have affected areas of the brain responsible for memory—but not areas responsible for unconscious abilities like walking and talking. His condition had the potential to help neuroscientists understand the way memories are formed, processed, and stored in the brain. But it also suggests that these memories are very different from the unconscious habits that he still performed.
Active
Themes
Eugene Pauly’s wife Beverly brought him to Larry Squire, a memory researcher in San Diego. Squire discovered that while Pauly couldn’t recommend basic information, he could still develop complex habits. Pauly’s brain scans showed that he had lost a small chunk of the middle of his brain. This looked similar to the brain of H.M., a patient who famously lost his memory after brain surgery. But unlike H.M., Eugene could maintain normal conversations and remember his early life. He just couldn’t retain new information for any longer than a minute. He didn’t even know where the rooms in his house were located—yet he could still easily find his way around it. Ultimately, Eugene would revolutionize science’s understanding of habits.
Pauly’s experience strongly suggests that habits depend on different parts of the brain than conscious memory. Somehow, the part of his brain responsible for habits could make use of the new information he learned, but the part responsible for conscious knowledge and decisions couldn’t. This has important implications for people who want to change their habits: they have to alter the right part of the brain. Learning new information can’t lead to forming new habits unless people learn to encode this information in a way that their unconscious, habitual brain can use.
Active
Themes
Beverly Pauly started taking Eugene on walks around the block twice a day. One day, he left the house on his own. Frightened that he would get lost, Beverly started frantically looking for him—but she found him back inside the house, watching TV. He had gone on his walk alone and brought back pinecones. He started taking walks every morning, but he could never remember where he had gone. Larry Squire wanted to investigate. He learned that Pauly couldn’t answer basic questions about his neighborhood—but he could guide someone around the neighborhood and back to his home. Clearly, Pauly was learning new information—the question was just how he did it, and where it was located in his brain.
At Massachusetts Institute of Technology, there are labs full of miniature surgery tables, where neurologists implant sensors in rats’ brains. The experiments done here are the key to understanding how Eugene Pauly formed new habits. In the 1990s, MIT researchers were studying the basal ganglia, a small, primitive structure at the very center of the brain that seemed important to habit formation. They learned that while rats wandered around a maze looking for chocolate, their brains were highly active—especially their basal ganglia. But when rats repeated the same maze many times, they eventually learned to do it faster, and their brains became less active—except for their basal ganglia, which kept working.
Active
Themes
Get the entire The Power of Habit LitChart as a printable PDF.
"My students can't get enough of your charts and their results have gone through the roof." -Graham S.
The rats learned to navigate the maze through chunking, or “convert[ing] a sequence of actions into an automatic routine.” This is the same process that people use to develop habits, including complex ones like starting a car and backing it out of a driveway. Habits help the brain save effort—which is why the brain tries to turn every routine into a habit if it can. By saving effort, the brain becomes more efficient and can pack more processing power into less space.
But saving effort can also be dangerous for the brain, which can miss important cues, like a car speeding into the street behind the driveway. Brain scans show that to compensate for this danger, the brain’s activity spikes right at the beginning and the end of a habit. At the beginning, the brain actively looks for a cue that can tell it which habit to use. Then, the brain powers down during the routine. Finally, at the end of the routine, the brain powers back up to evaluate what happened and receive a reward (whether mental, emotional, or physical). The brain gradually gets used to this three-part loop (cue, routine, reward). Over time, it even learns to expect and crave the reward.
Because the brain diverts its energy elsewhere during a routine, people tend to repeat the same routines automatically—unless they manage to deliberately replace those routines with new ones. While old habits never go away, new ones can still overtake them. Without the basal ganglia, people would be overwhelmed by basic everyday decisions. But the mind’s dependence on habits can also cause problems.
Active
Themes
Eugene Pauly’s basal ganglia were still intact, and Larry Squire wanted to test whether Pauly could still form habits. Squire gave Pauly a memory test over and over again for several weeks. In the test, there were eight pairs of objects; in each pair, one had a sticker saying “correct” on the bottom. Pauly couldn’t remember having done the test before, but after a few weeks, he was choosing almost all of the “correct” objects. But when Squire gave Pauly all sixteen objects and asked him to choose the eight “correct” ones, he couldn’t. This shows that he built a habit loop for the memory test, but he couldn’t actually remember which items were “correct.”
Active
Themes
Eugene Pauly could also form other habits—like his daily walks. He could also act out his anger, even when he couldn’t remember why he was angry. But when his cues subtly shifted, his habits stopped working. For instance, when there was construction in his neighborhood, he couldn’t find his way home on his walks. By studying Pauly, Larry Squire proved that people can unconsciously learn things and make decisions without remembering or understanding them.
Active
Themes
In the decades since Larry Squire published his research on Eugene Pauly, hundreds of scientists all around the world have started to study habits. Habits can involve all sorts of cues, routines, and rewards. They are “powerful, but delicate”—people can build and alter them either consciously or unintentionally, and they can often override common sense. For instance, scientists have shown that mice will continue pushing a lever to receive food even when they know the food is poisonous. This is similar to why many people frequently eat fast food, despite their intentions to avoid it. In fact, McDonald’s designs its restaurants and food to give customers consistent cues and immediate rewards.
Over time, Eugene Pauly settled into new habits. He went on walks, ate what he wanted, and spent most of his time watching the History Channel. But these habits became dangerous—he spent too long in front of the TV, didn’t stay on a healthy diet, and couldn’t remember to be careful on his walks as he aged. Beverly helped improved his diet, but it wasn’t enough to improve his health.
Active
Themes
When Eugene Pauly had a heart attack, he kept ripping off his chest monitors in the hospital. His daughter convinced him to keep them on by having the nurses repeatedly compliment him for sitting still. Later, he broke his hip, and after settling comfortably into the hospital for a few weeks, he died of a heart attack. He made a profound contribution to science, even if he never fully remembered it.
Active
Themes
