III.
As Larry Squire, the memory specialist, spent more and more time with Eugene, he became convinced his patient was somehow learning new behaviors. Images of Eugene’s brain showed that his basal ganglia had escaped injury from the viral encephalitis. Was it possible, the scientist wondered, that Eugene, even with severe brain damage, could still use the cue-routine-reward loop? Could this ancient neurological process explain how Eugene was able to walk around the block and find the jar of nuts in the kitchen?
To test if Eugene was forming new habits, Squire devised an experiment. He took sixteen different objects-bits of plastic and brightly colored pieces of toys-and glued them to cardboard rectangles. He then divided them into eight pairs: choice A and choice B. In each pairing, one piece of cardboard, chosen at random, had a sticker placed on the bottom that read “correct.” [25]
Eugene was seated at a table, given a pair of objects, and asked to choose one. Next, he was told to turn over his choice to see if there was a “correct” sticker underneath. This is a common way to measure memory. Since there are only sixteen objects, and they are always presented in the same eight pairings, most people can memorize which item is “correct” after a few rounds. Monkeys can memorize all the “correct” items after eight to ten days.
Eugene couldn’t remember any of the “correct” items, no matter how many times he did the test. He repeated the experiment twice a week for months, looking at forty pairings each day.
“Do you know why you are here today?” a researcher asked at the beginning of one session a few weeks into the experiment.
“I don’t think so,” Eugene said.
“I’m going to show you some objects. Do you know why?”
“Am I supposed to describe them to you, or tell you what they are used for?” Eugene couldn’t recollect the previous sessions at all.
But as the weeks passed, Eugene’s performance improved. After twenty-eight days of training, Eugene was choosing the “correct” object 85 percent of the time. At thirty-six days, he was right 95 percent of the time. After one test, Eugene looked at the researcher, bewildered by his success.
“How am I doing this?” he asked her.
“Tell me what is going on in your head,” the researcher said. “Do you say to yourself, ‘I remember seeing that one’?”
“No,” Eugene said. “It’s here somehow or another”-he pointed to his head-“and the hand goes for it.”
To Squire, however, it made perfect sense. Eugene was exposed to a cue: a pair of objects always presented in the same combination. There was a routine: He would choose one object and look to see if there was a sticker underneath, even if he had no idea why he felt compelled to turn the cardboard over. Then there was a reward: the satisfaction he received after finding a sticker proclaiming “correct.” Eventually, a habit loop emerged.
EUGENE’S HABIT LOOP
To make sure this pattern was, in fact, a habit, Squire conducted one more experiment. He took all sixteen items and put them in front of Eugene at the same time. He asked him to put all the “correct” objects into one pile.
Eugene had no idea where to begin. “Gosh sakes, how to remember this?” he asked. He reached for one object and started to turn it over. The experimenter stopped him. No, she explained. The task was to put the items in
“That’s just a habit, I think,” he said.
He couldn’t do it. The objects, when presented outside of the context of the habit loop, made no sense to him.
Here was the proof Squire was looking for. The experiments demonstrated that Eugene had the ability to form new habits, even when they involved tasks or objects he couldn’t remember for more than a few seconds. This explained how Eugene managed to go for a walk every morning. The cues-certain trees on corners or the placement of particular mailboxes-were consistent every time he went outside, so though he couldn’t recognize his house, his habits always guided him back to his front door. It also explained why Eugene would eat breakfast three or four times a day, even if he wasn’t hungry. As long as the right cues were present-such as his radio or the morning light through his windows-he automatically followed the script dictated by his basal ganglia.
What’s more, there were dozens of other habits in Eugene’s life that no one noticed until they started looking for them. Eugene’s daughter, for instance, would often stop by his house to say hello. She would talk to her father in the living room for a bit, then go into the kitchen to visit with her mother, and then leave, waving good-bye on her way out the door. Eugene, who had forgotten their earlier conversation by the time she left, would get angry-why was she leaving without chatting?-and then forget why he was upset. But the emotional habit had already started, and so his anger would persist, red hot and beyond his understanding, until it burned itself out.
“Sometimes he would bang the table or curse, and if you asked him why, he’d say ‘I don’t know, but I’m mad!’ ” Beverly told me. He would kick his chair, or snap at whoever came into the room. Then, a few minutes later, he would smile and talk about the weather. “It was like, once it started, he had to finish the frustration,” she said.
Squire’s new experiment also showed something else: that habits are surprisingly delicate. If Eugene’s cues changed the slightest bit, his habits fell apart. The few times he walked around the block, for instance, and something was different-the city was doing street repairs or a windstorm had blown branches all over the sidewalk-Eugene would get lost, no matter how close he was to home, until a kind neighbor showed him the way to his door. If his daughter stopped to chat with him for ten seconds before she walked out, his anger habit never emerged.
Squire’s experiments with Eugene revolutionized the scientific community’s understanding of how the brain works by proving, once and for all, that it’s possible to learn and make unconscious choices without remembering anything about the lesson or decision making. [26] Eugene showed that habits, as much as memory and reason, are at the root of how we behave. We might not remember the experiences that create our habits, but once they are lodged within our brains they influence how we act-often without our realization.
Since Squire’s first paper on Eugene’s habits was published, the science of habit formation has exploded into a major field of study. Researchers at Duke, Harvard, UCLA, Yale, USC, Princeton, the University of Pennsylvania, and at schools in the United Kingdom, Germany, and the Netherlands, as well as corporate scientists working for Procter & Gamble, Microsoft, Google, and hundreds of other companies are focused on understanding the neurology and psychology of habits, their strengths and weaknesses, and why they emerge and how they can be changed.
Researchers have learned that cues can be almost anything, from a visual trigger such as a candy bar or a television commercial to a certain place, a time of day, an emotion, a sequence of thoughts, or the company of particular people. Routines can be incredibly complex or fantastically simple (some habits, such as those related to emotions, are measured in milliseconds). Rewards can range from food or drugs that cause physical sensations, to emotional payoffs, such as the feelings of pride that accompany praise or self-congratulation.
And in almost every experiment, researchers have seen echoes of Squire’s discoveries with Eugene: Habits are powerful, but delicate. They can emerge outside our consciousness, or can be deliberately designed. They often occur without our permission, but can be reshaped by fiddling with their parts. They shape our lives far more than we realize-they are so strong, in fact, that they cause our brains to cling to them at the exclusion of all else, including common sense.
In one set of experiments, for example, researchers affiliated with the National Institute on Alcohol Abuse and Alcoholism trained mice to press levers in response to certain cues until the behavior became a habit. The mice were always rewarded with food. Then, the scientists poisoned the food so that it made the
