As Schultz monitored the activity within Julio’s brain, he saw a pattern emerge. Whenever Julio received his reward, his brain activity would spike in a manner that suggested he was experiencing happiness. A transcript of that neurological activity shows what it looks like when a monkey’s brain says, in essence, “I got a reward!”
Schultz took Julio through the same experiment again and again. And as the monkey became more and more practiced at the behavior—as touching the lever whenever Julio saw the shapes became a habit—Schultz saw a neurological change occur. The monkey’s brain begananticipating the blackberry juice. Schultz’s probes started recording the “I got a reward!” pattern the instant Julio saw the shapes on the screen, before the juice arrived:
In other words, the shapes on the monitor had become a cue not just for pulling a lever, but also for a pleasure response inside the monkey’s brain.
Then Schultz adjusted the experiment. Previously, Julio had received juice as soon as he touched the lever. Now, sometimes, the juice didn’t arrive at all, even if Julio performed correctly. Or it would arrive after a slight delay. Or it would be watered down until it was only half as sweet.
When that happened, Julio would get angry or become mopey. And within Julio’s brain, Schultz watched a new pattern emerge: craving. When Julio anticipated juice but didn’t receive it, a neurological pattern associated with desire and frustration erupted. When Julio saw the cue, he started anticipating a juice-fueled joy. But if the juice didn’t arrive, that joy became a craving that, if unsatisfied, drove Julio to anger or depression.
This, scientists say, is how habits emerge, and why they are so powerful: They create neurological cravings. Most of the time, these cravings emerge so gradually that we’re not really aware they exist. But as our brains start to associate certain cues (a doughnut box!) with certain rewards (yummy jelly!), a subconscious craving emerges. And so whenever we see the Dunkin’ Donuts container in the break room we start craving a donut—even if, just moments before, we weren’t hungry at all.
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Something similar, it turned out, was happening when people started using Pepsodent. About a decade after Pepsodent went on sale, competing toothpaste companies launched a massive project to figure out why it was such a success. Eventually they tripped over something interesting: the Pepsodent recipe.
Unlike other toothpastes of that period, Pepsodent contained citric acid, as well as doses of mint oil and other relatively exotic chemicals. Pepsodent’s inventor had used those ingredients to make his toothpaste taste minty and to make sure the paste wouldn’t become gluey as it sat on shelves.
But those chemicals had another, unanticipated effect as well: They’re irritants that create a tingling sensation on the tongue and gums.
When researchers at competing companies started interviewing customers, they found that people said that if they forgot to use Pepsodent, they realized their mistake because they missed that cool, tingling sensation in their mouths. They expected—they craved—that slight irritation. If it wasn’t there, their mouths didn’t feel clean.
Claude Hopkins, it turns out, wasn’t selling beautiful teeth. He was selling a sensation. Once people craved that cool tingling—once they equated it with cleanliness—brushing became a habit. Hopkins’ success was driven by the same factors that caused Julio the monkey to touch the lever.
As soon as other companies discovered what Hopkins was really selling, they started imitating him. Within a few decades, almost every toothpaste contained oils and chemicals that caused gums to tingle. Soon, Pepsodent started getting outsold. Even today, almost all toothpastes contain additives with the sole job of making your mouth tingle after you brush.
Studies indicate that anyone can use this basic formula to create habits of her or his own. Want to exercise more? Choose a cue, such as going to the gym as soon as you wake up, and a reward, such as a smoothie after each workout. Then think about that smoothie, or about the endorphin rush you’ll feel. Allow yourself to anticipate the reward. Eventually, that craving will make it easier to push through the gym doors every day.
Want to craft a new eating habit? When researchers affiliated with the National Weight Control Registry—a project involving more than 6,000 people who have lost more than 30 pounds—looked at the habits of successful dieters, they found that 78 percent of them ate breakfast every morning, a meal cued by a time of day. But most of the successful dieters alsoenvisioned a specific reward for sticking with their diet—a bikini they wanted to wear or the sense of pride they felt when they stepped on the scale each day. They focused on that craving when temptations arose, cultivated it into a mild obsession. And, researchers found, it crowded out temptations.
If you can identify the right cue and reward—and if you can create a sense of craving—you can establish almost any habit.
“Consumers need some kind of signal that a product is working,” Tracy Sinclair, who was a brand manager for Oral- B and Crest Kids Toothpaste, told me. “We can make toothpaste taste like anything—blueberries, green tea—and as long as it has a cool tingle, people feel like their mouth is clean. The tingling doesn’t make the toothpaste work any better. It just convinces people it’s doing the job.”
Excerpted from the book The Power of Habit by Charles Duhigg. Copyright © 2012 by Charles Duhigg. Reprinted by arrangement with Random House, an imprint of The Random House Publishing Group, a division of Random House Inc. All rights reserved.