The Power of Habit: Chapter 2 Summary & Analysis

Early in the 20th century, the inventor of a minty new toothpaste called “Pepsodent” called up the wealthy advertising executive Claude C. Hopkins to ask for help designing a marketing campaign. Hopkins was famous for his outlandish claims promoting products like Palmolive soap and Quaker Oats. He also wrote an influential set of rules for getting consumers to develop new habits. But he wasn’t interested in Pepsodent because almost nobody in the U.S. brushed their teeth. But his inventor friend eventually convinced him to give Pepsodent a shot.

Hopkins’s secret to selling Pepsodent was creating a craving. He always looked for a “trigger” that would get consumers to use products. After learning about the harmless natural film that builds up on the teeth, he started putting up ads that told people to run their tongue across their teeth and feel the dirty film—which Pepsodent would remove. The cue was the film, the routine was tooth-brushing, and the reward was a cleaner, more beautiful smile.

In three weeks, Pepsodent was sold out. A few years later, Pepsodent was selling all around the world, and most Americans were regularly brushing their teeth. Hopkins’s ad campaign succeeded because he followed two basic rules: he found a straightforward, basic cue and “clearly define[d] the rewards.” These two rules are the keys to advertising and habit formation today. But there’s also one more rule.

In 1996, scientists and marketers at Proctor & Gamble were struggling to plan an ad campaign for a new smell-neutralizing spray based on the compound HPBCD. It was called Febreze. Drake Stimson, a former Wall Street mathematician, led the marketing campaign. When they test-marketed their product in Phoenix, they met a park ranger whose job was to capture skunks. As a result, everything in her house smelled like skunk. She said that Febreze changed her life. Stimson realized that Febreze could be a way for people to eliminate “embarrassing smells,” and his team designed ads that showed Febreze getting rid of cigarette and pet odors.

But the ads didn’t work. Febreze barely sold—even people who received free samples never used it. Drake Stimson almost got fired. But then Proctor & Gamble agreed to hire more consumer psychologists and give the campaign one more try. They visited another Phoenix woman’s home that stunk horribly like cats. But the woman couldn’t smell it. They realized that this was the problem: people usually get used to the bad smells they live with, to the point that they can’t smell them anymore. Therefore, they never made a habit of using Febreze. This left Stimson’s team with a serious problem: if people with stinky homes wouldn’t buy Febreze, who would?

While studying monkeys’ brains in the 1980s, the Cambridge professor Wolfram Schultz noticed that some monkeys liked apple juice, while others liked grape juice. He made a monkey named Julio play a game: he had to press a lever whenever a shape appeared on a screen. If he did, he got blackberry juice as a reward. At first, Julio’s brain activity spiked whenever he got the juice. Over time, however, it started to spike as soon as he saw the shapes, well before he got the juice. In other words, Julio started to anticipate his reward.

Then, Wolfram Schultz changed the experiment so that Julio only sometimes got juice. Whenever he pushed the lever but didn’t get his juice, Julio started responding with anger or depression. He was craving the juice. When monkeys in the same experiment had the opportunity to leave and eat food or play with other monkeys, they tended to do so—unless they had already started to develop cravings, in which case they kept pressing the lever indefinitely, like a gambler at a slot machine.

Wolfram Schultz’s experiment showed that habits’ power comes from their ability to build cravings over time, as they cause individuals to associate specific cues with specific rewards. For instance, over time, Julio started to immediately crave the juice as soon as he saw the cue (the shapes on the screen). Similarly, smokers start craving nicotine as soon as they see a pack of cigarettes, and people start anticipating opening their email as soon as they hear a notification sound. When particularly strong, craving can lead to addiction. But it’s still possible to overpower.

Physical exercise provides a good example of the relationship between craving and habit. A New Mexico State University study showed that most habitual exercisers keep going because they crave the endorphins and the feeling of accomplishment that working out gives them. To build a lasting habit, people must create simple cues and clear rewards for themselves—but the cue also needs to make them start craving the reward in order to really work. Wolfram Schultz told Duhigg that cues, rewards, and cravings can even lead people to develop habits they don’t want (like snacking on their children’s chicken nuggets at dinner). But cues, rewards, and cravings are also the key to building good habits.

After their first marketing campaign for Febreze failed, Drake Stimson and his team started desperately looking for other angles. Back in Phoenix, they visited a third woman. Even though she wasn’t trying to neutralize any specific smell, she sprayed Febreze in her house every day. She used it “as a final touch” to make things smell good every time she finished cleaning a room. She treated it as “a little mini-celebration.”

Back at the company headquarters, the marketing team analyzed video footage and realized that almost everyone looks happy after cleaning. They decided that Febreze should be the last part in a routine, a reward promising that “things will smell as nice as they look” after cleaning. Surely enough, consumers started craving the smell of Febreze, and sales skyrocketed. This again showed that simply creating cues and rewards wasn’t enough—ads also needed to create cravings. This is the third element that Claude C. Hopkins forgot about.

Despite his wild popularity, Claude C. Hopkins never identified the value of cravings. But this was the real reason he sold so much toothpaste. In reality, dozens of toothpaste companies besides Pepsodent had already promised to remove the film and reveal a beautiful smile in their advertisement. But Pepsodent contained chemicals like mint oil and citric acid, which left “a cool, tingling sensation” in people’s mouths after they used it. This created a craving. Over time, other companies copied Pepsodent, and today, most toothpastes contain cooling additives.

Duhigg concludes that cravings are the key to building habits. They’re the reason why most people brush their teeth but don’t use sunscreen on a daily basis. Cravings are also why business make shampoo, laundry detergent, and toothpaste that foam up—something consumers apparently crave. If they want to build new habits, people have to learn how to spark new cravings first.