In evidence that stacking works, consider dental floss. Many of us clean our teeth regularly but fail to floss. To test whether stacking increases flossing, researchers gave fifty British participants, who flossed on average only 1.5 times per month, information encourage them to do it more regularly.
Half of the participants were told to floss before they brushed at night, and half after they brushed. Note that only half of the participants were really stacking-using an existing automated response (brushing their teeth) as a cue for a new behavior (flossing). The other half, who first flossed and then brushed, had to remember, oh, yes, first I need to floss, before I brush. No automated cue.
Each day for four weeks, participants reported by text whether they flossed the night before. At the end of the month of reminders, they all flossed about twenty-four days on average. Most interesting is what they were all doing eight months later. Those who stacked, and flossed after they brushed, were still doing it about eleven days a month. For them, the new behavior was maintained by the existing habit. The group originally instructed to floss before they brushed ended up doing it only about once a week.
The little-known nineteenth-century French philosopher Félix Ravaisson was able to put this concept into concrete terms. He called it the double law of habit. Basically it means this: repetition strengthens our tendency to act, but it also weakens our sensation of that act. In other words, we habituate. It’s a deceptively complex process, and one that has power to sap force and meaning from our lives. We tend to keep doing things long after they have lost meaning for us. Yes, we can take advantage of that dynamic when we form new habits, as they lose their hard edges with repetition. But it’s a double-edged sword.
Habituation is one reason we lose interest in the material stuff we buy (thinking those things will finally make us happy). Certainly, you enjoyed sitting on your new couch the day it was delivered. And you got to show it off to your friends the next time they visited. But after that? You probably don’t notice it much now.
Imagine that you are participating in an auction that involves chocolate coins as a reward. You can bid on a lot containing five coins or on a mystery lot that contains either three or five coins— you won’t know which until after your bid is accepted. Logically, the lot with five coins is worth more.
But it wasn’t. Researchers at the University of Chicago staged just this auction and found that the average bid for the guaranteed five coin lots was $1.25. The average bid for the mystery lot was $1.89. When asked, participants said the uncertain auction was more exciting. It didn’t increase the actual value of the reward. It just made the game more fun. Participants paid more to play and said they wanted to participate in the auction again. (The secret, though, was getting caught up in the process. When participants planned their bid in advance, they preferred the certain reward.)
Psychologist Daniel Wegner and his colleagues devised an experiment to demonstrate the ironic effect of inhibiting our desires. Participants were instructed in a simple task-not thinking of a white bear. Who spends much time thinking of white bears, anyway? Participants sat alone in a lab room for five minutes and rang a bell every time they failed to suppress this thought. On average, they rang the bell about five times, almost once per minute. No surprise that our thoughts wander, even to forbidden topics, when we are alone and bored. What is interesting is what happened when the same participants later sat for five minutes trying to think of a white bear. After the suppression task, they rang the bell almost eight times. In contrast, participants instructed to try to think of a white bear for five minutes, but without the initial task of not doing so, rang the bell fewer than five times. It was as if the act of trying to suppress a thought gave it a special energy to emerge later. After the participants tried not to think about white bears, thoughts of them returned again and again. When rating their experience, participants who had initially suppressed thoughts of white bears reported feeling preoccupied with them.
All the efforts really did the trick. By the measures available, the educational program was a stunning success. In August 1991, right before the effort began, the National Cancer Institute and the produce growers conducted a telephone survey. About 8 percent of Americans were aware that they should eat at least five servings of produce daily. By 1997, the results were strikingly different. Thirty Nine percent of Americans knew that they should eat five servings a day. That’s a campaign that any political adviser would be proud of.
But this is not a book about campaigns and policy. This is a book about actually changing lives. So the real question is: What about people’s actual behavior? The program’s purpose was to get people to consume more fruits and vegetables. Did it?
At the beginning of the campaign, from 1988 to 1994, 11 percent of Americans ate five servings of fruit and vegetables daily. Almost a decade later … it was still 11 percent. The change in awareness was real; the change of behavior was nonexistent.