Imagine yourself at the end of a really long, hard day. Let’s say it’s the most exhausting of days: moving day. You’re completely exhausted. Even your hair feels tired. Cooking is certainly out of the question. You don’t even have the energy to locate a pan, plate, and fork, much less put them to use. Clearly it’s going to be a take-out night.
Within a block of your new place are three restaurants. One is a little bistro with fresh salads and paninis. Another is a Chinese place; the greasy, salty smells emanating from within make the back of your mouth tingle. There’s also a cute mom-and-pop pizzeria where the locals enjoy cheesy slices twice the size of their faces. To which restaurant do you drag your tired, aching body? Which kind of cuisine would you prefer to enjoy on your new floor? By contrast, consider what your choice might be if the meal were after an afternoon spent relaxing in the backyard with a good book.
In case you haven’t noticed, on stressful days many of us give in to temptation and choose one of the less healthy alternatives. Chinese takeout and pizza are practically synonymous with moving day, conjuring up an image of a young, attractive, tired, but happy couple surrounded by cardboard boxes and eating chow mein out of the box with chopsticks. And we all remember the times college friends offered us pizza and beer in exchange for helping them move.
This mysterious connection between exhaustion and the consumption of junk food is not just a figment of your imagination. And it is the reason why so many diets die on the chopping block of stress and why people start smoking again after a crisis.
Let Us Eat Cake
The key to this mystery has to do with the struggle between the impulsive (or emotional) and the rational (or deliberative) parts of ourselves. This is not a new idea; many seminal books (and academic papers) throughout history have had something to say about the conflicts between desire and reason. We have Adam and Eve, tempted by the prospect of forbidden knowledge and that succulent fruit. There was Odysseus, who knew he’d be lured by the Sirens’ song and cleverly ordered his crew to tie him to the mast and fill their ears with wax to muffle the tantalizing call (that way, Odysseus could have it both ways—he could hear the song without worrying that the men would wreck the ship). And in one of the most tragic struggles between emotion and reason, Shakespeare’s Romeo and Juliet fell hard for each other, despite Friar Laurence’s warning that untamed passion only brings disaster.
In a fascinating demonstration of the tension between reason and desire, Baba Shiv (a professor at Stanford University) and Sasha Fedorikhin (a professor at Indiana University) examined the idea that people fall into temptation more frequently when the part of their brain that is in charge of deliberative thinking is otherwise occupied. To reduce participants’ ability to think effectively, Baba and Sasha did not remove parts of their brains (as animal researchers sometimes do), nor did they use magnetic pulses to disrupt thinking (though there are machines that can do that). Instead, they decided to tax their participants’ ability to think by piling on what psychologists call cognitive load. Simply put, they wanted to find out whether having a lot on one’s mind would leave less cognitive room for resisting temptation and make people more likely to succumb to it.
Baba and Sasha’s experiment went like this: they divided participants into two groups and asked members of one group to remember a two-digit number (something like, say, 35) and they asked members of the other group to remember a seven-digit number (say, 7581280). The participants were told that in order to get their payment for the experiment, they would have to repeat the number to another experimenter who was waiting for them in a second room at the other end of the corridor. And if they didn’t remember the number? No reward.
The participants lined up to take part in the experiment and were briefly shown either the two-digit number or the seven-digit number. With their numbers in mind, they each walked down the hall to the second room where they would be asked to recall the number. But on the way, they unexpectedly passed by a cart displaying pieces of rich, dark chocolate cake and bowls of colorful, healthy-looking fruit. As participants passed the cart, another experimenter told them that once they got to the second room and recited their number they could have one of the two snacks—but they had to make their decision right then, at the cart. The participants made their choice, received a slip of paper indicating their chosen snack, and off they went to the second room.
What decisions did participants make while laboring under more and less cognitive strain? Did the “Yum, cake!” impulse win the day, or did they select the healthy fruit salad (the well-reasoned choice)? As Baba and Sasha suspected, the answer depended in part on whether the participants were thinking about an easy-to-remember number or a hard one. Those breezing down the hall with a mere “35” on their minds chose the fruit much more frequently than those struggling with “7581280.” With their higher-level faculties preoccupied, the seven-digit group was less able to overturn their instinctive desires, and many of them ended up succumbing to the instantly gratifying chocolate cake.
The Tired Brain
Baba and Sasha’s experiment showed that when our deliberative reasoning ability is occupied, the impulsive system gains more control over our behavior. But the interplay between our ability to reason and our desires gets even more complicated when we think about what Roy Baumeister (a professor at Florida State University) coined “ego depletion.”
To understand ego depletion, imagine that you’re trying to lose a few extra pounds. One day at work, you are eyeing a cheese danish at the morning meeting, but you’re trying to be good, so you work very hard to resist the temptation and just sip your coffee instead. Later that day, you are craving fettuccine alfredo for lunch but you force yourself to order a garden salad with grilled chicken. An hour later, you want to knock off a little early since your boss is out, but you stop yourself and say, “No, I must finish this project.” In each of these instances your hedonic instincts prompt you toward pleasurable types of gratification, while your laudable self-control (or willpower) applies opposing force in an attempt to counteract these urges.
The basic idea behind ego depletion is that resisting temptation takes considerable effort and energy. Think of your willpower as a muscle. When we see fried chicken or a chocolate milkshake, our first reaction is an instinctive “Yum, want!” Then, as we try to overcome the desire, we expend a bit of energy. Each of the decisions we make to avoid temptation takes some degree of effort (like lifting a weight once), and we exhaust our willpower by using it over and over (like lifting a weight over and over). This means that after a long day of saying “no” to various and sundry temptations, our capacity for resisting them diminishes—until at some point we surrender and end up with a belly full of cheese danish, Oreos, french fries, or whatever it is that makes us salivate. This, of course, is a worrisome thought. After all, our days are increasingly full of decisions, along with a never-ending barrage of temptations. If our repeated attempts to control ourselves deplete our ability to do so, is it any wonder that we so often fail? Ego depletion also helps explain why our evenings are particularly filled with failed attempts at self-control—after a long day of working hard to be good, we get tired of it all. And as night falls, we are particularly likely to succumb to our desires (think of late-night snacking as the culmination of a day’s worth of resisting temptation).
WHEN JUDGES GET TIRED
In case you’ve got a parole hearing coming up, make sure it’s first thing in the morning or right after lunchtime. Why? According to a study by Shai Danziger (a professor at Tel Aviv University), Jonathan Levav (a professor at Stanford University), and Liora Avnaim-Pesso (a professor at Ben-Gurion University of the Negev), judges on parole boards tend to grant parole more frequently when they are most refreshed. Investigating a large set of parole rulings in Israel, the researchers found that parole boards were more likely to grant parole during their first cases of the day and just after their lunch breaks. Why? The default decision of parole boards is not to grant parole. But it seems that when the judges felt rejuvenated, which was first thing in the morning or after just having eaten and taken a break, they had an increased ability to override their standard decision, make a more effortful decision, and grant parole more frequently. But over the many difficult decisions of the day, as their cognitive burden was building up, they opted for the simpler, default decision of not granting parole.
I think that PhD students (a slightly different sort of prisoner) instinctively understand this mechanism, which is why they often bring doughnuts, muffins, and cookies to their dissertation proposals and defenses. Based on the results of the parole study, it is likely that their judges are more likely to grant them academic parole and let them start their own independent lives.
Testing the Moral Muscle
In the TV series Sex and the City, Samantha Jones (the blondest and most salacious one, for those not in the know) finds herself in a committed relationship. She begins eating compulsively and consequently gains weight. What’s interesting is the reason behind this baffling behavior. Samantha notices that her eating compulsion started when a good-looking man moved in next door—just the kind of man she would have gone after when she was single. She realizes that she’s using food as a bulwark against temptation: “I eat so I don’t cheat,” she explains to her friends. Fictional Samantha is depleted, just like a real person. She can’t resist all temptation, so she compromises by falling for food instead of promiscuity.
Sex and the City is no cinematic or psychological masterpiece, but it poses an interesting question: Might people who overtax themselves in one domain end up being less moral in others? Does depletion lead us to cheat? That is what Nicole Mead (a professor at Católica-Lisbon), Roy Baumeister, Francesca Gino, Maurice Schweitzer (a professor at the University of Pennsylvania), and I decided to check out. What would happen to real-life Samanthas who were depleted by one task and then given an opportunity to cheat on another? Would they cheat more? Less? Would they predict that they are more likely to succumb to temptation and therefore try to avoid the tempting situation altogether?
Our first experiment included several steps. First, we split our participants into two groups. We asked one group to write a short essay about what they had done the previous day without using the letters “x” and “z.” To get a feeling for this task, try it yourself: Take out a piece of paper, and in five or six lines, write a short synopsis of one of your favorite books, but don’t use the letters “x” and “z.” Note: you cannot simply omit the letters from the words—you must use words that do not contain an “x” or “z” (e.g., “bicycle”).
We called this the nondepleting condition because, as you can tell, it’s pretty easy to write an essay without using the letters “x” and “z.”
We asked the other group to do the same thing but told them not to use the letters “a” and “n.” To get a better grasp of how this version of the task is different, on another piece of paper, try writing a short synopsis of one of your favorite movies while not using any words that contain the letters “a” and “n.”
As you probably discovered from your experience with the second task, trying to tell a story without using “a” and “n” required our storytellers to constantly repress the words that naturally popped into their minds. You can’t write that the characters “went for a walk in the park” or “ran into each other at a restaurant.”
All of those little acts of repression add up to greater depletion.
Once our participants turned in their essays, we asked them to perform a separate task for a different study, which was the main focus of this experiment. The other task was our standard matrix test.
How did things turn out? In the two control conditions, we found that both the depleted and nondepleted folks showed an equal ability to solve the math problems—which means that depletion did not diminish their basic ability to do the math. But in the two shredder conditions (in which they could cheat), things went differently. Those who wrote essays without the letters “x” and “z” and later shredded their answers indulged in a little bit of cheating, claiming to solve about one extra matrix correctly. But the participants in the shredder condition who’d undergone the ordeal of writing essays without the letters “a” and “n” took the proverbial cake: they claimed to have correctly solved about three extra matrices. As it turned out, the more taxing and depleting the task, the more participants cheated.
What do these findings suggest? Generally speaking, if you wear down your willpower, you will have considerably more trouble regulating your desires, and that difficulty can wear down your honesty as well.
Dead Grannies
Over the course of many years of teaching, I’ve noticed that there typically seems to be a rash of deaths among students’ relatives at the end of the semester, and it happens mostly in the week before final exams and before papers are due. In an average semester, about 10 percent of my students come to me asking for an extension because someone has died—usually a grandmother. Of course I find it very sad and am always ready to sympathize with my students and give them more time to complete their assignments. But the question remains: what is it about the weeks before finals that is so dangerous to students’ relatives?
Most professors encounter the same puzzling phenomenon, and I’ll guess that we have come to suspect some kind of causal relationship between exams and sudden deaths among grandmothers. In fact, one intrepid researcher has successfully proven it. After collecting data over several years, Mike Adams (a professor of biology at Eastern Connecticut State University) has shown that grandmothers are ten times more likely to die before a midterm and nineteen times more likely to die before a final exam. Moreover, grandmothers of students who aren’t doing so well in class are at even higher risk—students who are failing are fifty times more likely to lose a grandmother compared with nonfailing students.
In a paper exploring this sad connection, Adams speculates that the phenomenon is due to intrafamilial dynamics, which is to say, students’ grandmothers care so much about their grandchildren that they worry themselves to death over the outcome of exams. This would indeed explain why fatalities occur more frequently as the stakes rise, especially in cases where a student’s academic future is in peril. With this finding in mind, it is rather clear that from a public policy perspective, grandmothers—particularly those of failing students—should be closely monitored for signs of ill health during the weeks before and during finals. Another recommendation is that their grandchildren, again particularly the ones who are not doing well in class, should not tell their grandmothers anything about the timing of the exams or how they are performing in class.
Though it is likely that intrafamilial dynamics cause this tragic turn of events, there is another possible explanation for the plague that seems to strike grandmothers twice a year. It may have something to do with students’ lack of preparation and their subsequent scramble to buy more time than with any real threat to the safety of those dear old women. If that is the case, we might want to ask why it is that students become so susceptible to “losing” their grandmothers (in e-mails to professors) at semesters’ end.
Perhaps at the end of the semester, the students become so depleted by the months of studying and burning the candle at both ends that they lose some of their morality and in the process also show disregard for their grandmothers’ lives. If the concentration it takes to remember a longer digit can send people running for chocolate cake, it’s not hard to imagine how dealing with months of cumulative material from several classes might lead students to fake a dead grandmother in order to ease the pressure (not that that’s an excuse for lying to one’s professors).
Just the same, to all grandmothers out there: take care of yourselves at finals time.
Red, Green, and Blue
We’ve learned that depletion takes away some of our reasoning powers and with them our ability to act morally.
Still, in real life we can choose to remove ourselves from situations that might tempt us to behave immorally. If we are even somewhat aware of our propensity to act dishonestly when depleted, we can take this into account and avoid temptation altogether. (For example, in the domain of dieting, avoiding temptation could mean that we decide not to shop for groceries when we’re starving.)
In our next experiment, our participants could choose whether or not to put themselves into a position that would tempt them to cheat in the first place. Once again, we wanted to create two groups: one depleted, the other not. This time, however, we used a different method of mental exhaustion called the Stroop task.
In this task, we presented participants with a table of color names containing five columns and fifteen rows (for a total of seventy-five words). The words in the table were color names—red, green, and blue—printed in one of these three colors and organized in no particular order. Once the list was in front of the participants, we asked them to say the color of each word on the list aloud. Their instructions were simple: “If a word is written in red ink, regardless of what the word is, you should say ‘red.’ If a word is written in green ink, regardless of what the word is, you should say ‘green.’ And so on. Do this as fast as you can. If at any point you make a mistake, please repeat the word until you get it right.”
For the participants in the nondepleting condition, the list of colors was structured such that the name of each color (e.g., green) was written in the same color of ink (green). The participants in the depleting condition were given the same instructions, but the list of words had one key difference—the ink color did not match the name of the color (for instance, the word “blue” would be printed in green ink, and the participants were asked to say “green”).
To try the nondepleting condition of this experiment yourself, go to the first Stroop task in the following table (or go to the online color version at http://danariely.com/stroop/) and time how long it takes you to say the colors of all the words in the “Congruent Color Words” list. When you are done, try the depleting condition by timing how long it takes you to say aloud the colors of all the words in the “Incongruent Color Words” list.
NONDEPLETING CONDITION
Congruent Color Words
DEPLETING CONDITION
Incongruent Color Words
How long did these two tasks take you? If you are like most of our participants, reading the congruent list (the nondepleting condition) probably took around sixty seconds, but reading the incongruent list (the depleting condition) was probably three to four times more difficult and more time-consuming.
Somewhat ironically, the difficulty of naming the colors in the mismatched list stems from our skill as readers. For experienced readers, the meaning of the words we read comes to mind very quickly, creating an almost automatic reaction to say the corresponding word rather than the color of the ink. We see the green-colored word “red” and want to say “red!” But that is not what we are supposed to do in this task, so with some effort we suppress our initial response and instead name the color of the ink. You may also have noticed that as you keep at this task, you experience a sort of mental exhaustion resulting from the repeated suppression of your quick automatic responses in favor of the more controlled, effortful (and correct) responses.
After completing either the easy or the hard Stroop task, each participant was given the opportunity to take a multiple-choice quiz about the history of Florida State University. The test included questions such as “When was the school founded?” and “How many times did the football team play in the National Championship game between 1993 and 2001?” In total, the quiz included fifty questions, each with four possible answers, and participants were paid according to their performances. The participants were also told that once they finished answering all the questions, they would be given a bubble sheet so that they could transfer their answers from the quiz to the sheet, recycle the quiz itself, and submit only the bubble sheet for payment.
Imagine that you are a student in the condition with the opportunity to cheat. You have just finished the Stroop task (either the depleting or nondepleting version). You have been answering the quiz questions for the past few minutes, and the time allotted for the quiz is up. You walk up to the experimenter to pick up the bubble sheet so that you can dutifully transfer your answers.
“I’m sorry,” the experimenter says, pursing her lips in self-annoyance. “I’m almost out of bubble sheets! I only have one unmarked one, and one that has the answers premarked.” She tells you that she did her best to erase the marks on the used bubble sheet but the answers are still slightly visible. Annoyed with herself, she admits that she had hoped to administer one more test today after yours. She next turns to you and asks you a question: “Since you are the first among the last two participants of the day, you can choose which form you would like to use: the clean one or the premarked one.”
Of course you realize that taking the premarked bubble sheet would give you an edge if you decided to cheat. Do you take it? Maybe you take the premarked one out of altruism: you want to help the experimenter so that she won’t worry so much about it. Maybe you take the premarked one to cheat. Or maybe you think that taking the premarked one would tempt you to cheat, so you reject it because you want to be an honest, upstanding, moral person. Whichever you take, you transfer your answers to that bubble sheet, shred the original quiz, and give the bubble sheet back to the experimenter, who pays you accordingly.
Did the depleted participants recuse themselves from the tempting situation more often, or did they gravitate toward it? As it turned out, they were more likely than nondepleted participants to choose the sheet that tempted them to cheat. As a result of their depletion, they suffered a double whammy: they picked the premarked bubble sheet more frequently, and (as we saw in the previous experiment) they also cheated more when cheating was possible. When we looked at these two ways of cheating combined, we found that we paid the depleted participants 197 percent more than those who were not depleted.
Depletion in Everyday Life
Imagine you’re on a protein-and-vegetable diet and you go grocery shopping at the end of the day. You enter the supermarket, vaguely hungry, and detect the smell of warm bread wafting from the bakery. You see fresh pineapple on sale; although you adore it, it is off limits. You wheel your cart to the meat counter to buy some chicken. The crab cakes look good, but they have too many carbohydrates so you pass them by, too. You pick up lettuce and tomatoes for a salad, steeling yourself against the cheesy garlic croutons. You make it to the checkout counter and pay for your goods. You feel very good about yourself and your ability to resist temptation. Then, as you are safely out of the store and on the way to your car, you pass a school bake sale, and a cute little girl offers you a free brownie sample.
Now that you know what you know about depletion, you can predict what your past heroic attempts of resisting temptation may cause you to do: you will most likely give in and take a bite. Having tasted the delicious chocolate melting over your deprived taste buds, you can’t possibly walk away. You’re dying for more. So you buy enough brownies for a family of eight and end up eating half of them before you even get home.
NOW THINK ABOUT shopping malls. Say you need a new pair of walking shoes. As you make your way from Neiman Marcus to Sears across a vast expanse of gleaming commercial temptation, you see all kinds of things you want but don’t necessarily need. There’s that new grill set you’ve been drooling over, that faux-shearling coat for next winter, and the gold necklace for the party you will most likely attend on New Year’s Eve. Every enticing item you pass in the window and don’t buy is a crushed impulse, slowly whittling away at your reserve of willpower—making it much more likely that later in the day you will fall for temptation.
Being human and susceptible to temptation, we all suffer in this regard. When we make complex decisions throughout the day (and most decisions are more complex and taxing than naming the colors of mismatched words), we repeatedly find ourselves in circumstances that create a tug-of-war between impulse and reason. And when it comes to important decisions (health, marriage, and so on), we experience an even stronger struggle. Ironically, simple, everyday attempts to keep our impulses under control weaken our supply of self-control, thus making us more susceptible to temptation.
NOW THAT YOU know about the effects of depletion, how can you best confront life’s many temptations? Here’s one approach suggested by my friend Dan Silverman, an economist at the University of Michigan who was facing grave temptation on a daily basis.
Dan and I were colleagues at the Institute for Advanced Study at Princeton. The Institute is a lovely place for lucky researchers who can take a year off to do little else besides think, go for walks in the woods, and eat well. Every day, after we’d spent our mornings pondering life, science, art, and the reason for it all, we enjoyed a delectable lunch: say, duck breast served with polenta and glazed mushroom caps. Each lunch menu was accompanied by a wonderful dessert: ice cream, crème brûlée, New York cheesecake, triple chocolate cake with raspberry-crème filling. It was torturous, particularly for poor Dan, who had a powerful sweet tooth. Being a smart, rational, cholesterolically challenged economist, Dan wanted dessert, but he also understood that eating dessert daily is not advisable.
Dan thought about his problem for a while and concluded that when faced with temptation, a rational person should sometimes succumb. Why? Because by doing so, the rational person can keep him- or herself from becoming too depleted, remaining strong for whatever temptations the future may bring. So for Dan, who was very careful and concerned about future temptations, it was always carpe diem when it came to the daily dessert. And yes, along with Emre Ozdenoren and Steve Salant, Dan wrote an academic paper justifying this approach.
ON A MORE serious note, these experiments with depletion suggest that, in general, we would be well served to realize that we are continually tempted throughout the day and that our ability to fight this temptation weakens with time and accumulated resistance. If we’re really serious about losing weight, we should get rid of temptation by clearing our shelves and refrigerator of all the sugary, salty, fatty, and processed foods and acclimating to the taste of fresh produce. We should do this not only because we know that fried chicken and cake are bad for us but also because we know that exposing ourselves to such temptations throughout the day (and every time we open a cupboard or the refrigerator) makes it more difficult for us to fight off this and other temptations throughout the day.
Understanding depletion also means that (to the extent that we can) we should face the situations that require self-control—a particularly tedious assignment at work, for example—early in the day, before we are too depleted. This, of course, is not easy advice to follow because the commercial forces around us (bars, online shopping, Facebook, YouTube, online computer games, and so on) thrive on both temptation and depletion, which is why they are so successful.
Granted, we cannot avoid being exposed to all threats to our self-control. So is there any hope for us? Here’s one suggestion: once we realize that it is very hard to turn away when we face temptation, we can recognize that a better strategy is to walk away from the draw of desire before we are close enough to be snagged by it. Accepting this advice might not be easy, but the reality is that it is much easier to avoid temptation altogether rather than to overcome it when it sits lingering on the kitchen counter. And if we can’t quite do that, we can always try to work on our ability to fight temptation—perhaps by counting to a hundred, singing a song, or making an action plan and sticking to it. Doing any of these can help us build our arsenal of tricks for overcoming temptation so that we are better equipped to fight those urges in the future.
FINALLY, I SHOULD point out that sometimes depletion can be beneficial. Occasionally, we may feel that we are too much in control, dealing with too many restrictions, and that we’re not sufficiently free to follow our impulses. Perhaps sometimes, we just need to stop being responsible adults and let loose. So here’s a tip: next time you really want to let it all hang out and indulge your primal self, try depleting yourself first by writing a long autobiographical essay without using the letters “a” and “n.” Then go to a mall, try on different things, but buy nothing. Afterward, with all of this depletion weighing on you, place yourself in the tempting situation of your choice and let ’er rip. Just don’t use this trick too often.
AND IF YOU really need a more official-sounding excuse to succumb to temptation from time to time, just use Dan Silverman’s theory of rational self-indulgence as the ultimate license.