Willpower touches on nearly all aspects of healthy living: eating right, exercising, avoiding drugs and alcohol, studying more, working harder, spending less. Unsurprisingly, self-control has become a hot topic, both for scientists interested in understanding the roots of human behavior and for practitioners who want to help people live healthier lives. Roy F. Baumeister, PhD, a social psychologist at Florida State University, is one of the field’s leading researchers. His new book, “Willpower: Rediscovering the Greatest Human Strength,” co-authored with journalist John Tierney and released in September, describes surprising evidence that willpower is a limited resource subject to being used up.
Baumeister spoke to the Monitor about his research on self-control — where it comes from, how to get more of it and what psychologists still need to learn.
What drives you to better understand willpower?
The practical significance is enormous. Most of the problems that plague modern individuals in our society — addiction, overeating, crime, domestic violence, sexually transmitted diseases, prejudice, debt, unwanted pregnancy, educational failure, underperformance at school and work, lack of savings, failure to exercise — have some degree of selfcontrol failure as a central aspect.
Psychology has identified two main traits that seem to produce an immensely broad range of benefits: intelligence and self-control. Despite many decades of trying, psychology has not found much one can do to produce lasting increases in intelligence. But self-control can be strengthened. Therefore, self-control is a rare and powerful opportunity for psychology to make a palpable and highly beneficial difference in the lives of ordinary people.
You’ve found that willpower is a limited resource. Can you explain that?
Many studies have found that people perform relatively poorly on tests of self-control when they have engaged in a previous, seemingly unrelated act of self-control. For instance, in a study in my lab, we invited some students to eat fresh-baked chocolate-chip cookies, and asked others to resist the cookies and munch on radishes instead. Then we gave them impossible geometry puzzles to solve. The students who ate the cookies worked on the puzzles for 20 minutes, on average. But the students who had resisted the tempting cookies gave up after an average of eight minutes.
Such studies suggest that some willpower was used up by the first task, leaving less for the second. The pattern is opposite to what one would expect based on priming or activating a response mode. So we began to think that some kind of limited resource is at work: It gets depleted as people perform various acts of self-control. Over time, we have begun to link this resource to the folk notion of willpower. “Willpower” itself is a folk term, and the idea that we have some strength of character is a staple of folk psychology. Until recently, these folk notions had little resemblance to much in psychological theory — but our findings suggest that these notions are at least partly correct. However, in some respects, willpower depletion differs from traditional and folk ideas about willpower.
For example, we found that making decisions also seems to deplete one’s willpower. We found the same energy that is used for self-control is also used for making decisions. After making decisions, people perform worse at self-control. Conversely, after exerting selfcontrol, decision-making shifts toward simpler and easier processes. That can lead people to make poorer decisions, or to avoid making choices at all. I was a bit surprised that decisionmaking depleted the same resource as self-control. Intuitively it did not seem right, but on paper the hypothesis was a plausible extension. So we tested it, and have now demonstrated the effect repeatedly. Once we realized that the same resource is used for both self-regulation and decision-making, it became necessary to look for a broader framework. I think this common process is the psychological reality behind the folk notion of free will.
Can you walk us through a typical example of willpower depletion?
A dieter may easily avoid a doughnut for breakfast, but after a long day of making difficult decisions at work, he has a much harder time resisting that piece of cake for dessert. Another example might be losing your temper. Normally, you refrain from responding negatively to unpleasant things your romantic partner says. But if one day you’re especially depleted — maybe you’re trying to meet a stressful work deadline — and the person says precisely the wrong thing, you erupt and say the words you would have stifled if your self-control strength was at full capacity. What do you call this process? My collaborators and I use the term “ego depletion” to refer to the state of depleted willpower. Initially, we called it “regulatory depletion” because the first findings focused purely on acts of self-regulation. When it emerged that the same resource was also used for decision-making, we wanted a broader term that would suggest some core aspect of the self was depleted. We borrowed the term “ego” from Freudian theory because Freud had spoken about the self as being partly composed of energy and of processes involving energy.
How common are ego-depleting events?
Some people imagine that self-control or willpower is something you only use once in a while, such as when you are tempted to do something wrong. The opposite is true. Research indicates that the average person spends three to four hours a day resisting desires. Plus, self-control is used for other things as well, such as controlling thoughts and emotions, regulating task performance and making decisions. So most people use their willpower many times a day, all day.
You’ve found a physical basis for ego depletion?
Yes. My former student Matthew Gailliot, PhD, and I discovered the role of glucose in self-control, more or less by accident. While testing a different theory, we stumbled on the finding that people who got some food showed improvements in self-control afterward — regardless of whether they had enjoyed the food. This led us into several years of work aimed at finding out how glucose is related to self-control.
Glucose is the chemical in the bloodstream that carries energy to the brain, muscles and other organs and systems. In simple terms, glucose is fuel for the brain. Acts of self-control reduce blood glucose levels. Low levels of glucose predict poor performance on self-control tasks and tests. Replenishing glucose, even just with a glass of lemonade, improves self-control performance.
Aside from sipping lemonade, how can willpower be strengthened?
Quite a few studies in multiple labs have now shown that people can improve their self-control even as adults. As with a muscle, it gets stronger from regular exercise. So engaging in some extra self-control activities for a couple weeks produces improvement in self-control, even on tasks that have no relation to the exercise activities. The exercises can be arbitrary, such as using your left hand instead of your right hand to open doors and brush your teeth. Or they can be meaningful, such as working to manage money better and save more. The important thing is to practice overriding habitual ways of doing things and exerting deliberate control over your actions. Over time, that practice improves self-control.
Is there a lot left to learn about ego depletion?
I am constantly surprised and delighted to see how many different researchers are coming up with creative extensions, refinements and applications of these basic ideas about willpower. Within the last year, there have been studies on how willpower processes can help explain the troubles of students who worry about fitting in at college, how leaders may burn out, whether dogs get into fights, whether people keep their promises to romantic partners and more.
Our own work has recently found evidence for ego depletion outside the lab, which is a very important step. In an experience sampling study I worked on with Wilhelm Hofmann, PhD, a psychologist at the University of Chicago, participants wore beepers and reported their desires and relevant actions throughout their daily lives over the course of a week. We found that as people depleted their willpower, they became increasingly likely to give in to desires they might otherwise have resisted. This was true for all manner of desires: desires to sleep, to eat, to have sex, to play games, to spend money, to drink alcohol or smoke cigarettes, and on and on.
Another challenge for this research is to find out what it feels like to be ego-depleted. Efforts to develop a selfreport measure of the depleted state have not been very successful. A series of studies led by Kathleen Vohs, PhD, a psychologist at the University of Minnesota, has found that depletion makes all manner of emotions and desires be felt more strongly than usual — people with a depleted ego reported stronger reactions to both pleasant and unpleasant images, for example, and also seemed to experience physical pain more intensely. Depletion has no signature feeling, but it seems to be like turning up the volume on your life as a whole.
Kirsten Weir is a writer in Minneapolis.
Letters to the Editor
- Send us a letter