National Public Radio (NPR)


April 7, 2008 Monday

SHOW: Talk of the Nation  3:00 PM EST


Willpower Is Limited, But Can Grow with Practice




Do our brains contain a limited amount of willpower? If you're on a diet, is it harder to keep your emotions in check? If you're studying for an exam, will you backslide on the diet?

In an op-ed that appeared in the New York Times, Sandra Aamodt and Sam Wang argued that willpower is a limited resource best applied to one behavior at a time. So, has your willpower been tested lately? Did you have to prioritize one area and abandon another? Call us with your story: 800-989-8255. You can also e-mail us: You can also join the conversation on our blog at

And Sam Wang joins us now. He's an associate professor of molecular biology and neuroscience at Princeton University, and co-author of the New York Times op- ed: "Tighten Your Belt, Strengthen Your Mind," with us today from the studios at Princeton.

Nice to have you on the program.

Dr. SAM WANG (Associate Professor, Molecular Biology and Neuroscience, Princeton University; Co-Author, Tightens Your Belt, Strengthen Your Mind): Nice to be here. Thanks very much.

CONAN: And willpower, is this an element of character or is this something that we store up on our brains?

Dr. WANG: Well, willpower is this thing that we talk about in everyday life as being a thing that we exercise when we refuse a candy or when we control ourselves in an awkward situation. But what's interesting is that psychologists have recently found in the last few years increasing evidence that willpower is a thing that you can measure and it's a thing that can run out. And it's something that's generated by the brain like all our mental processes.

CONAN: So there's a finite supply of willpower?

Dr. WANG: There is a finite supply of willpower. Psychologists like to call it self-regulation, and when you run out, they like to call it by the phrase ego depletion.

CONAN: Ego depletion.

(Soundbite of laughter)

Dr. WANG: That's the phrase.

CONAN: There's been a few times in my life where - ego depletion. I'll bear that in mind.

(Soundbite of laughter)

CONAN: So, what the effect of this, you argue, is that, in fact, if you're - I don't know - trying to convince yourself to go out and run five miles every day that it might not be the greatest idea to start studying for a big exam at the same time.

Dr. WANG: Well, studies have shown that very different kinds of tasks draw on this one reserve, and it could be going out on the run. It could be trying to impress someone in a job interview. It could be refusing that extra helping. And all those appear to occlude one another. So, if you do one then you have a little bit less oomph to do the other.

CONAN: But this flies in the face of all of those people who said, wait a minute, if you can learn a little discipline, a little - enforce a little willpower, well, it spreads from one thing to another and you can benefit your entire life.

Dr. WANG: No, I think it's - I don't think it's different from that at all because experiences can change the brain, and that's a general area called neuroplasticity. And I think - and something that's been observed is that this reserve of willpower - let's just call it willpower - can be exercised. And so, you can exercise it like a muscle. And so, for instance, people who undertaken exercise program for several weeks get better at staying on a diet. And so, you can exercise it.

CONAN: And is there any way that we could measure our willpower tank and see how we're doing?

Dr. WANG: Measure your willpower tank. Well, people had done this in the laboratory and you'd have to - so one kind of study that people have done, say, some college students who are always up for this kind of thing were given a puzzle to solve and they weren't told that the puzzle was impossible. And what psychologists measured was how long they spent working on this puzzle. Now, on average, they spent 20 hours - 20 minutes working on it. And so, I guess you could do something like that.

CONAN: Hmm. And build up your - that muscle, if you will.

Dr. WANG: Yeah. Maybe the amount of time that was spent working on a hard puzzle before you give up.

CONAN: Our guest is Sam Wang, an associate professor of molecular biology and neuroscience at Princeton. If you'd like to join us: 800-989-8255. E-mail:

Have you exercised your willpower muscle of late? How have you prioritized the uses of that finite supply of willpower? 800-989-8255. E-mail:

Farah(ph) joins us. Farah, calling from Phoenix, Arizona.

FARAH (Caller): Hi.

CONAN: Hi, Farah.

Dr. WANG: Hi, Farah.

FARAH: Hi. I'm a kind of embarrassed actually to tell you this, but I - for once, I gave up sweet, which I thought is so embarrassing - but I also tried to give up gossip blogs. And...

Dr. WANG: Gossip blogs?

FARAH: Yeah. Gossip blogs. They (unintelligible) health and things like that. And I could...

(Soundbite of laughter)

FARAH: I quit the sweets, but as soon as I tried to do the gossip blogs, I just could not. I couldn't it. And so, I rewarded myself for not eating sweets by reading the gossips blogs.

CONAN: So, you could pass on the rocky road but TMZ, you were there.

(Soundbite of laughter)

FARAH: I'm there. I couldn't help it.

(Soundbite of laughter)

CONAN: And so, is this a classic example, do you think, Sam?

Dr. WANG: I think it's - I think that's a good example. The thing is different activities reward us to different extents. And the brain has different reward mechanisms. And so, we wrote in our book "Welcome To Your Brain" that the brain has systems for rewarding you. In your case, Farah, maybe the thing that really rewards you is social information like what's happening with, I don't know, what ever your favorite gossip story is.

(Soundbite of laughter)

FARAH: Yeah. Angelina Jolie.

CONAN: Are they married? Is she - anyway.

(Soundbite of laughter)

CONAN: Farah, thanks very much for the call and you're going to run up - write up and buy a big dish of ice cream and a copy of Us magazine.

FARAH: Exactly, Us Weekly (unintelligible).

Dr. WANG: Just do one or the other, try it out.

CONAN: One or the other. Thanks very much and good luck, Farah. Bye-bye.

Let's see if we could go to - this is - excuse me, five - Ciara(ph). Ciara, with us in Sacramento.

CIARA (Caller): Yes. I have - I'm obsessive-compulsive, and I wonder if we either have a different mechanism or a different capacity. Because I went on a medical fast a number of years ago, 300 calories a day plus...

Dr. WANG: Three hundred calories a day?

CIARA: Yes, they don't do that anymore.

CONAN: Ah, good.

CIARA: Yeah, really.

Dr. WANG: Wow.

CIARA: It was, well and...

CONAN: Well, you could pick up 300 calories walking pass a bakery.

(Soundbite of laughter)

CIARA: Oh, no. But I finished my master's degree at the same time. In fact, the day that I defended my thesis was the first day that I hadn't lost any weight, and I was more upset about that than I was proud about having the thesis accepted.

CONAN: So, Sam Wang, she's talking about OCD, obsessive-compulsive disorder. Might this change the equation somewhat?

Dr. WANG: I think it does, because obsessive-compulsive disorder is not all that terribly well understood, but it, you know, as Ciara knows, it's the perseveration of an activity over and over again. And that would be something, which the act of willpower then would be to decide not to do something.

And so, that's an unusual situation. Did you use your OCD to write your thesis, Ciara?

CIARA: Well, it got it the - I didn't, you know, I'm usually not aware of it unless I get ridiculous about repeating things and it get to my way. But it was just - it had to be done and so, I just ground my teeth and did it.

Mr. WANG: Well...

CIARA: But it had never occurred to me before. I've never purged this theory that you can only, you know, dream I got so much drive...

CONAN: Willpower.

CIARA: Willpower.

Dr. WANG: Yeah. Well, these appear to the best of anyone's knowledge. These appear to draw on different mental resources. And so, when people talk about ego depletion or self-regulation, those are probably mechanisms that are in the front of the brain in the prefrontal cortex and in another part of the brain called the anterior cinguli. And obsessive-compulsive disorder is - as I said, it's not really well understood, but it appears to draw on other brain regions. And the treatments, to my knowledge, that people give for OCD are not the kinds of things that are known to affect willpower. So, that's something different. That's probably your brain's reward system.

CONAN: Ciara, thanks very much for the call and congratulations on the master's degree.

Dr. WANG: Yes, congratulations.

CIARA: Thanks.

CONAN: Let's see if we can go now to Alex(ph). Alex, calling us from Charlotte, North Carolina.

ALEX (Caller): Hi, Neal, how was your day?

CONAN: Well, I'm doing very well. Thank you.

ALEX: I'm not so sure I completely agree that the will is a finite resource. I feel that every individual choice and decision we make is made in that moment. And I think that one of the reasons that I see some people who decide to either to do something or not to do something, the caving in to the desire, it usually have something to do with the pain that's involve with either choosing not to do something or choosing to do something.

And I think that maybe we live in a time where we just really can't deal with any discomfort at all. And that's what, you know, that's what we say, well, my willpower caved in, so I went and grabbed a cigarette or I went and had a doughnut. No, not really. It's just the pain of not having that or the pain of desiring something caused us to cave in, because we're really pleasure seeking entities.

Dr. WANG: That's an interesting point that Alex has made. In modern times, you can of course have whatever you want, in many case, is on demand, and that changes the formula about what constitutes willpower. So we were talking about a very specific controlled situation of being faced with as situation where you have to control yourself.

And now, moral decision making, emotional decision making - these are things that call on all your brain's resources. And there's much more to making decisions than just this one thing that's been studied in the lab in isolation.

PATRICK: Mm-hmm. I see. Well, I'd like - well, a great show, and let's all have more willpower.

(Soundbite of laughter)

CONAN: To exercise that most (unintelligible).

PATRICK: That's right.

CONAN: Thanks very much. Let's go now to Tony(ph). Tony's on the line in San Francisco.

TONY (Caller): Hi, there. I was wondering if your study had any implications on the treatment of addiction.

Dr. WANG: On the treatment of addiction - oh, that's interesting. Well, Tony let's see. So, first, it was a - these are studies done by psychologist Roy Baumeister. And we - what we did is we just synthesized all of their work and we put it together into something that would be helpful for people's everyday lives.

CONAN: And in English.

Dr. WANG: In English, yeah, that's right. It turn outs - actually it's a bit of work going through these technical articles and making sense out of them.

TONY: But perhaps (unintelligible) in work with it later.

Dr. WANG: So, for addiction, that's an interesting question. Addiction is - you mean, for instance, to something, like, say, cocaine or alcohol that kind of addiction?

TONY: Right.

Dr. WANG: Yeah. Those kinds of addiction induce chemical changes in the brain, and that's a thing that's not all that well understood. But those, again, act on these mechanisms in the brain for reward. And there - it's sort of a different part of the brain than willpower. Now, obviously, you have to exert your willpower in order to say no to whatever it is that's being offered to, whether it is a gossip blog or, you know, an illicit drug.

And so, certainly willpower training can help you in this regard. But there are other things that are in chemical in nature that are out of reach with this kind of training.

TONY: Okay, thanks a lot.

CONAN: Thanks for the call.

Dr. WANG: Thanks, Tony.

CONAN: Sam Wang is co-author - along with Sandra Aamodt, the editor in chief of Nature Neuroscience - of the book "Welcome To Your Brain: Why You Lose Your Car Keys, But Never Forget How to Drive and Other Puzzles of Everyday Life." We're talking to them about an op-ed that appeared in the New York Times, called "Tighten Your Belt, Strengthen Your Mind."

Again, if you'd like to joins us: 800-989-8255. E-mail:

This is TALK OF THE NATION from NPR News.

CONAN: Trisha's(ph) on the line. Trisha's calling us from Charlottesville in Virginia.

TRISHA (Caller): Hi, there. I guess, you know, the question I have has to do with, you know, just what you've said there, tighten your belt. It's more of a comment. I'm from a family that has never had a problem expressing willpower. You know, we look around to people and just wonder what's the issue. You know, if you don't want to eat something, just don't eat it.

You know, and I just have always wondered why it is with people, and I'm just very curious in your research, if you have comments on that.

Dr. WANG: Do you and your family members find that you're good at not only refusing food, but other situations like social situations or...

TRISHA: Yeah, I mean, we just knuckle down and do it. If there's work to be done, we just do it, you know?

Mr. WANG: Well, that's...

TRISHA: And we don't find that this is really onerous. I'm just curious about that because in our whole family, this has been the situation.

Mr. WANG: That's interesting. There are elements of personality that heritable, and to my knowledge, people have not studied whether will power is an inherited quality, but your family might suggest that that's the case.

TRISHA: Yeah, it's absolutely expected. And we don't, you know, we're not awful people, we're not boring, we're fun. It's just what we do.

CONAN: Do you find that because you grew up in that context, where that sort of willpower was commonplace, that you have difficulty understanding why other people don't have it?

TRISHA: Yeah. And we - you know, we certainly aren't judgmental about it. I'm just - I've often been curious.

CONAN: Hmm. Well, maybe some ancestor really, really pumped up that willpower muscle.

TRISHA: Oh, yes. It's just the whole Irish thing, you know, you had to get through the salmon and everything and, you know, have fun later in the pub, right?

CONAN: That's, I guess, the idea. Trisha, thanks very much for the call.

TRISHA: Thank you. Bye.

CONAN: Bye-bye.

And let's try now, Mary(ph). And Mary is with us from Denver, Colorado.

MARY (Caller): Hi.

CONAN: Hi, Mary.

Mr. WANG: Hi, Mary.

MARY: I am on a very strict diet, having to do with allergies that I may have developed. And I've noticed - I'm a psychotherapist - and I've noticed that I am a little crankier, less patient with not only my family and friends, but also my clients. And I'd attributed it to not having any of the kinds of foods I'm used to eating. But it is now occurring to me that it may have something to do with this research that you've done, that I'm putting all of my energy into this diet, and I don't have a lot of reserves to exercise patience when I usually have been able to do that.

Mr. WANG: That's interesting. So, the studies from the Baumeister people and the studies that we describe in "Welcome To Your Brain" go into the idea that blood sugar may be a limiting resource. And one possibility, if you're on a strict diet, as you could consider things that are within your diet that allow you to keep and even keel on your blood sugar like complex carbohydrates or proteins, things that will keep you from fluctuating too much during the day. Have you thought about that?

MARY: I'm definitely doing that. I'm - doing this with an (unintelligible), and definitely focusing on all the complex carbohydrates and certain amounts of protein. I'm not doing any red meat, but certainly fish and chicken...


MARY: But I've cut back on all the caffeine, sugar, dairy, wheat, gluten - all of that is gone...

Mr. WANG: I'm feeling a little cranky just listening to this.

(Soundbite of laughter)

CONAN: I was also going to even suggest, Mary, have you considered the idea that maybe your family and your clients are all idiots, and that was just - you're just blind to it when you are eating?

(Soundbite of laughter)

MARY: I love that. Well, no, I'd rather not think that. But I definitely have noticed a shift, and more so with family and friends. But it's definitely making its way in to the client territory. But I was fascinated by your comments and your research today. It made think about it in a different way.

Mr. WANG: Given to other small impulses that are harmless, try that out and see if it helps.

MARY: Okay. I will do that.

CONAN: Okay, good luck, Mary. Thanks.

Mr. WANG: Bye, Mary.

CONAN: Here's an e-mail from Adam(ph): I'm a medical student. I just finished taking my first of a series of licensing exams. The one thing I told myself I would not do during a months I spent studying for the standardized test was to stop exercising, stop eating healthily, and start pounding the junk food.

I tried very hard, and studying always seemed to edge everything else out in my mind. I did amazingly on the exam, but I gained 12 pounds and that being and very out of shape.

Mr. WANG: Common, common experience. Everything goes, the diet goes, laundry goes - I know where Adam's been.

CONAN: Or in fact, you've probably been there.

Mr. WANG: Yes I have. In my line of work, there's - there are a lot of deadlines that come up, and we usually do it at the last minute. So I am totally sympathetic to Adam.

CONAN: And I wonder, how do you know when will power has succeeded? Was there, you know, flag to be posted on the top of that mountain of willpower?

Mr. WANG: Well, one thing that you can do is you can undertake a, say, a small task that is difficult but attainable and that it's, in some sense, sort of a will power exercise. And so if you set yourself clear goals and if you - don't set yourself too many goals at once, then that accomplishment you feel will provide reinforcement that makes you more likely to exert willpower again.

CONAN: Sam Wang, thanks very much for your time today. Appreciate it.

Mr. WANG: My pleasure. Thanks a lot.

CONAN: Sam Wang, associate professor of molecular biology and neuroscience at Princeton University, co-author of a New York Times op-ed titled "Tighten Your Belt, Strengthen Your Mind," with us today from the studios at Princeton.

Tomorrow, we'll be broadcasting live from the Newseum, all about confidential sources. Stay with us.

I'm Neal Conan. This is TALK OF THE NATION from NPR News.

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