AUDIE CORNISH, Host:
The first thing I thought when I saw the cover of the book "Willpower" was guilt and cupcakes. Here's why. When it comes to some parts of life, like reading books for work, I've got a lot of discipline. When it comes to other things, like defying my craving for boutique versions of desserts I can actually make at home, I've got no willpower at all.
I'm sure I'm not the only one, and I wanted to meet New York Times science writer John Tierney in person to find out why that is. And he graciously agreed to meet me at a cupcake shop in New York called Sweet Revenge, where we each picked our poison.
JOHN TIERNEY: I got the pure vanilla.
CORNISH: Yes, and I have the Crimson and cream, which is technically red velvet. So we both have our cupcakes but we're going to see who really - who reaches for the cupcake first, right, OK?
TIERNEY: All right.
CORNISH: In keeping with the spirit of the book.
(SOUNDBITE OF LAUGHTER)
CORNISH: So the title of the book is "Willpower: Rediscovering the Greatest Human Strength." Now, I thought the greatest human strength was opposable thumbs...
(SOUNDBITE OF LAUGHTER)
CORNISH: ...but it sounds like you found otherwise. I mean what - define willpower.
TIERNEY: Well, it's more than a metaphor. Willpower is more than a metaphor. The Victorians talked about this vague idea of it being some, you know, form of mental energy. And in the last 15 years, we've discovered that it really is a form of energy in the brain. It's like a muscle that can be strengthened with use, but it also gets fatigued with use.
CORNISH: Now, I was under the impression that I had different amounts of willpower for different things. That, you know, when it comes to doing things for work I had a certain amount of willpower and discipline. But when it came to other parts of my life, like exercise, my willpower seemed to be - I just didn't seem to have as much. But it sounds like you're saying that's not the case.
TIERNEY: Well, no. There is one source of energy that you draw on when you exercise self-control. And whether you're trying not to eat food, whether you're trying to do your work, whether you're trying to exercise, making decisions and resisting temptations all draws down from the same source of energy. But some things are going to affect you more than others. I mean work might be easier for you to do than exercise, simply because you enjoy it more.
So all these things are going to affect different people in different ways, but it is one source of energy. And as you go through the day you have less of it, because every time you resist a temptation, every time you make yourself do something at work, that's depleting the same source of energy. And our just sitting here with these cupcakes, by not eating them - I'm looking at that and it looks really good, and just sitting next to it is depleting my willpower.
You know, one of the tricks for dieting is to keep the food out of sight. They've done experiments in the laboratory and in real life, where just putting food where you can see it next to you depletes your willpower. Whereas putting it away in a drawer or putting it across the room, makes it easier for you because you're not actively resisting that temptation.
CORNISH: So, give us an idea how you actually test or study something like willpower. It's not just - I assume it's not just a case of putting a plate of chocolate chip cookies in front of someone and see what they do.
TIERNEY: Well, actually one of the famous experiments involves chocolate chip cookies and radishes. These students would skip a meal, go into the lab, and they'd have to wait in a waiting room. And on the table there was a plate of radishes and a plate of freshly baked chocolate chip cookies. And they found that the act of actually resisting those cookies, the people in that condition had less self-control later. They would give up sooner on tasks. They would have a harder time...
CORNISH: So the test wasn't actually the cookies and the radishes. The test was later, sort of how much...
TIERNEY: The test is later.
CORNISH: ...energy you had later on to deal with temptation.
TIERNEY: Exactly. And so, things later on you'd have a harder time doing. You could manage to get by the cookies, but then you wouldn't be able to do a puzzle. Or you'd quit sooner doing another task.
CORNISH: So what are some of the implications of this, you think?
TIERNEY: Well, one of the things is that you only have a finite amount as you go through the day, so you should be careful to conserve it.
CORNISH: Talk a little bit about, I guess, what this means then for dieters, say.
TIERNEY: Well, dieting is really the hardest form of self-control. Willpower - this store of mental energy that you have - depends on having glucose in you. And they've done to showing that you can restore somebody's willpower by giving him a drink of lemonade with sugar in it. Whereas, a drink of lemonade with Splenda doesn't do the trick, 'cause it doesn't provide the same glucose to the body.
Now, you can get glucose from lots of things and not just these cupcakes next to us. You can get it from more nutritious fare. There's this Catch-22 that dieters have, where in order to diet, you need willpower. But in order to have willpower you need to eat.
CORNISH: So you've called willpower a muscle, but how do we exercise that particular muscle?
TIERNEY: Well, there are ways that have been done. For instance, in one experiment, students were just told: For the next week, as you go about your task, sit up straight all week; is the old thing, watch your posture. And the students who did that, who worked on their posture, when they came back to the lab they would perform better on all kinds of other self-control tasks that had nothing to do with sitting up straight.
It was like basically that they'd strengthened that muscle. In almost anything you do that requires some mental effort - not using contractions when you speak, only speaking in complete sentences, saying no instead of nah, don't use profanities, saying prayers, meditating - all these things require mental effort. And the more you do that, the more it builds up that muscle.
And that's probably one of the reasons that people who are religious tend to have more self-control. This has been shown in study after study. And one of the reasons probably is that they do these exercises; most religions have prayers you say, exercises, meditations you do. All those things build up that self-control muscle.
CORNISH: What are some of the sort of hints and clues that people can look for in their own lives for when their willpower is being depleted? I mean, beyond the obvious, beyond reaching for the cupcake or the cigarette or whatever it is, what are the little red flags that you should look for?
TIERNEY: That's a great question. Scientists went through dozens of experiments trying to find what are the symptoms of ego depletion, of not having willpower? And it isn't one single thing. It's basically is that everything feels more intensely to you - good things and bad things. You suddenly feel everything more intensely because your brain has lost some of the ability to regulate emotions.
And so you therefore respond more strongly to everything. And you want, you know, cravings feel stronger, your irritation feels stronger at things. And so when you feel this, it's a sign that you're being depleted. And either try to get some glucose in you, don't make any life-changing decisions then...
(SOUNDBITE OF LAUGHTER)
CORNISH: Don't make any life-changing decisions between like two and five, I guess...
TIERNEY: Right. Late in the afternoon is good. You know, just at the end of the day, I mean, you know, people don't get into real trouble with, you know, having affairs and going out on drunken - that tends to happen in the evening.
CORNISH: John Tierney is a science writer for The New York Times. He co-authored the book "Willpower: Rediscovering the Greatest Human Strength," with scientist Roy Baumeister.
John Tierney, thank you so much for talking with us.
TIERNEY: Thank you.
CORNISH: And I think it's time to dig in, actually.
TIERNEY: All right. Well, we are replenishing our willpower now with glucose, you know.
(SOUNDBITE OF LAUGHTER)
CORNISH: This is a little bit too much glucose, I would think. But now I have an excuse for that afternoon cookie.
TIERNEY: Oh, really good. That vanilla is just amazing. Aww, now I can feel it coming back.
CORNISH: Oh, my God.
TIERNEY: The willpower is coming back. Mmm.