Radiolab: Why Is It So Hard To Do The Right Thing? The reason for a lack of willpower may be that you're working your prefrontal cortex too hard. If you give it too many jobs to do, it gets tired, calls it a day and gives into temptation.

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You know when you have a decision to make, the standard advice is to think everything through and weigh the pros and cons and reason your way to the right choice. But today we have a story about the limits of our rational minds to help us make decisions. It comes to us from our friends at Radio Lab.


JAD ABUMRAD: Hey, Steve.

INSKEEP: That's Jad Abumrad of WNYC.

ROBERT KRULWICH: And this is me, Robert Krulwich.

INSKEEP: Oh, sorry, Robert, didn't mean to leave you out. Robert Krulwich as well.


INSKEEP: Okay, now, before we get started, remind us what Radio Lab is.

ABUMRAD: KRULWICH And also the world all around us.

ABUMRAD: Right, and today we're thinking about, as you said, how we make decisions. So Steve, let me just get things started by asking you - how many numbers do you think you can remember at once?

INSKEEP: I have no idea. Test me.

ABUMRAD: All right. Ready?


ABUMRAD: Four, six, one, seven, eight, two, three, 33...

KRULWICH: This always a trick question with him.

ABUMRAD: Zero...

INSKEEP: Four, six, seven, one, eight, two, three, 33, nine, one, and then after that I don't know what it is.

KRULWICH: That's good, actually, because, you know, I can do four, seven.


ABUMRAD: Robert is a special case, but it turns out there's a classic study in psychology that asks this very question. It happened in 1956, there was a psychologist named George Miller who asked people to memorize a bunch of different stuff - numbers, letters, musical notes - and what he found is that the average human being can hold about seven items in their short-term memory, seven.

INSKEEP: Like a phone number?

ABUMRAD: Exactly. Now the interesting thing is what happens to our decision- making powers when you try and get more than seven in your head.

KRULWICH: Unidentified Man #2: Yes...

ABUMRAD: Well, let me introduce you to someone.

BABA SHIV: I'm Baba Shiv, a professor here at the Stanford Graduate School of Business and Marketing. A lot of my research has to do with the brain.

ABUMRAD: And tricking people.

SHIV: Oh yeah, absolutely.


KRULWICH: (Unintelligible) I want to you to tell about one particular experiment that he did.

SHIV: So the experiment it's pretty straightforward.

ABUMRAD: It goes like this. He got a bunch of subjects together. He said, okay, I'm going to give you all a number.

SHIV: A number...

ABUMRAD: ...on a little card, you're going to read the number, and I want you to commit that number to memory.

SHIV: Take as much time as you want to memorize the number.

ABUMRAD: Then he says...

SHIV: You're now going to walk to the next room and recall the number. And that's what subjects think. The subjects think that they're going to be doing in that study.

ABUMRAD: They know that they are going to be in one place getting a number, going to another place, reciting that number.

SHIV: That's right.

ABUMRAD: That's all they know.

SHIV: That's all they know.

KRULWICH: What they don't know is that not everybody is getting the same kind of number.

SHIV: Some people get a seven-digit number, some people get a two-digit number.

SHIV: That I can do by the way. I think I can do two digits.

ABUMRAD: No, I doubt it.


ABUMRAD: All the subjects have to do is they've got to memorize the number, walk out of room one down the hall, room two, then recite their number. Now, just imagine. You with me?

SHIV: Mm-hmm.

ABUMRAD: Person with a two digit number in the head is walking out of room one.

INSKEEP: One, two is my number. I can definitely remember this.

ABUMRAD: Unidentified Man #3: 1228932...

ABUMRAD: Unidentified Man #3: 289...

ABUMRAD: Unidentified Man #4: Oh.

ABUMRAD: Unidentified Man #3: Sure.

ABUMRAD: Unidentified Woman #2: You can choose between either A) a big fat slice of chocolate cake, or B) a nice bowl of fruit salad.

ABUMRAD: Unidentified Woman #2: ...or some healthy fruit?

ABUMRAD: The people - the people, this is crazy - the people with two digits in their head...

INSKEEP: You know, I love cake but I think I'll take the fruit.

ABUMRAD: Unidentified Woman #1: It's healthy.

ABUMRAD: Whereas the people with seven digits in their head almost always choose the cake.

INSKEEP: You know, the cake. I want the cake.

ABUMRAD: And we're talking by huge margins here.

SHIV: It was significant. I mean, this was like in some cases, 20, 25, 30 point difference.

KRULWICH: So what does...

ABUMRAD: Meaning if you have seven digits in your head you are twice as likely to choose cake than fruit, twice.

KRULWICH: So let's give them...


KRULWICH: So the people with the seven digits get the cake. I get that part. I don't know why.

ABUMRAD: That doesn't interest you? As to why they would choose...

KRULWICH: Well, yeah, why?

ABUMRAD: Okay, good.


ABUMRAD: Now that I've got your interest, I'll tell you the theory.


ABUMRAD: And this is where it gets interesting. It seems that the brain is anatomically organized into different systems.

JONAH LEHRER: Dual systems is what they're called.

ABUMRAD: That's Jonah Lehrer, science writer, who we often call when talking about brainy stuff. According to Jonah, you have a rational deliberative system which is sort of more to the front of the brain, and then deeper in the brain you have an emotional unconscious system. According to Jonah, these two systems are often at war.

LEHRER: There's constant competition between the rational brain and the emotional brain. They're always competing for attention and to guide and direct your behavior.

ABUMRAD: Especially when you have a tough choice like Baba Shiv's cake versus fruit. There the competition is fierce.

SHIV: The emotional automatic system is just pushing them towards the cake.

ABUMRAD: Unidentified Man #4: Chocolate frosting.

ABUMRAD: Unidentified Man #4: Give me a chocolate now.

ABUMRAD: On the other hand...

SHIV: Unidentified Man #5: I'm thinking about this choice carefully.

SHIV: Unidentified Man #5: Calories, sugar, high fat content.

LEHRER: Unidentified Man #5: It's going to make you chubby.

LEHRER: Unidentified Man #5: It is not good for your health. It is not good for your self esteem.

SHIV: And that acts as a check.

ABUMRAD: Unidentified man #5: 1228936, 12285, 122, one, a cholest - 122...

ABUMRAD: Unidentified Man #5: Or 2...

ABUMRAD: Unidentified Man #5: 2...

ABUMRAD: Unidentified Man #5: Oh.

SHIV: Which means greater likelihood that the emotions will drive their choices.

ABUMRAD: The astounding thing here, says Jonah, is not simply that, you know, sometimes emotion wins over reason. It's how easily it wins. Seven numbers is all it takes to screw up reason.

LEHRER: Just think about how astonishingly limited that is.

KRULWICH: Mr. LEHRER And what we always rely on it, all the advice on decision making is stop and think, slow down, take your time, and yet when you actually look at the brain, that can lead you to rely on a feeble piece of machinery.

INSKEEP: Oh, okay, well, I'll just set aside this cake and thank Robert and Jad for stopping in. Thank you, gentlemen.


ABUMRAD: Sure thing.

KRULWICH: We kind of knew you'd do the cake.

INSKEEP: That's Jad Abumrad and Robert Krulwich from the show Radio Lab, a production of WNYC in New York. You can explore Radio Lab at

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