STEVE INSKEEP, host:
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.
(Soundbite of music)
JAD ABUMRAD: Hey, Steve.
INSKEEP: Thats Jad Abumrad of WNYC.
ROBERT KRULWICH: And this is me, Robert Krulwich.
INSKEEP: Oh, sorry, Robert, didnt mean to leave you out. Robert Krulwich as well.
INSKEEP: Okay, now, before we get started, remind us what Radio Lab is.
ABUMRAD: Radio Lab is a show where we explore big ideas that make us rethink ourselves.
KRULWICH And also the world all around us.
ABUMRAD: Right, and today were 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.
INSKEEP: Four, six, seven, one, eight, two, three, 33, nine, one, and then after that I dont know what it is.
KRULWICH: Thats good, actually, because, you know, I can do four, seven.
(Soundbite of laughter)
ABUMRAD: Robert is a special case, but it turns out theres 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: Hmm, what?
Unidentified Man #1: You want me to shut the door?
Unidentified Man #2: Yes...
ABUMRAD: Well, let me introduce you to someone.
Professor BABA SHIV (Stanford Graduate School of Business and Marketing): Im 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.
Prof. SHIV: Oh yeah, absolutely.
(Soundbite of laughter)
KRULWICH: (Unintelligible) I want to you to tell about one particular experiment that he did.
Prof. SHIV: So the experiment its pretty straightforward.
ABUMRAD: It goes like this. He got a bunch of subjects together. He said, okay, Im going to give you all a number.
Prof. SHIV: A number
ABUMRAD: on a little card, youre going to read the number, and I want you to commit that number to memory.
Prof. SHIV: Take as much time as you want to memorize the number.
ABUMRAD: Then he says
Prof. SHIV: Youre now going to walk to the next room and recall the number. And thats what subjects think. The subjects think that theyre 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.
Prof. SHIV: Thats right.
ABUMRAD: Thats all they know.
Prof. SHIV: Thats all they know.
KRULWICH: What they dont know is that not everybody is getting the same kind of number.
Prof. SHIV: Some people get a seven-digit number, some people get a two-digit number.
Prof. SHIV: That I can do by the way. I think I can do two digits.
ABUMRAD: No, I doubt it.
(Soundbite of laughter)
ABUMRAD: All the subjects have to do is theyve 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?
Prof. SHIV: Mm-hmm.
ABUMRAD: Person with a two digit number in the head is walking out of room one.
Unidentified Woman #1: One, two is my number. I can definitely remember this.
ABUMRAD: Down the hall, same time someone with seven digits in their head
Unidentified Man #3: 1228932
ABUMRAD: Walks down the hall.
Unidentified Man #3: 289
ABUMRAD: Now, heres where the trickery comes in. As theyre walking down the hall, memorizing, all of a sudden
Unidentified Woman #2: Excuse me.
Unidentified Man #4: Oh.
ABUMRAD: ...they pass the lady in the hallway, and shes holding something.
Unidentified Woman #2: Sorry to interrupt you, but would you like a snack?
Unidentified Woman #1: Um
Unidentified Man #3: Sure.
ABUMRAD: She says, here, have a snack just as our way of saying thanks for participating in the study. You can have one of two snacks. You choose
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: Meanwhile, theyve both got these numbers still in their head. Now, heres the weird thing. When they finally make their choice
Unidentified Woman #2: What would you like? Some yummy cake
Unidentified Man #1: Hmm.
Unidentified Woman #2: ...or some healthy fruit?
ABUMRAD: The people - the people, this is crazy - the people with two digits in their head
Unidentified Woman #1: You know, I love cake but I think Ill take the fruit.
ABUMRAD: Almost always choose the fruit.
Unidentified Woman #1: Its healthy.
ABUMRAD: Whereas the people with seven digits in their head almost always choose the cake.
Unidentified Man #3: You know, the cake. I want the cake.
ABUMRAD: And were talking by huge margins here.
Prof. 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 lets give them
(Soundbite of laughter)
KRULWICH: So the people with the seven digits get the cake. I get that part. I dont know why.
ABUMRAD: That doesnt interest you? As to why they would choose
KRULWICH: Well, yeah, why?
ABUMRAD: Okay, good.
(Soundbite of laughter)
ABUMRAD: Now that Ive got your interest, Ill tell you the theory.
ABUMRAD: And this is where it gets interesting. It seems that the brain is anatomically organized into different systems.
Mr. JONAH LEHRER (Science Writer): Dual systems is what theyre called.
ABUMRAD: Thats 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.
Mr. LEHRER: Theres constant competition between the rational brain and the emotional brain. Theyre always competing for attention and to guide and direct your behavior.
ABUMRAD: Especially when you have a tough choice like Baba Shivs cake versus fruit. There the competition is fierce.
Prof. SHIV: The emotional automatic system is just pushing them towards the cake.
ABUMRAD: The emotional brain loves sweet gooey chocolate cake.
Unidentified Man #4: Chocolate frosting.
ABUMRAD: Thats really what you want.
Unidentified Man #4: Give me a chocolate now.
ABUMRAD: On the other hand
Prof. SHIV: The deliberative system on the other hand comes and says wait a second.
Unidentified Man #5: Im thinking about this choice carefully.
Prof. SHIV: This probably is not good for you because
Unidentified Man #5: Calories, sugar, high fat content.
Mr. LEHRER: Think about your waistline.
Unidentified Man #5: Its going to make you chubby.
Mr. LEHRER: Think about your cholesterol.
Unidentified Man #5: It is not good for your health. It is not good for your self esteem.
Prof. SHIV: And that acts as a check.
ABUMRAD: But if you give that rational deliberative system seven numbers, just seven to memorize...
Unidentified man #5: 1228936, 12285, 122, one, a cholest 122...
ABUMRAD: Suddenly the rational brain has clearly too much to keep track of.
Unidentified Man #5: Or 2
ABUMRAD: Its getting tired.
Unidentified Man #5: 2
ABUMRAD: It cant put up as much of a fight.
Unidentified Man #5: Oh.
Prof. 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. Its how easily it wins. Seven numbers is all it takes to screw up reason.
Mr. LEHRER: Just think about how astonishingly limited that is.
KRULWICH: Yeah, I mean, compared to emotion, team reason is, well, pretty feeble.
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, Ill just set aside this cake and thank Robert and Jad for stopping in. Thank you, gentlemen.
(Soundbite of laughter)
ABUMRAD: Sure thing.
KRULWICH: We kind of knew youd do the cake.
INSKEEP: Thats Jad Abumrad and Robert Krulwich from the show Radio Lab, a production of WNYC in New York. You can explore Radio Lab at npr.org. Transcript provided by NPR, Copyright NPR.
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.
This time, you say to yourself, this time I will do 50 chin-ups every day or skip dessert or call my mother every Friday. It's time to do those things that I know, I really, really know I should do.
And then you don't.
According to British psychologist Richard Wiseman, 88 percent of all resolutions end in failure. Those are his findings from a 2007 University of Hertfordshire study of more than 3,000 people.
How come so many attempts at willpower lose both their will and their power?
In our Radiolab excerpt on Morning Edition, with my co-host, Jad Abumrad, we propose an answer ...
Jonah Lehrer, one of our regular reporters (he writes all the time about the brain), told Jad and me about an experiment involving the prefrontal cortex, located just behind the forehead. It's the brain area largely responsible for willpower. This hunk of brain tissue, he says, has greatly expanded over the last few hundred-thousand years, but "it probably hasn't expanded enough." The reason our willpower is so often weak, he suggests, is because this bit of brain lacks a certain (how shall we put this?) ... muscularity.
In his book How We Decide, and in a recent Wall Street Journal article, Jonah writes about an experiment by Stanford University professor Baba Shiv, who collected several dozen undergraduates and divided them into two groups.
In the WSJ article, Jonah writes:
"One group was given a two-digit number to remember, while the second group was given a seven-digit number. Then they were told to walk down the hall, where they were presented with two different snack options: a slice of chocolate cake or a bowl of fruit salad."
And then he writes:
"Here's where the results get weird. The students with seven digits to remember were nearly twice as likely to choose the cake as students given two digits. The reason, according to Professor Shiv, is that those extra numbers took up valuable space in the brain — they were a "cognitive load" — making it that much harder to resist a decadent dessert. In other words, willpower is so weak, and the prefrontal cortex is so overtaxed, that all it takes is five extra bits of information before the brain starts to give in to temptation."
It turns out, Jonah explains, that the part of our brain that is most reasonable, rational and do-the-right-thing is easily toppled by the pull of raw sensual appetite, the lure of sweet. Knowing something is the right thing to do takes work — brain work — and our brains aren't always up to that. The experiment, after all, tells us brains can't even hold more than seven numbers at a time. Add five extra digits, and good sense tiptoes out of your head, and in comes the cake. "This helps explain why, after a long day at the office, we're more likely to indulge in a pint of ice cream, or eat one too many slices of leftover pizza," Lehrer writes.
You can hear Shiv describe this experiment (and listen to our unique dramatization of cortexes fighting pastry) by hitting the "Listen" button up above on this page.
Radiolab is produced by WNYC in New York and distributed by NPR. Jad Abumrad and Robert Krulwich are co-hosts. Jonah Lehrer describes the Shiv experiment in much greater detail in his latest book, just out in paperback, How We Decide.
Produced by Soren Wheeler