Hungry, Hungry Hippocampus

The transcript below may be for an earlier version of this episode. Our transcripts are provided by various partners and may contain errors or deviate slightly from the audio.

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SHANKAR VEDANTAM, HOST:

This is HIDDEN BRAIN. I'm Shankar Vedantam.

SARAH REZA: Hi.

VEDANTAM: Hi. How are you?

S REZA: Oh, my God. Thank you.

VEDANTAM: I'm great. It's good to see you.

Sarah and David Reza (ph) recently bought a place outside of Washington, D.C. They sound excited because this is the first time they're hosting both their families.

S REZA: We are making today a vegetable frittata with tomato, basil and goat cheese. We've got home fries. We've got regular waffles and...

VEDANTAM: Sarah and David wanted to start a new tradition - cook brunch with ingredients from their home garden.

S REZA: The home fries have rosemary from our garden, and the frittata has basil from our garden.

VEDANTAM: This is Sarah's way of going back to her family's roots. She remembers her mother doing the very same thing.

S REZA: I remember growing up, my mom had a garden. And she would always come back with, like, these tiny little tomatoes and be like, I provided for my family; look, family, I grew this. And we're like, yeah, that's the smallest tomato ever. But there's something about being able to grow stuff and being able to give it to people that you love that's pretty exciting, so yeah.

ZACH: My grandmother would always say that...

VEDANTAM: This is Sarah's brother, Zach (ph).

ZACH: ...That sharing food is important. But I'd I say the most important part is being around the table and...

S REZA: But food was the lure to get everyone to (laughter)...

ZACH: Food - yeah, exactly. Food kept us there. Yes, exactly. Food brought us together, but it was the - it's the company and the conversation.

VEDANTAM: Today on HIDDEN BRAIN - the profound role that food plays in our lives.

PAUL ROZIN: Food is not just nutrition that goes in your mouth or even pleasant sensations that go with it. It's - it connects to your whole life.

VEDANTAM: We look at the culture and psychology that determine what we eat, what we spit out and when we come back for more.

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VEDANTAM: Paul Rozin has been studying the psychology and culture of food for more than 40 years. He works at the University of Pennsylvania. Early in his career, Paul found himself pondering a question that few of us might think to ask. Why do so many people across the world enjoy the hot, stinging pain of chili peppers? This question took Paul to a small village in Mexico, where chili peppers were as common as salt and pepper in the United States.

ROZIN: They don't think their food tastes good without it. And the little kids don't like it, so something happens somewhere between 2 and 5 years of age at the meals where everybody - adult is eating the hot pepper and the older children are, and they're all enjoying it, and the little kid is thinking, it's terrible. And after a while, some magic occurs, and the little kids like it. So I thought, well, there are a number of possible accounts. Some accounts involve something fundamentally biological.

VEDANTAM: And presumably, the biological explanation would be if you start eating it long enough, you're eventually just going to like it for biological reasons.

ROZIN: Yes, that's right. The brain compensates for all sorts of things. We adapt to things. And this is a case of more than adaptation where you're turning something that's negative into something positive. I mean, to me, that's an amazing thing, that we can start with something that's innately negative and make it really positive. So I said, let's take a look at the animals in the village because the dogs and the pigs eat Mexican food. They're eating tacos and hot sauce and beans and all of that stuff. So I went around the village, and I first asked people, do you have any dogs or pigs that like hot pepper? And they said, what are you, crazy? I said, well, yeah, I mean, they eat it.

VEDANTAM: (Laughter).

ROZIN: They said, that's ridiculous. I said, would you mind if I give the dogs a little piece of cracker with some hot sauce on it and without and see what they choose? So they said, go ahead. And so I did, would go around the village with pigs and dogs. I put out one cracker in front of them with hot pepper sauce and another without. And I'd see what they did. And it turns out that none of them ate the hot pepper first. They all ate the one with hot pepper because they're hungry. But their first choice was the one without hot pepper. So I couldn't find an animal in the village that did what everyone over 5 years old and humans did, which was to gobble this stuff and prefer it. So that suggested to me that it seems to be uniquely human.

VEDANTAM: And so this is not just a question of people getting used to it and getting to like it because the dogs and pigs are eating the garbage. The garbage is laced with chili peppers. If that was the case, that would be true for the animals, as well. So what was happening in the humans, in the human brain, if you will, that allowed 5-year-old children to fall in love with chili peppers and kept their canine cousins from liking it?

ROZIN: Well, that's, indeed, exactly the question. We don't know how this happens. But we do know that where it happens at the meals where the kids are eating with their parents and their older siblings, and they keep eating it because there's social pressure to eat it. Now, the animals keep eating it too because they're hungry. So it can't be just that they keep eating it. So it's really, to me, a miracle.

And what I realized is that it's a miracle that takes place in humans all over the world, not just about hot pepper. It's also about liking coffee, which is bitter, and people don't like it originally - and they like it. And it goes outside the food domain. People like to go on roller coasters. Now, a roller coaster is a very negative experience the first time you have it, right? You think you're crashing to death.

(SCREAMING)

ROZIN: And your heart is pounding. And yet people pay to do this. Can you imagine a dog paying to go on a roller coaster?

VEDANTAM: (Laughter).

ROZIN: I mean, you know, it just won't happen. So we found that there's a whole range of things in which humans enjoy what is originally negative, and they come to enjoy it as positive. This includes the fatigue of running. It includes sad movies. It includes being afraid in horror movies. And this seems to be only humans.

So our thought - and it's only a thought - is that what humans are enjoying is the very fact that their body thinks that something is bad, but they know it's OK. We call it benign masochism. Humans have this special ability to appreciate the fact that they know that something that their body is saying is bad is actually good. And we have evidence for that. So, for example, for chili pepper, the favorite degree of hotness is just below the level of unbearable pain. They're pushing as far as they can to get their body to really scream, get this out of here and, yet, know that it's OK. So it seems to be a very general feature of humans, which we tapped into by asking why the couple of billion people like hot pepper.

VEDANTAM: So in some ways, the theory is that you start out not liking it, and then social pressure, if you will, convinces you to try it. And then you try it often enough that your body learns to adapt to it a little bit. But then eventually, you start to like it for actually a slightly different reason. You're no longer liking it just because of the peer pressure or the social interactions. You're liking it because it gives you a sense that you're coming close to the edge of something thrilling. Is that the argument?

ROZIN: Yes. It's something thrilling that is not threatening.

VEDANTAM: Right.

ROZIN: So, for example, if something is threatening, you don't get to like it. Like, people don't get to like serious pain. It has to have something of the sense of it's not really threatening. And it even becomes funny. So in the case of disgust, people don't like disgusting things, right? But they make exceptions. They eat smelly cheese. And they come to like that smell in the context of the cheese, even though their body is saying, get this out of your mouth; it stinks.

VEDANTAM: You once performed an experiment on yourself. You were with your wife, I believe, at a Korean restaurant in New York City. And you did...

ROZIN: Yeah.

VEDANTAM: ...An interview with NPR back in 2015 where you told the reporter that it was one of the hottest things you'd ever eaten. Tell me that story.

ROZIN: Well, my wife at the time was a cookbook writer, and she was very interested in cuisine. And we went to a Korean restaurant in New York. And the people around us, they were ordering some dish that we didn't recognize, so we said to the waiter, we would like that. And he says, you don't want that. I said, no, no. We said, we really like to try new foods. He says, you don't want to try that food. So this went on, and we won, of course. And he brought this dish. And it was unbearably hot, and we ate it because we were shamed into eating it by our own insistence that it was good.

I have another story of a different sort. It also happened in New York. I had a colleague who had a dog, and the dog liked to eat dog poop. So they would go into Washington Square Park and - with the dog. And the dog would just hunt out a dog poop and eat it. And it was just awful. You know, they hated it, and the dog smelled and every - so they went to a vet. And the vet said, why don't you put hot pepper on the dog poop? - because dogs don't like hot pepper. So they go into Washington Square. I want you to get this image. Barbara's (ph) holding the dog on a leash. And her husband goes with a shaker of hot pepper, finds a dog turd and seasons it in front of everybody with all this hot pepper, OK?

VEDANTAM: (Laughter).

ROZIN: And, I mean, the idea of someone seasoning a dog turd is really pretty good. And then they let the dog go, and the dog ate it.

VEDANTAM: And did the dog stop eating dog poop?

ROZIN: No, no, because the dog liked dog poop more than it disliked the hotness.

VEDANTAM: (Laughter).

ROZIN: You know, people will put up with pain to do something they really like, right?

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VEDANTAM: Just as Paul has shown that the sense of taste is shaped by the brain, he's also done work that shows the same thing for appetite. In one study, he set a meal down before patients who had amnesia.

ROZIN: The general view in most of the people who work on hunger is that hunger comes when, you know, your body reserves are low or your - maybe your blood glucose is low, various hormones come out. And you feel this sensation of hunger, and you eat until it disappears. Now, there's some truth in that, of course, but there are many other higher-order things. So, for example, the cultural definition of - what's a meal? - is very important. After you finish the meal and have dessert, you stop eating. So to try to show this, we dealt with a - two amnesic patients who are totally amnesic. They didn't remember anything that happened more than 30 seconds ago. But they were quite intact otherwise.

So we fed them lunch in a situation where they were in a room without a clock. And we said, lunchtime. And it was lunchtime, and we brought them a favorite lunch of theirs. We'd asked them what their lunch was. And they, of course, ate it. Then we took the plate away. There were no more signs that they'd eaten. And 10 minutes later, we brought another lunch and said, lunchtime. And they all ate it three times each - the second lunch, completely. Then we took that away, waited 10 minutes and brought a third lunch. Each of these were full-sized lunches. And most of the time, they ate the third lunch. Twice, I think, one of them said, I'm getting a little stuffed, meaning their stomach was really getting full. But the point was that they're eating - when you're served a meal, it's - and if it looks palatable, you tend to eat it.

I've been - I was on a plane once flying to Chicago. And at 3 in the afternoon, they served a full lunch. Now, everyone had eaten lunch already, but six out of the nine people who I could see ate that lunch because it was lunch, and it was food, and it looked good - probably wasn't good if it was airplane food. But - and they ate it. So a lot of what we do is we eat when there's good food around and when the situation is appropriate. Now, if we had left their first lunch, and they saw the plate in front of them with a - there was pieces of chicken bone - they might've realized that I've just eaten. And when we give people - normal people - a second meal in the same way I just described, they don't say, I'm not hungry. They say, I just ate.

VEDANTAM: So it's fascinating because I think what you're saying really is that memory plays a huge role in whether we think we're hungry.

ROZIN: Yes. Being hungry is only one reason that we eat. So if you go for a full dinner, halfway through that dinner, you're not hungry anymore. But you're still eating the rest of the meal.

VEDANTAM: That's right.

ROZIN: So hunger can institute meals. The lack of it will probably discourage you from eating more. But there are other things that influence you, too.

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VEDANTAM: When we come back, one of those things is the role that culture plays in our experience of food. We'll also look at how you can serve more memorable meals. Stay with us.

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UNIDENTIFIED SINGER: (Singing in Arabic).

VEDANTAM: Some time ago, one of our producers attended a dinner for Ramadan, an iftar, at an apartment in Washington, D.C.

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VEDANTAM: Ramadan is the ninth month of the Islamic calendar and commemorates the first revelation of the Quran to the Prophet Muhammad. Food plays an important role during Ramadan. For 30 days, Muslims like Asmaa Albaroudi (ph) fast from sunrise to sunset as a way to practice self-discipline and to reflect on their connection to their faith.

ASMAA ALBAROUDI: So not being able to eat all day and then coming and having that meal makes you grateful for what you have.

VEDANTAM: By deliberately going without food, Tesneem Alkiek (ph) says hunger can make people mindful about the role that food plays in their lives.

TESNEEM ALKIEK: The prophet - he's kind of - he narrated, saying that you should fill your stomach with three things - one-third for food, one-third for drink and one-third for air. And so I'm always thinking about that, especially after a long day of fasting because it's a natural instinct to just put three-thirds full of food. And I'm keeping that in mind. And I'll - constantly reminding myself to always leave room to properly breathe.

VEDANTAM: Breaking the fast comes with its own rituals.

ALKIEK: So it's a really, I think, a communal experience. You break your fast almost every single night with friends and family, and you go to the mosque afterwards.

VEDANTAM: Many Muslims at iftar dinners aren't just breaking a fast. They're enacting and reinforcing their sense of identity. Ramadan illustrates the profound role that food plays in shaping our cultural behavior and how culture, in turn, can shape the way we think of food. And that's the case for Ahmad Asaad (ph).

AHMAD ASAAD: Food is just, like, the glue that holds a lot of cultures together. You know, when I'm - like, I'm looking around the room right now, and there are people from probably, like, seven or eight different countries. So it's one of those things just, like, you appreciate other cultures. And you appreciate, I think, the oneness of, you know, what we are and what Ramadan stands for as a whole.

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VEDANTAM: Psychologist Paul Rozin has spent many decades examining the interplay between food, identity and culture.

ROZIN: Food is not just nutrition that goes in your mouth or even pleasant sensations that go with it. It connects to your whole life. And it's really a very important part of performing your culture and experiencing your culture.

VEDANTAM: When Paul asked people about their favorite meals, they certainly mentioned eating at great restaurants, but they also talk about meals with friends and family, like the one we just heard about.

ROZIN: Here's a very common answer that's very short for a home meal. Every Christmas Eve, my Italian grandfather and Greek grandmother would cook a meal consisting of creamy carbonara with bacon pieces throughout, homemade spinach pie and sausage. It was always amazing. Now, that's a lovely one, right? And it's not fancy, but you can see the emotion and the pleasure of it.

VEDANTAM: And it's connected, of course, to the pleasure of family, not just to the pleasure of food.

ROZIN: Yes. It's very social. Another one - the best meal I have ever had in my life was when I got out of jail. Having been in jail for three years and eating prison food was horrible. When I got out, I got a Hardee's Frisco burger combo meal. That was the best burger and fries I have ever had. OK, so that's - you know, it's a context. It's a release from bad eating. So the contrast is so important there.

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VEDANTAM: Contrast and context can also be important when it comes to thinking about an individual meal. Consider the difference between a tapas-style meal and a meal that's built around one large entree. In both cases, you can fill up your stomach. But it turns out, these have very different effects on your brain. As social scientists have found, most of us find it difficult to tell the difference between the 10th bite and the 11th bite of the very same food.

ROZIN: There's a whole line of modern decision research - mostly associated with Daniel Kahneman, who got a Nobel Prize for it, and Amos Tversky - showing that, you know, people are not so rational as you might expect them to be. And one of the features of it is called duration neglect, which is people don't remember how long an experience is; they just remember the experience. So if you had pain for 12 hours or pain for one hour, two weeks later, what you remember is the experience of the pain, not how long it was. So this, applied to food, means that if you've had the same food - a lot of the same food - it won't produce a very different memory from having a little of that same food because it's the memory of eating the food.

So this raises a very important question that Kahneman originally brought up, which is, the distinction between your experience and your memory for the experience. Kahneman and others have shown - we've done some work on this, too - that the ending of an experience is particularly important. So when you remember something, you're more likely to remember the end of it and also, by the way, to some extent, more likely to remember the beginning of it. And that would mean if you want to produce the best memory for food, you should put the best foods at the beginning and the end, whereas most people think the entree is the best, which is in the middle and is the least-remembered.

VEDANTAM: We had Danny Kahneman on HIDDEN BRAIN recently. And, of course, he talked about the peak-end rule and also about the difference between the experiencing self and the remembering self.

ROZIN: Yes.

VEDANTAM: And one of the implications of this, as you point out - this difference between experiencing a meal and remembering a meal - is it points to the difference between people who go to restaurants and order their favorite dish every time and people who go to a...

ROZIN: Yeah.

VEDANTAM: ...Restaurant and order a new dish every time. How are these two strategies essentially catering to two different psychological impulses?

ROZIN: Well, that's an issue that we have looked at, and it's pretty clear. If you're going to order your favorite food, and you know you're going to order that before you go to the restaurant - there are actually three aspects. There's your anticipation - this comes from Kahneman - the anticipation, the experience and the memory. Your anticipation of a meal is going to be higher if you order your favorite food because you know you're going to have something great - right? - whereas if you can order something new, it's not even clear what you can imagine because you don't know what it is.

At the meal itself, you're probably going to enjoy your favorite dish more than a new dish because it's one of their best dishes. You love it. There's a little risk in ordering something new. But if you order your favorite dish, you're not going to create a new memory, whereas if you order a new food, you're going to create a new memory. We are looking at this - but we don't know yet for sure - if you're a person who generally values memories, then you're going to try to create more memories by creating new experiences, whereas if you value anticipation and experience more, you will keep doing the same wonderful thing.

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ROZIN: So how you value anticipation, memory and experience affects how you're going to choose what activities you do. Let's just take an example - massage, OK? I like massage. I go once a month. I get a massage. It's pretty much the same. I can't tell you last month's massage was exactly this. So I'm going for the anticipation and the experience, which is very positive. I don't really create much memory from this. And I do it, and I like it, but it's very different from the way I eat, where I'm always trying to say, I want to enrich my mental menu list thing - you know, my life experience of food. But people differ on this. We've been interested in trying to see if people can - are consistently different. We don't know yet.

Think of a seven-day Caribbean vacation at a resort. Almost nothing happens, right? You're feeling good. The sun is good. You go in the water. It's nice. But there's no - if people say, tell me about your vacation, it's going to be a very short thing, right? So there's two kinds of vacations - those that are really high on experience and vacations that will give you a lot of experience, but there'll also be some hardship. You'll get tired. Something may not work. Something might be closed when you thought it was open. All kinds of things can happen. So it won't be a totally positive experience, but it will be a bunch of good memories.

VEDANTAM: You've thought a lot about the differences between the American attitude toward food and the French attitude toward food. And you say that the French are more focused on what happens in the mouth, and Americans are often more focused by what happens in the bloodstream. I want to play you a short movie clip that illustrates this idea.

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JULIE GONZALO: (As Shelby) Well, if it isn't diner girl.

(LAUGHTER)

HILARY DUFF: (As Sam Montgomery) What can I get you guys?

GONZALO: (As Shelby) What can I get here that has no sugar, no carbs and is fat-free?

DUFF: (As Sam Montgomery) Water.

UNIDENTIFIED ACTOR: (As character) Water? Feisty.

VEDANTAM: So that was from the movie "A Cinderella Story," Paul. And I'm wondering if you can just talk a little bit about this - the American attitude toward food versus the French attitude toward food.

ROZIN: I go to France a fair amount, and they seemed to be enjoying their food more than we were. And interestingly enough, they're marginally healthier than we are. I mean, it's not a big difference, but they live a little longer, and they have less heart disease. And yet they eat a diet that's higher in animal fat than we do. It's OK if we're worrying about food. And the consequence of that is that we're going to live longer. But we seem to be worrying about food and not living longer, so that seems like a bad exchange.

So we started a study of how French and Americans differ in the way they eat. And it's basic. You got two parts to it. One is how they think about food, and the other is how their food world is set up. The French think about food as an oral experience. They think about eating as something that is giving them pleasure. They don't tend to think about what's going into their bloodstream, how much sugar is in there, animal fat. So they're getting more pleasure out of food because they're not worrying about it.

So for example, if we ask French, when you think of heavy cream, do you think of whipped or unhealthy? They will say, usually, whipped. And Americans will say unhealthy. Now, it's the same thing, but they're thinking about it as an experience, and we're thinking about it more as a health event.

VEDANTAM: And in some ways, that actually might be a good thing - right? - because presumably, when you take more pleasure in food, you're focused on it. You're not necessarily just focused on getting stuff in your mouth or focusing on nutrition. The French, for example, seem to pay more attention to portion control than Americans, except that I don't know if they're thinking about this as control. They're thinking about this as the enjoyment of food, and once I'm done enjoying this bite, I'm done with it.

ROZIN: Well, they eat more slowly, first of all. So they have more mouth experience because they don't swallow as quickly. They savor the food. So, I mean, if you have a chocolate bar, you can, you know, bolt it down in a couple of minutes or you can make a 10- or 15-minute experience out of it. And they're more inclined to the latter. We actually were able to measure how - in McDonald's, in Paris, how long people sat and ate compared to McDonald's in the United States, OK? And we made sure they were French people in the McDonald's. They were talking French. The French people sitting in McDonald's sit there for longer than the American people sitting in McDonald's. So they're eating more slowly. They're talking more. You know, they're not just bolting down food. Food is not fuel.

Americans often - not always - treat food as fuel, whereas the French think about it not as a fueling but as an event and experience. Now, in the food world, the big difference between the French and Americans is portion size. French traditionally serve smaller portions. If you look at a French cookbook, the amount of meat for four people per person is less than an American cookbook. In McDonald's in France, the portions are smaller. Now, if you remember our discussion of the fact that you eat what's in front of you if it's pleasant - the amnesic patients - the French put less food in front of you, and so they're eating less and enjoying it more. And that seems to me to be a good formula.

Now, they have other features of it. The French meal is a much more elaborate event. People don't get up - especially at home - they don't get up in the middle of the meal and just leave the table. Everybody eats the same thing. So it's a social event. So I would say the French deal with food well in the face of the modern world where there's so much good food around them. We could easily stuff ourselves and eat everything under the sun. They are - they have managed to have a tradition which keeps it moderate and very pleasant.

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VEDANTAM: Paul Rozin has been studying the psychology and culture of food for over 40 years. He's currently at the University of Pennsylvania. Paul, thank you for joining me today on HIDDEN BRAIN.

ROZIN: It's been a pleasure.

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VEDANTAM: This episode was produced by Thomas Lu and edited by Tara Boyle. Our team includes Jenny Schmidt, Parth Shah, Rhaina Cohen and Laura Kwerel. Armies are set to march on their stomachs. So, too, it turns out, are podcast teams. Our unsung heroes this week are Marco Martire, Janis McLean and Jeff Deweys (ph) at NPR's cafeteria, Sound Bites. On days you hear a pep in my voice, it's probably because of one of Jeff's omelets. Thank you Marco, Janice and Jeff and all of your colleagues.

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VEDANTAM: I'm Shankar Vedantam. And this is NPR. Transcript provided by NPR, Copyright NPR.