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The Motivation Behind What We Eat, Drink


This is MORNING EDITION, from NPR News. I'm David Greene.


And I'm Renee Montagne. The plan in New York City to ban selling large sugary drinks, Disney's new nutritional guidelines for ads it airs - those are among the latest in a long list of efforts to inspire healthier choices. And that got us thinking about the thought process, conscious and unconscious, that we experience when deciding what to eat and drink.

It's what Matt Wallaert thinks about for a living. He's a behavioral psychologist and product strategist. Good morning.

MATT WALLAERT: Good morning. Thank you for having me.

MONTAGNE: Why don't we start with why so many people are tempted by big items, big sizes. Basically, I'm asking you, are we wired for bargains?

WALLAERT: Well, wired is a really difficult term. You know, we can comfortably say maybe yes. We want, for reasons of - originally, of scarcity in the environment, right? Originally, there wasn't enough food. It was very hard to get food. So we are programmed to go get as many of those calories as we can.

MONTAGNE: And there have been plenty of studies that support this, right? This idea of a sort of bottomless soup bowl.

WALLAERT: Right. So that was a great study done by Brian Wansink and some colleagues, where they had a clever soup bowl that refilled from the bottom. And so they measured how much people would eat if they just kept refilling the soup bowl so it never really went down. And people...

MONTAGNE: And people didn't quite realize it wasn't going down.

WALLAERT: And that actually led to something we called the unit bias. Nobody eats one and a quarter apples, right? The unit is an apple. And so you eat an apple. And so you can apply that same sort of experimental logic to things like bags of chips. And you can actually make a bag of chips 20 percent bigger, and 20 percent smaller. And people still eat one bag of chips, and they eat until it's done.

MONTAGNE: So what is it about that? Like, if you can get more for less money, you'll get it - and then you'll eat it.

WALLAERT: Thriftiness has been something that's been a part of our cultural DNA since sort of the founding of the country. And you know, we see this evidence in other places. You know, there's studies that look at - in some markets, including New York, there are laws that have chain restaurants put calories on the menu. And so in restaurants like McDonald's, it seemed like they were, in fact, reducing calories.

And so when they looked at restaurants where it wasn't working, there was a bit of surprise. And one of the places it really didn't work was Subway because their main promotion - which is one of the most successful promotions ever, in advertising; the $5 footlong - you know, because the unit was a sandwich, people went, hey, it's a dollar more and I get almost twice as much food. So I'll spend a dollar more. And then when they're sitting there eating, the unit is a sandwich, so they eat the whole sandwich.

MONTAGNE: Well, there has been a fair amount of ridicule about the proposal by New York Mayor Michael Bloomberg, to ban sugary drinks over 16 ounces. Why not just let people choose for themselves? Is it because they're not really choosing for themselves?

WALLAERT: I think that's absolutely part of it. You're talking about a soda industry that spends half a trillion dollars a year on advertising. The soda industry spends that half a trillion dollars making sure that you look for bigger is better.

What potentially may happen if this ban goes through, is that you can walk into a store, and you'll see a much-larger-than-16-ounce Diet Coke, and a much-smaller-than-16-ounce regular Coke sitting next to each other. And if at an implicit level we've been quote-unquote "programmed" to look for bigger is better, it may push people towards diet soda - which ultimately, can eliminate thousands of calories from people's diet.

MONTAGNE: Tell me what the biggest challenge is, in developing food items that inspire entirely different behavior.

WALLAERT: You know, if we think of human behavior as sort of a dual process - so there are promoting pressures, reasons to do something; and inhibiting pressures, reasons not to do something - and those two are constantly at war with each other, I think that we can apply that model to looking at products, and try and increase the inhibiting pressures for unhealthy products.

One net effect of this ban may be that full-sugar soda becomes more expensive, because smaller containers generally are more expensive, on a volume to volume basis. And anybody that suggests that this won't work, if it won't work...

MONTAGNE: Well, there were a lot of New Yorkers who just came out against it - saying, the nanny mayor, that sort of thing.

WALLAERT: Absolutely, although they're reacting against a different point - which is, potentially, government intervention, as opposed to doubts about whether this will actually be effective.

MONTAGNE: Thank you very much for joining us.

WALLAERT: Renee, I appreciate it. Have a great one.

MONTAGNE: Matt Wallaert is a behavioral psychologist and product strategist. He spoke to us from our New York bureau. Transcript provided by NPR, Copyright NPR.