Predictably Irrational: The Hidden Forces that Shape Our Decisions

A few years ago, Dan Ariely, an economist at MIT, noted something odd in the subscription rates for the British newsmagazine The Economist. You could take the first option, costing $59, and get a year of full access to their web site. The second, costing $125, would get you a year-long print subscription. And the last, also costing $125, would get you a year of both the print subscription and the online access.


The second option, it seems, is a dud. Paying $125 for the magazine or paying $125 for the magazine and the web site isn’t so much a choice as a misprint. The latter option should clearly be pricier. Odd for economists to make such an obvious error. At least it would have been, 20 or 30 years ago. But as Ariely explains in his new book, Predictably Irrational, that dud option is a feature, not a bug. The bug, rather, is in us.

For many years, economics operated off the “rational actor” model, often derided as Homo Economicus. He was quite a being, this Homo Economicus. A perfectly rational consumer, coldly calculating in his purchases, constantly pursuing his self-interest, exquisitely sensitive to the complex information being conveyed through price tags. Think Star Trek ‘s beloved Data, only with a credit card rather than a phaser.

Much of economics was dedicated to studying this rational actor’s rational actions, and rightly so. It turned out that the pursuit of self interest was a powerful motivator. But in recent years, much in economics has been dedicated to studying where the model breaks down. The emergent movement — which takes cues from psychology, sociology, anthropology, and even neuroscience — has been termed behavioral economics, and Ariely is one of its foremost practitioners.

The nice thing about traditional economics was that you could simply assume rationality. To find out how humans behave, however, requires constructing elaborate tests that allow you to watch their actions as you tweak certain variables. And that’s what Ariely excels at. His book is a compendium of these tests, both the ones he and his colleagues have designed and the ones that life has designed for them. So take The Economist‘s subscription rates. The traditional neoclassical model would suggest that if the magazine wants to offer three subscription levels, they should be priced in accordance with their value. Then we’ll get a bunch of rational consumers making rational decisions and buying rationally priced subscriptions and everyone will go home happy.

But that’s not what The Economist subscription department wants. They want to sell a whole lot of copies of their magazine. And so they need to figure out how human beings actually work. ?We don’t have an internal value meter,? writes Ariely, ?that tells us how much things are worth. Rather, we focus on the relative advantage of one thing over another, and estimate value accordingly.? Staring at those options, we know one thing: The print/web site combo is obviously the best deal. In fact, the online access seems to be?free!

To test this, Ariely gave 100 of his students at MIT The Economist‘s subscription options and asked them to choose between them. Sixteen of his students chose the internet-only option. None of his students chose the print-only option. The remaining 84 chose the combo option.

Then he asked another 100 students to choose their preferred subscription package. But he eliminated the print only option. Now they had a straight comparison between $59 for the web site and $125 for the print edition and the web site. If they were rational actors who had accurately assessed the value of the subscription options the first time, the results shouldn’t change. After all, the two plans have remained exactly the same price, and the plan that’s been removed wasn’t chosen by anyone. But when Ariely took away that dummy print rate, the choices shifted dramatically. Now, 68 students chose the online option, while 32 took the combo – a total reversal of the original preferences.

Ariely’s book goes on much in this vein. Experiment after experiment shows the delicate and unstable edifice on which our rationality rests. He relates an astonishing study in which male college students were asked to answer questions about sexual preferences, then paid money to answer those same questions while masturbating to pornography. The change in emotional state massively transformed the answers. To give two of the more unsettling answers, where 20 percent of the students originally said they would keep trying to have sex after their date said no, 45 percent of the aroused students said they’d keep pressing. And where 23 percent of the non-aroused students said they could imagine being attracted to a 12-year-old, 46 percent of the aroused students said the same. It will not shock too many in the audience to suggest that intense arousal may impede more rational thought. But the implication is significant: It suggests that “we” are not rational. Rather, we’re rational at certain times and in certain places, and only then when we’re in a certain emotional state.

Elsewhere Ariely shows how we wildly overvalue things we think of as free, relating experiments in which individuals demonstrate a preference for paying nothing in order to receive a candy of minimal value rather than paying very little for a truffle they perceived of as high value. Make the low value candy a penny, however, and that preference disappears, even though a penny may as well be free. He also shows how expectations govern experiences, and relates studies in which individuals thought the soda they were consuming tasted much better when they were told, beforehand, that it was Coke or Pepsi. And on, and on. Our decisions are based on context, comparisons, emotional states, remembered advertisements, and a whole lot more that doesn’t quite fit the description “rational.”

But Ariely’s point goes far beyond our irrationality — it is the predictability of our processing flaws that interests him. It isn’t that we sometimes make the wrong decision, but that we make it repeatedly, and in the same way, as a response to certain conditions and mental processes. Early on in the book, Ariely tells us about Gregg Rapp, a restaurant consultant who helps establishments figure out their menu pricing. ?One thing Rapp has learned,? writes Ariely, ?is that high-priced entrees on the menu boost revenues for the restaurant — even if no one buys them. Why? Because even though people generally won’t buy the most expensive dish on the menu, they will order the second most expensive dish. Thus, by creating an expensive dish, a restaurateur can lure customers into ordering the second most expensive dish (which can be cleverly engineered to deliver a high profit margin).?

The implication here is that our irrationality is not only predictable, it’s actually being predicted. Restaurants know that we anchor our frugality by deciding the priciest item on the menu is too expensive. Electronic stores know that we’re likely to go for the marked down television whose price places it in the middle of the pack. Magazines know we’ll go for whichever subscription rate looks like the best deal as compared to the other subscription rates on the page. The problem, then, is not our predictable irrationality, but the world’s asymmetric rationality. They know how we’re going to screw up, and how to take advantage of it. The only defense is being similarly aware of our flaws and failings, and trying to take into account not only how they affect our judgment, but how they’re being used against us. Ariely’s book is an excellent place to start.