The Irrational Consumer: Why Economics Is Dead Wrong About How We Make Choices

A new paper reviews how psychology, biology, and neurology are ganging up on economics to prove that, when it comes to making decisions, people are anything but rational

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Daniel McFadden is an economist. But his new paper, "The New Science of Pleasure," shows the many ways economics fails to explain how we make decisions -- and what it can learn from psychology, anthropology, biology, and neurology.

The old economic theory of consumers says that "people should relish choice." And we do. Shopping can be fun, democracy is better than its alternatives, and a diverse and fully stocked grocery store ice cream freezer is quite nearly the closest thing to heaven on earth. But other fields of science tell a more complicated story. First, making a choice is physically exhausting, literally, so that somebody forced to make a number of decisions in a row is likely to get lazy and dumb. (That's one reason why stores place candy near the check-out aisle: They suspect your brain is too zonked to resist.) Second, having too many choices can make us less likely to come to a conclusion. In a famous study of the so-called "paradox of choice", psychologists Mark Lepper and Sheena Iyengar found that customers presented with six jam varieties were more likely to buy one than customers offered a choice of 24.

If you've read the work of Dan Ariely or Daniel Kahneman, you know exactly how far from perfectly rational we are when faced with a decision. Many of our mistakes stem from a central "availability bias." Our brains are computers, and we like to access recently opened files, even though many decisions require a deep body of information that might require some searching. Cheap example: We remember the first, last, and peak moments of certain experiences. So when we make a choice about how to spend a certain amount of time -- say, by going to Six Flags -- we forget that most of the time at an amusement park is spent waiting around doing nothing. Instead, we remember the thrill of the roller coaster. (This has been previously used to explain why people sometimes go back to disappointing old romantic partners, but that might be for another article.)

The third check against the theory of the rational consumer is the fact that we're social animals. We let our friends and family and tribes do our thinking for us. In a fascinating example, McFadden presents a study that shows Korean peasant women within the same village tend to use the same contraception -- even though there is "substantial, persistent diversity across villages." This pattern could not be explained by income, education, or price. Word-of-mouth explained practically all the difference.

In another corner of the ivory tower (or, more likely, across campus in a glassy lab), neurologists are finding that many of the biases behavioral economists perceive in decision-making start in our brains. "Brain studies indicate that organisms seem to be on a hedonic treadmill, quickly habituating to homeostasis," McFadden writes. In other words, perhaps our preference for the status quo isn't just figuratively our heads, but also literally sculpted by the hand of evolution inside of our brains.

A final example to show how other fields of science are ganging up on classical economics: The popular psychological theory of "hyperbolic discounting" says people don't properly evaluate rewards over time. The theory seeks to explain why many groups -- nappers, procrastinators, Congress -- take rewards now and pain later, over and over again. But neurology suggests that it hardly makes sense to speak of "the brain," in the singular, because it's two very different parts of the brain that process choices for now and later. The choice to delay gratification is mostly processed in the frontal system. But studies show that the choice to do something immediately gratifying is processed in a different system, the limbic system, which is more viscerally connected to our behavior, our "reward pathways," and our feelings of pain and pleasure.

And there's much more. To explain it, here's Daniel McFadden himself. The following transcript of our email conversation has been very lightly edited for clarity.

Let me try to sum up your paper for readers, because it covers a lot of ground. Classical economists used to posit that, since consumers are rational, we make decisions to maximize our pleasure, end of story. But your paper reviews all the ways we know that consumers aren't in fact rational but prone to all sorts of biases and habits that pull us from any strictly rational view of the consumer. Is that alright?

This is a good summary, but I think the final message is that neither the physiology of pleasure nor the methods we use to make choices are as simple or as single-minded as the classical economists thought. A lot of behavior is consistent with pursuit of self-interest, but in novel or ambiguous decision-making environments there is a good chance that our habits will fail us and inconsistencies in the way we process information will undo us.

Choices are good. Trade is good. That's the view of neoclassical consumer theory. But it turns out that people don't really like making decisions. We have habits, we like thinking automatically. So sometimes we avoid making choices altogether because it stresses us out. Why is that? And how might, say, a company use that superior understanding of consumer theory to make consumers behave a certain way?

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Derek Thompson is a senior editor at The Atlantic, where he writes about economics, labor markets, and the entertainment business.

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