海角大神

Does your brain freeze when offered too many options? Do you put off repainting your bathroom because you can鈥檛 bear to select among fifty shades of white (or, for the more adventurous, grey)?

If so, take heart. A famous experiment by psychologists Mark Lepper and Sheena Iyengar, published in 2000, suggests that you are not alone. In supermarket tests, they documented what鈥檚 known as the Paradox of Choice. Customers offered an array of six new jam varieties were much more likely to buy one than those offered a choice of 24.

That makes no sense in the narrow sense of rationality often used in simple economic models. More choice should always lead to more sales, since the odds are greater that a shopper will find something they want. But it didn鈥檛. On those days, in those supermarkets, with those jams, more choice meant less buying.

This result resonates with many people. I certainly behave that way occasionally. With limited time and cognitive energy, I sometimes avoid or defer choices that I don鈥檛 absolutely need to make 鈥� like buying a new jam. Making decisions is hard. Just as consumers have financial budget constraints, so too do we have decision-making budget constraints.

Today鈥檚 TED Blog provides links and, naturally, videos for a series of studies documenting similar challenges of choice, from retirement planning to health care to spaghetti sauce. All well worth a view.

But how general are these results? Perhaps not as much as we鈥檇 think from the TED talks. A few years ago, Tim Harford, the Financial Times鈥� Undercover Economist, noted聽that some subsequent studies in the jam tradition failed to find this effect:

It is hard to find much evidence that retailers are ferociously simplifying their offerings in an effort to boost sales. Starbucks boasts about its 鈥�87,000 drink combinations鈥�; supermarkets are packed with options. This suggests that 鈥渃hoice demotivates鈥� is not a universal human truth, but an effect that emerges under special circumstances.

Benjamin Scheibehenne, a psychologist at the University of Basel, was thinking along these lines when he decided (with Peter Todd and, later, Rainer Greifeneder) to design a range of experiments to figure out when choice demotivates, and when it does not.

But a curious thing happened almost immediately. They began by trying to replicate some classic experiments 鈥� such as the jam study, and a similar one with luxury chocolates. They couldn鈥檛 find any sign of the 鈥渃hoice is bad鈥� effect. Neither the original Lepper-Iyengar experiments nor the new study appears to be at fault: the results are just different and we don鈥檛 know why.

After designing 10 different experiments in which participants were asked to make a choice, and finding very little evidence that variety caused any problems, Scheibehenne and his colleagues tried to assemble all the studies, published and unpublished, of the effect.

The average of all these studies suggests that offering lots of extra choices seems to make no important difference either way. There seem to be circumstances where choice is counterproductive but, despite looking hard for them, we don鈥檛 yet know much about what they are. Overall, says Scheibehenne: 鈥淚f you did one of these studies tomorrow, the most probable result would be no effect.鈥�

In short, the Paradox of Choice is experiencing the infamous Decline Effect. As Jonah Lehrer noted in the聽New Yorker in late 2010, sometimes what seems to be scientific truth 鈥渨ears off鈥� over time. And not just in 鈥渟oft鈥� sciences like the intersection of psychology and economics, but in biology and medicine as well.

Some of that decline reflects selection pressures in research and publishing 鈥� and invitations to give TED talks. It鈥檚 easy to get a paper published if it documents a new a paradox or anomaly. Only after that claim has gained some mindshare does the marketplace then open to research showing null results of no paradox.