Técnicas y herramientas de la Dirección de Proyectos

An important advance along that road came in 2003 with the pub- lication of a paper in the journal Science by researchers at Princeton University. In a study by Alan Sanfey and colleagues, participants in an experiment played the ultimatum game, one of the favorites of behavioral game theorists. It’s kind of like a TV game show contest in which you are given a lot of money, but you have to share your windfall with a stranger. Suppose you get $100. You then offer the stranger part of the money and keep the rest— unless the stranger refuses your offer. Then you have to give all the money back, and nobody wins anything.

In theory, the stranger should take any offer, no matter how small, in order to get something rather than nothing. Therefore, a game theorist might conclude, you should offer a low amount— $10, say, or even $1—so that you will then walk away with the most money possible. But in practice, most strangers reject low offers. If you offer $10, for instance, you’re much more likely to walk away with zero than $90, as the stranger will probably reject your offer just to punish you, even at personal expense. Conse- quently people typically share more generously—offering 40 to 50 percent of the prize, say—in anticipation of an angry rejection of an unfair offer.

So this is another case where naive game theory, in assuming that everybody will maximize their money, makes an incorrect pre- diction, as many economic experiments had already established. The Princeton study went further, though, by scanning the brains of the strangers who were considering whether to accept the offer from the other participant. In this case, the prize was only $10— science doesn’t have budgets like Who Wants to Be a Millionaire?— but the principle was the same. If the first player offered only $1 or $2, the offer was usually rejected. But not always. And you could tell who was likely to accept or reject a low offer by watch- ing what went on inside their brains.

Stronger brain activity in the front part of a brain region known as the insula (an area known to be associated with negative

emotions, such as anger and disgust) was common in players who were more likely to reject low offers. Another brain structure—the anterior cingulate cortex—also showed increased activity in those who rejected unfair offers. That region is known to be involved in monitoring conflict—in this case, the conflict between the choice of punishing a cheapskate or turning away money. “Unfair treat- ment . . . can lead people to sacrifice sometimes considerable finan- cial gain in order to punish their partner for the slight,” Sanfey and his collaborators reported in Science.10

In a commentary on that paper, Colin Camerer noted that it showed how the tenets of basic game theory do not always hold— people do not always act totally in their own self-interest (that is, maximizing their money), and all the players in a “game” therefore are not always trying to do the best they can do, as assumed in the underlying basis for a Nash equilibrium. But behavioral game theory, Camerer noted, can relax these assumptions and still learn a lot about human behavior. The neuroeconomics enterprise, in other words, is a powerful tool for developing behavioral game theory insights into how real people make choices.

Montague’s subjects at Baylor, for instance, play similar behav- ioral games that reveal the quirks of human economic behavior. In one such game—a task for testing trust—Player 1 is given $20 and is allowed to keep some of it and put the rest in a virtual pot, where the amount is then tripled. If Player 1 keeps $10 and do- nates $10, the sum in the pot becomes $30. Player 2 then gets to split the pot with Player 1—or take it all.

“If you split it 15-15, then in a sense you’ve repaid the trust,” said Montague. But if you take $29 and leave $1, Player 1 is not likely to offer much in the next round of the game. At any point in the game, one player or the other could decide to keep all the money, so the logical move is to take it all as soon as possible, before the other player does. But in fact, players typically trust each other not to be so selfish—although some are more trusting, and some more selfish, than others.

Traditional economists were not surprised at the results of such games. In the 1980s, game theory had fueled the rise of “experi-

mental economics” in which such deviations from pure self-interest showed up regularly. What’s new in neuroeconomics is eavesdrop- ping on the players’ brains via the MRI scanners while the games are in progress. Montague’s lab is particularly well equipped for this sort of thing, with a pair of scanners, one each in two rooms separated by the scientists’ observing station. The scientists watch as computers record the brain activity of players deciding how to move or how to react to another player’s move. “You can see what went on in the behavior. You can back up and look at their intent to act badly or their intent to invest more,” Montague said. “It allows us to cross-correlate what’s going on in the two brains. I think it’s cool. I think it’s an obvious way to study social interactions.”11

Neuroeconomics does not always require scanning, though. Paul Zak, director of the Center for Neuroeconomics Studies at Claremont Graduate University in California, sometimes uses blood tests instead of brain scans. He can relate variant economic behav- iors to levels of certain hormones. In one of Zak’s versions of the trust game, players communicate via computer. One player, given $10, offers some of it to another player, who is paid triple the amount offered. (So if Player 1 offers $5, Player 2 gets $15). Player 2 then can take it all, or give part of it back to Player 1. But in this version of the experiment, the game ends after just one round. There’s no incentive to earn trust so as to get more money the next time around.

So standard game theory suggests that Player 2 would take all the money, having nothing to gain by giving some back. But Player 1, anticipating that move, should therefore offer none of the money to begin with. Nevertheless, many players defy naive game theory and show at least some trust that the other player will play fair. About half of the first-movers offer some money (suggesting that they are trusting souls), while three in four of the responders give some back (suggesting that they are trustworthy).

Once again, the intriguing thing about such games is finding out what’s behind the differences in individual behavior. It turns out that among the trustworthy players, blood tests revealed higher

levels of oxytocin, a hormone linked to pleasure and happiness. Apparently the trusting gesture of the first player, by offering some money, elicits a positive hormonal response. “It tells us that people are very much responsive to their environment,” Zak told me when I visited him at Claremont. “People who got a positive signal had a nice positive happy hormone response, and their behavior reflects that.”12

Zak believes that the relationship between trust and oxytocin is central to understanding many of the world’s economic ills. Oxytocin is linked to happiness, and the countries where people report high levels of happiness are also countries where people report high degrees of trust. Trust levels, in turn, are a good indicator of a country’s economic well-being. “Trust is among the biggest things economists have ever found that are re- lated to economic growth,” Zak said.