Mind Reading explores the burgeoning field of neuroeconomics:
The fMRI [functional MRI] machine enables researchers in the emerging field of neuroeconomics to investigate the interplay of fear, anger, greed and altruism that are activated each time we touch that most intimate of our possessions, our wallets.
A neuroeconomic experiment begins with a typical behavioral-economics experiment — just add fMRI:
Economists have many ways of demonstrating the irrationality of their favorite experimental animal, Homo sapiens. One is the “ultimatum game,” which involves two subjects — researchers generally recruit undergraduates, but if you’re doing this at home, feel free to use your own kids. Subject A gets 10 dollar bills. He can choose to give any number of them to subject B, who can accept or reject the offer. If she accepts, they split the money as A proposed; if she rejects A’s offer, both get nothing. As predicted by the theories of mathematician John Nash (subject of the movie “A Beautiful Mind”), A makes the most money by offering one dollar to B, keeping nine for himself, and B should accept it, because one dollar is better than none.But if you ignore the equations and focus on how people actually behave, you see something different, says Jonathan D. Cohen, director of the Center for the Study of Brain, Mind and Behavior at Princeton. People playing B who receive only one or two dollars overwhelmingly reject the offer. Economists have no better explanation than simple spite over feeling shortchanged. This becomes clear when people play the same game against a computer. They tend to accept whatever they’re offered, because why feel insulted by a machine? By the same token, most normal people playing A offer something close to an even split, averaging about $4. The only category of people who consistently play as game theory dictates, offering the minimum possible amount, are those who don’t take into account the feelings of the other player. They are autistics.
Here’s where the fMRI comes in:
The fMRI machine shows how all this works inside the brain. A low offer stimulates activity in the brain’s insular cortex, a relatively primitive region associated with negative emotions including anger and disgust. This appears to compete with the more highly evolved prefrontal cortex, the locus of the rational impulse to take the dollar and go buy a soda with it. The more activity in the insular cortex, the more likely subjects were to reject the offer.
Some more findings — including some gender differences:
The cingulate cortex, which processes both emotions and abstract thinking, becomes especially active after one player betrays the other by cutting back on how much he shares — as if the brain, or at least this crucial part of it, is “hypertuned” to detect betrayal. Quartz has also seen intriguing differences between men and women in the scanner. Men’s brains tend to shut down after they’ve made their decision, awaiting a reply from the other subject. But women don’t relax so easily; they show continued activity in at least three areas — the ventral striatum (the brain’s center for anticipating rewards), the ventral medial prefrontal cortex (which is involved with planning and organizing) and the caudate nucleus (a checking and monitoring region, sometimes associated with obsessive-compulsive disorder). Women, says Quartz, seem to obsess more over whether they did the right thing — and how the other subject will react to them.There’s one other intriguing discovery coming out of this work, which has even the scientists baffled: with approximately 85 percent accuracy, the subjects, separated by the distance from Los Angeles to Texas, can guess whether they’re playing against a man or a woman. They appear to be picking up on subtle clues in the interactions that the scientists themselves haven’t identified.
(Hat tip to Marginal Revolution.)