Can Marginal Utility be Measured?

Reporting in the current issue of Neuron, the scientists reveal that when a small sum of money is on the line, poorer people learn quickly how to maximize their profits, leaving their wealthier counterparts in the dust.

In a Pavlovian paradigm, a number of abstract shapes flashed in front of 14 participants. After each shape appeared for three seconds, a picture of either a 20-pence coin (roughly 40 cents) or a scrambled image followed. A card of one particular shape was always followed by the coin, and subjects were told that they could take a 20-pence piece home if they could accurately predict when the money card was the next one up....

The poorer people tended to figure out which card signaled money ahead within about 12 trials... whereas the richer people took about 35 trials.

The team next repeated the experiment while the subject's brains were scanned by an fMRI (functional magnetic resonance imaging) machine. ...This time, however, the participants did not have to physically respond. "We didn't want them to do that because there are neurons in the striatum that are responding to initiate an action of responding to reward," Tobler says. It was this response preparation that the researchers timed.

Once again, an inverse association between wealth and learning appeared, with poor people displaying more increased activity in the midbrain and striatum when compared with the more affluent subjects.

From Scientific American, the article is here.

Thanks to Rey Lehmann for the pointer.