Day: April 20, 2007

“Ask interesting and hard questions of the data and you will find the truth,” said Dubner, author of Freakonomics.

At a lab under the supervision of veterinarians and animal psychologists in New Haven, Conn., Yale economist Keith Chen taught the capuchins how to use washers as currency in exchange for treats.

“Morality is a set of ideas (about) how each of us, individually and collectively, want the world to work,” Dubner said. “Freakonomics shows how the world really is. You can't change the world if you don't understand how it really works.”

The capuchins, known for their love of sweets, were not allowed to have money when in the general population, but only when in the testing area.

Chen tested economic theories like price shocking by varying prices of favorites like Jell-O cubes in comparison with grapes and apple slices, and found the monkeys responded similarly to humans by budgeting and making the most of their money.

He also devised two games that showed monkeys could end up feeling as if they'd won or lost, even though they'd actually broken even. Their seemingly irrational preference for the “winning” game had Chen questioning how useful the monkeys would be as a touchstone for studying human behavior. Then he found that a similar study of day traders conducted by another researcher resulted in the same psychological preference. Even when they came out even, the day traders irrationally preferred to feel they won, rather than lost money.

The best of Dubner's stories involved an incident in which one of the capuchins threw a tray of washers that ended up spilling into the general population area. The monkeys, as expected, fought for the coins and, except for one, were easily bribed with the opportunity to purchase food in order for researchers to get the washers back.

“Out of the corner of his eye, Chen saw that one monkey gave a coin to another (instead of rushing to exchange it for treats.) He thinks, am I witnessing the first instance of monkey altruism? No. He was actually witnessing something he said he really wished he hadn't seen,” said Dubner.

After a brief grooming ritual, the monkeys who exchanged the coin started to have sex. Immediately after the incident, the paid monkey went over to Chen to get food in exchange for returning the coin, Dubner said.