Homo Economicus felled by contextual advertising

Emotion rules our decision-making, and even may dominate it, say researchers from the University College of London. In a behaviroal test using game theory and set-up in a gambling senario, test subjects repeatedly alterted their decisions on the same choice when presented with positive/negative context clues. The researchers looked at consistency of decision here, which is something economists assume a rational actor would retain when the decision doesn't change.

Of course, everyone has known for years/millenia that humans are irrational to a degree. In fact, the London scientists say, emotional memories may be the short-hand for the brain's learning. Persons (not in the study) whose emotional brain regions are nonactive are often unable to make decisions.

The brain images revealed the amygdala, a neural region that processes strong negative emotions such as fear, fired up vigorously in response to each two-second (on average) gambling decision. Where people resisted the framing effect, a brain region connected to positive emotions such as empathy, and another that activates whenever people face choices, lit up as well, seeming to duke it out over the decision.

"We found everyone showed emotional biases, more or less; no one was totally free of them," De Martino says. Even among the four participants who were aware they were inconsistent in decision-making, "they said, 'I know, I just couldn't help myself,' " he says.

The study comes amid a burst of research into neuroeconomics, which studies the brain's role in buying and selling decisions. Economists have embraced the idea in recent years that irrational psychology, rather than cool calculation, plays a role in such decisions. The brain study goes further and suggests that emotions rule decisions almost completely.

"The study is a very nice application of recent knowledge we've acquired about healthy cognition and emotion," says neuroscientist Antonio Damasio of the University of Southern California in Los Angeles, who was not part of the study.

"As a neuroethicist, I'd urge caution about over-interpreting this elegant study," says Judy Illes of the Center for Biomedical Ethics at Stanford University. In real life, decision-making is "an extremely complex behavior with both rational and irrational components," she says, and it is hard to capture completely in a lab setting.

Still, Illes calls the study intriguing and predicts it will lead to more work in the neuroeconomics arena.