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Impaired intuition. People who have lesions in the ventromedial prefrontal cortex often make poor choices in life.

The Brains Behind Intuition

Have a hunch? Maybe you should act on it. Scientists have found key differences in decision-making behavior between normal individuals and those with a certain form of brain damage. The provocative findings, reported in today's issue of Science,* suggest that intuition plays a crucial role in our ability to make smart decisions.

A team led by neuroscientist Antonio Damasio of the University of Iowa College of Medicine in Iowa City gave $2000 of play money and four decks of cards to each of 10 normal volunteers and six patients with damage to the ventromedial prefrontal cortex region of their brain, an area thought to be involved in emotions and decision-making. Such patients perform well on intelligence-quotient and memory tests, but often make disastrous financial and personal decisions, and commonly show little emotion.

The subjects were told to turn over cards from any deck and to try to win as much money as possible. They didn't know there were two types of decks. Most cards in the two "bad" decks gave a $100 reward, while a few cards told subjects to hand over large sums. Most cards in the two "good" decks, by contrast, carried rewards of only $50, but the penalty cards were less severe as well. In the long run, choosing cards from the bad decks results in a net loss, and choosing from the good decks gives a net gain.

The normal individuals early on began to pick more often from the good decks and showed changes in electrical patterns in the skin that accompany changes in emotion. This behavior started well before the subjects could say that picking from the good decks seemed to be a better strategy. The brain-damaged patients, on the other hand, never expressed a hunch that some decks were riskier. Even after they had figured out that the "bad" decks led to an overall loss, they continued to choose from them some of the time.

According to Damasio, the findings suggest that in normal people, nonconscious emotional cues may play a role in decision-making before conscious processes do. He believes the ventromedial prefrontal cortex is part of a system that stores information about past rewards and punishments, and triggers the nonconscious emotional responses that normal people register as intuition or a "hunch." So agrees neuroscientist Read Montague of Baylor College of Medicine in Houston. "Something has collected the statistics ... and starts nudging behavior," Montague says, "all before [the subjects] know what is happening."

* For more details, Science Online subscribers can link to the full text of the Report.