Hunches pack decisive punches.

You gotta know when to hold 'em, know when to fold 'em-but keep in mind that an ounce of intuition trumps a pound of pondering, hands down.

That's the implication of a new study in which people tried to make money, or at least not lose their shirts, by discerning whether four decks of cards were stacked for or against them. Insightful players rapidly accumulated unconscious knowledge about the riskiness of selecting cards from each deck, based on mental updates of their picks' monetary values, neuroscientists report in the Feb. 28 Science. That information was then applied intuitively to improve their choices.

Good judgment relies on the brain's unobtrusive records of prior events in uncertain situations, from the poker table to the board room, contend Antonio R. Damasio of the University of Iowa College of Medicine in Iowa City and his coworkers. Conscious reasoning often arises as an afterthought to intuitive knowledge and the bodily reactions it evokes, such as sweaty palms or flushed skin, the scientists theorize.

They studied six patients who had suffered a kind of frontal-brain damage that spares general intelligence and memory but causes social and decision-making problems (SN: 5/21/94, p. 326). Ten people with intact brains served as controls.

Participants received a stash of phony money and four decks of cards placed facedown. They then turned over 100 cards from the tops of the decks in an attempt to find cards that netted cash rewards and to avoid cards that carried cash penalties. Picking cards mostly from two of the decks would result in an overall loss, and selecting mostly from the other two would yield an overall gain.

Questioning of the players after their first 20 selections and then after every 10 picks revealed that the controls began to favor the money-making decks well before they could articulate a strategy for choosing cards. In contrast, the six patients continued to select a large number of cards from the losing decks, even after they had figured out the most financially promising strategy.

Lowered skin resistance to a mild electric current-a bodily sign of anxiety-occurred in controls as they pondered choosing cards from the riskier decks, even before they were consciously aware of which decks to avoid.

Patients showed no such anxious undercurrents, either before or after identifying the riskier decks, possibly reflecting their inability to form or exploit an intuitive perspective on the task.