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Intuition plays role in decision making, study shows

February 28, 1997 GMT

WASHINGTON (AP) _ In a finding that may help explain why people with damaged brains often make poor choices, researchers say playing a hunch is part of the normal decision process.

A team of behavioral scientists at the University of Iowa devised a card game to test the intuitive powers of people and found that those with normal brains can make accurate decisions based on hunch alone.

However, patients with certain types of brain damage seemed to lack this ability and in the experiment repeatedly made bad decisions, according to a study being published today in the journal Science.


The researchers, led by Antonio R. Damasio, used a card game in which the test subjects were rewarded with play money for making good choices and penalized for making poor ones.

The game consisted of four decks of cards face down on a table. Each card in the decks either gave an award or a penalty. Unknown to the players, the awards were large in decks A and B, but so were the penalties. In decks C and D, the awards were half as big, but the penalties were small. Playing decks C and D leads to an overall gain, while playing A and B produced overall losses. There was no way the subjects could predict this without playing.

Players in the experiment were 10 people with normal brains and six who have damage to the prefrontal cortex of the brain, a condition that affects the decision processes, but not basic intelligence or memory.

Researchers also measured the skin conductance response, or SCR, of each player. The SCR is a skin microsweating that is involuntary and prompted by emotion.

The game starts with the top cards in each deck producing a reward and all the players tended to pick evenly from each deck. However, by the 10th card, the heavy penalties in decks A and B started and the normal players registered anticipatory SCRs, suggesting an intuitive apprehension about those decks.

At card 20, none of the players claimed to know the differences in the decks, but the normals continued to have SCRs. By card number 50, however, the normal players said they had a ``hunch″ that decks A and B were bad choices. They registered SCRs whenever they contemplated those decks.

By card 80, seven of the normals had concluded that decks A and B were ``bad″ and would produce eventual losses, while decks C and D were ``good.″ But even the three normals who could not explain the differences in the decks still favored the ``good″ decks.


None of the brain-damaged patients ever developed anticipatory SCRs, indicating they never had the hunch that decks A and B were poor choices.

Instead, the brain-damaged patients throughout the game selected from the bad decks. This continued even though three of the patients were able to explain that decks A and B were high-risk choices.

Damasio said those three ``thought it was more exciting to play from the risky decks″ or thought that the rules would change unexpectedly.

The study, said the researchers, suggests that unconscious emotional signals can help lead normal people to make good decisions and that this ability is lacking in people with some types of brain damage.

Dr. Stephen Kosslyn of Harvard University said in Science that the Iowa study results are ``really exciting.″

``Emotion apparently is not something that necessarily clouds reasoning, but rather seems to provide an essential foundation for at least some kinds of reasoning,″ said Kosslyn.

Science is the weekly journal of the American Association for the Advancement of Science.