EVER wondered why con artists find it so easy to hoodwink the elderly? Researchers in Iowa have discovered that many older people have localised brain damage that impairs their ability to avoid risky decisions.
Daniel Tranel, Natalie Denburg and their colleagues at the University of Iowa in Iowa City were studying a group of elderly patients with known damage to the ventromedial prefrontal cortex, a part of the brain that deals with decision making. In a test gambling game with cards, these patients keep losing, despite increasingly clear signs that the choices they make are bad.
But the team had a surprise when they looked for healthy controls for their tests. It turned out that about a third of their controls of the same age performed just as badly on the gambling task as the brain-damaged people in the study.
To investigate further the team recruited 40 people aged between 56 and 85, and 40 younger people aged between 26 and 55. Each group had a similar spread of educational backgrounds and all the volunteers performed normally in tests of memory, perception, language and reading.
They then tested the volunteers on a gambling game. Each was given $2000 and four decks of cards. The object of the game was to win money by drawing cards from any deck. All the decks had cards that carried rewards, but two decks also contained cards that carried severe penalties.
After being stung by the bad decks a few times, the younger people learnt to avoid drawing cards from them, says Tranel. But 14 of the older people kept playing the bad decks, and 11 others were slower than average to cotton on. "They don't develop risk aversion," says Tranel.
The researchers think some older people may suffer age-related damage to the ventromedial prefrontal cortex, and that the damage goes undetected because they are otherwise completely healthy. This may help to explain why old people so often fall victim to fraudulent advertising. A1996 survey showed most victims of fraudulent telephone marketing are 50 or older.
Author: Alison Motluk
New Scientist issue 6th November 99
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