/ 21 April 2006

Testosterone: The dither hormone

A glimpse of an alluring woman is all it takes to ruin a man’s decision-making skills and the more testosterone coursing through his veins, the worse the problem gets, researchers claimed on Wednesday.

The finding is unwelcome confirmation that those most likely to be in a position of power are most susceptible to the subtle influences of the opposite sex.

Bram van den Bergh and Siegfried Dewitte at the University of Leuven in Belgium set 44 student volunteers aged 18 to 28 a financial game to test how they reacted to fair play. The game required the students to split into pairs and before half of the games, one of each pair was shown images of a sexy woman or asked to rate how much they liked a variety of lingerie. The results showed that men exposed to what the researchers call ”sexual cues” accepted unfair play far more than men who were not.

The researchers later ranked the men according to their testosterone levels and found that the more testosterone a man had the worse he fared in the tests, they report in the journal, Proceedings of the Royal Society B.

”We all think we are rational beings, but our research suggests … that people with high testosterone levels are very vulnerable to sexual cues. If there are no cues around, they behave normally, but if they see sexual images they become impulsive,” said Dewitte. ”It’s a tendency, but these people are not powerless to fight it. Hormone levels are one thing, but we can learn to deal with it.”

Testosterone levels were gauged by measuring the ratio of the index finger to the ring finger. A low value, suggesting a ring finger longer than the index finger, is a result of high testosterone and is found more commonly in men than women.

The researchers are conducting tests to search for a similar effect in women, but have so far failed to find a visual stimulus that alters their decision-making behaviour. — Â