A study of men in one Scottish city has uncovered the secret of looking irresistible to women - and it's not sexy eyes or a strong jaw line. The key is to appear desirable.

A man's face becomes more attractive when other women are seen admiring him, according to psychologists at Aberdeen University's Face Research Lab who based their studies in the city.

In the past, facial attraction was usually considered to be a matter of personal taste, with people preferring different "types" of faces.

But Dr Ben Jones found that a woman's opinion of a man's face was strongly influenced by the behaviour of other women towards him.

In the experiment, women were shown pictures of pairs of guys and asked to choose which one they found more attractive. They then watched the same guys being smiled at by another woman, or being looked at in a neutral, almost bored way.

"We found that seeing another woman smiling at a guy was enough to increase a woman's preference for that guy," said Dr Jones. "Even if they had no preference for either man at first."

Dr Jones added: "In the US, you can now hire someone to be at the bar you're going to and to flirt with you, in order to attract someone else. It's big business."

Previously, Dr Jones has shown that a woman's preference for men's faces depends on biological factors, including what stage she is at in her menstrual cycle.

When women are at their most fertile, they find more macho, masculine faces attractive, while when they are less fertile, they prefer more effeminate faces.