Women find men more attractive if they see other women admiring them
Psychologists discovered that a man was judged more desirable by a woman if she saw her peers using positive facial expressions, such as smiling.
Previous research indicated that facial attractiveness was based on personal taste and types of person.
But Aberdeen University's Face Research Laboratory found facial expressions of others could influence attractiveness.
In the study, women were shown photographs of pairs of men who were roughly matched looks-wise and asked which they preferred.
They then watched a slide show of the same men with pictures of women either smiling at them or appearing disinterested.
When asked to rate the photographs again, the majority of women developed a preference for the man who was smiled at.
Dr Ben Jones, who led the project, said: "We found that a woman smiling at a guy increased another woman's preference for him, even if she had no preference for either at first.
"It is really the first time that a phenomenon called social learning - where we learn by what other people think or do - has been shown to influence attractiveness.
"You tend to think about attractiveness being a decision of personal taste but this shows that people are influenced to a great extent by what others think of individuals as opposed to what they think about them themselves."
The research is published in the Royal Society's Biological Sciences journal.
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