Romance is a puzzling thing. But scientists are doing their best to unravel the mysteries of human attachment and have now discovered that women wearing red appear more attractive to men. Men, however, are unaware that the color red turns them on.

Researchers at the University of Rochester conducted five psychological experiments to assess how color can affect how men view a woman's attractiveness. In one study, the men were shown photographs of women framed by a border of either red or white. The men tended to find the women more attractive when they appeared in the red frame. In another study, the men were shown pictures of women wearing red followed by pictures of the same women wearing another color. When wearing red, the women were more likely to score an invitation to the prom and to be treated to a more expensive date.

Red did not change the attractiveness ratings for females rating other females, the authors noted in their study, published today in the Journal of Personality and Social Psychology. And it did not change how men rated the women in the photos in terms of likability, intelligence or kindness.

The color red is linked to romance throughout nature, said the study's lead author, Andrew Elliot, a professor of psychology. Research has shown that nonhuman male primates are more attracted to females displaying red. Female baboons and chimpanzees redden when nearing ovulation to send out sexual signals.

"Our findings confirm what many women have long suspected and claimed -- that men act like animals in the sexual realm. As much as men might like to think that they respond to women in a thoughtful, sophisticated manner, it appears that at least to some degree, their preferences and predilections are, in a word, primitive," the authors said.

Other studies have shown that color can provoke a certain mood or feeling. The behavior provoked by color also depends on the situation, Elliot said. For example, seeing red in competitive situations tends to lead to a worse performance.

-- Shari Roan

Photo: Actress Mischa Barton poses in a red dress earlier this year. Credit: Michael Buckner/Getty Images.