October 28 (HealthDay News) -- Red really is the color of love for men, according to two University of Rochester psychologists who conducted a series of experiments to determine how color affected men's responses to women.

The results showed that red makes men feel more amorous toward women, even though males aren't aware of the impact red has on their feelings.

Red has long been linked to romantic love and passion, but this is the first scientific evidence of its effect on relationship behavior. The findings were published online Oct. 28 in the Journal of Personality and Social Psychology.

"It's only recently that psychologists and researchers in other disciplines have been looking closely and systematically at the relationship between color and behavior. Much is known about color physics and color physiology, but very little is known about color psychology," study co-author and psychology professor Andrew Elliott said in a university news release. "It's fascinating to find that something as ubiquitous as color can be having an effect on our behavior without our awareness."

Elliott and Daniela Niesta, a postdoctoral researcher, studied men's responses to photographs of women under a variety of color presentations. The men were asked to look at photos of women framed by either red or white and asked a series of questions, such as "How pretty do you think this person is?" This was repeated in other tests that compared red with gray, green or blue.

In another experiment, the shirts of women in photos were digitally colored red or blue, and the men were asked about their attraction to the women and their intentions regarding dating, including how much money they would spend on their date.

Compared to when they were shown pictures with other colors, the women were considered by the men to be much more attractive, sexually desirable, and worthy of a more expensive date when they were framed by or shown wearing red. But red didn't affect how men rated the women in terms of likeability, intelligence or kindness, and had no effect on how females rated the attractiveness of the other females.

Social conditioning may partly explain red's aphrodisiacal effect in men, but their responses likely stem from deeper biological roots, said the researchers, who noted that previous studies found that nonhuman male primates are particularly attracted to females displaying red. For example, female chimpanzees and baboons redden when nearing ovulation -- a clear sexual signal to males.

"Our research demonstrates a parallel in the way that human and nonhuman male primates respond to red," the study authors concluded. "In doing so, 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 findings have implications for product design and marketing, the fashion industry, and dating, according to the researchers.

And while this study found that red enhanced men's romantic feelings, other studies have found the impact of a color can depend on context. For example, it's been shown that the presence of red in competitive settings, such as sporting events or written examinations, results in worse performance.

SOURCE: University of Rochester, news release, Oct. 28, 2008