Wearing red could give an advantage in the dating stakes, say the experts
Women who don a little red dress before going out with a man may find their date more attentive and generous, according to scientists.
The University of Rochester study, published in a psychology journal, supports other evidence linking the colour to attractiveness.
Men said they would spend more money on a woman pictured in red, compared with the same woman wearing a blue shirt.
Experts say that red signals ovulation or attractiveness in other species.
The colour has traditionally been linked with romantic and sexual matters, from red hearts on Valentine's Day, to red-light districts.
The researchers say that their study is clear evidence that the colour red makes men feel more amorous - even if this is only on a subconscious level.
Their volunteers were told they had $100, shown the picture of their "date", then asked how much of that money they were prepared to spend.
On average, wearing red meant a more expensive night out, and in general, a higher rating of attractiveness.
When the pictures were shown to other women, there were no wardrobe-dependent differences in attractiveness ratings.
Professor Andrew Elliot, who led the research, published in the Journal of Personality and Social Psychology, said: "It's fascinating to find that something as ubiquitous as colour can be having an effect on our behaviour without our awareness."
Dr Jo Setchell, an anthropologist from Durham University, said that, as the colour of blood, red was the easiest signal for an animal to produce externally, and had become a handy method of advertising fertility.
"For example, a lot of female monkeys have bright red sexual swellings, which show that they are around the time of ovulation.
"There has been controversy over whether, in female humans, ovulation is advertised or not, although there is some evidence that behaviour, such as going out, changes around that time.
"But wearing red could give you an advantage."