The colour red has long been associated with women's sexual attractiveness, but a new study at the University of Kent has shown that this is not linked to any association in men's minds with the redness of women's genitalia.

A common view in popular discussion is that human males have a biological predisposition towards the colour red -- making it a very significant or 'salient' sexual factor because it makes them think about female genitals and sexual arousal. It has also been suggested that woman wear red lipstick to attract men by making them think about sexually aroused labia.

To test this hypothesis, a team from the University's School of Anthropology and Conservation generated 16 images of female genitalia by manipulating four individual photographs of the human female vulva to produce four subtle, yet different, colour conditions ranging from pale pink to red.

These images were then presented to 40 heterosexual males with varying levels of sexual experience who were asked to rate the sexual attractiveness of each image.

The results showed that the men rated the reddest shade significantly less attractive than the three pink shades, among which there were no significant differences in rated attractiveness.

Dr Sarah E. Johns, lecturer in evolutionary anthropology and lead researcher in the study, said: "Our results really challenge the commonly held view that the colour red promotes sexual attractiveness by acting as a proxy for female genital colour.

"We found in fact that men showed a strong aversion to redder female genitals. This study shows that the myth of red as a proxy for female genital colour should be abandoned. This view must be replaced by careful examination of precisely what the colour red, in clothing, makeup, and other contexts, is actually signalling to men. What it isn't signalling is female sexual arousal.

"Our findings have important ramifications for the future study of the role of colour signals in human social and sexual interactions," she said.

The research team also included Lucy A. Hargrave and Dr Nicholas E. Newton-Fisher of the School of Anthropology and Conservation. The study is published in the journal PLoS ONE.