Scientists say women are more attuned to get biologically relevant information in sweat that may guide them in choosing a mate.

But where men are concerned, their olfactory sense can be bluffed most of the time, said Charles J. Wysocki, behavioural neuroscientist at Monell Chemical Senses Centre, who led the study.

In the study, women and men rated the strength of underarm odours, both alone and in conjunction with various fragrances. The fragrances were selected to test their ability to block underarm odour through a method known as cross-adaptation.

Olfactory adaptation refers to the loss of sensitivity to an odour when one is constantly exposed to it. Olfactory cross-adaptation occurs when the nose adapts to one odour and then becomes less sensitive to a second odour.

Sniffed alone, the underarm odours smelled equally strong to men and women. When fragrance was introduced, only two of 32 scents successfully blocked underarm odour when women were doing the smelling.

Conversely, 19 fragrances significantly reduced the strength of underarm odour for men.

Wysocki noted that in earlier studies, men and women did not differ in their ability to cross-adapt to odours not from the body.

"Taken together, our studies indicate that human sweat conveys information that is of particular importance to females. This may explain why it is so difficult to block women’s perception of sweat odours," he said.

"Men and women differ in how they perceive body odours from both their own and the opposite sex," said Monell scientist George Preti, the analytical organic chemist who co-led the research with Wysocki.