In one of the largest psychological studies ever conducted, an intriguing difference between male and female views on what is attractive has emerged. The study was recently published in the academic journal Aesthetic and Plastic Surgery and was conducted by Lukas Prantl, a cosmetic surgeon and psychologist Martin Grundl from the University of Regensburg in Germany.

Until now, researchers had been found women were very good at anticipating what female body shape men found attractive.

There is a psychological theory that it makes sense for women to correctly estimate what men find desirable, and for men to calculate accurately what women like. This allows both genders to assess their own relative attractiveness with respect to the "competition". Correct estimation permits better "matching".

For example, if you are "premiere league" in the good-looking divisions, psychological theory predicts you will tend to seek and find a prospect in the same club. Gross mis-matching in desirability seems to rarely happen, and this might be because it doesn't promote relationship longevity. A physically gorgeous person is surely likely to be seduced away from a less desirable mate, at some point in the future.

Prantl and Grundl argue that in Western cultures both sexes tend to agree a smaller female waist and relatively lower weight is more appealing. The main difference between men and women on the best female body shape has now been found, by this latest research, to be opinions about the ideal bust size.

Prantl and Grundl quote previous research which found over two decades, models in 'Playboy' magazine, who would be selected for male appreciation, had a much larger breast size in comparison to waist measurement, than models in Vogue, who would be chosen for female admiration.

A similar previous study found Playboy models tended to have the largest bust size while 'fashion' models the smallest. Yet another study cited by Prantl and Grundl, found 'pinup' girls in adult magazines for men in Japan, United States, and Germany sported larger breast sizes relative to waist measurements, than models and display mannequins, who should be designed to appeal to women.

Prantl and Grundl in their experiment used a web-based interface which allowed participants to manipulate the appearance of a woman's photographed figure by adjusting five sizes and shapes including weight, hip width, waist width, bust size and leg length. By clicking on a button, the photograph of the female figure changes its dimensions. Participants adjusted the woman's features until it matched their own beauty ideal.

A total of 34,015 participants - 16,686 men and 17,329 women aged between 15 and 98 years took part - rendering this one of the largest psychological studies ever.

The majority of men and women were found to prefer female figures of medium or low body weight with medium-sized hips and a narrow waist. However, a striking gender difference emerged over breast size, with 40% of men preferring a large bust size, in comparison to only 25% of women.

Prantl and Grundl argue that this difference between men and women is surprising because women theoretically ought to have the same beauty ideal as men. Men and women seeing eye to eye on what is attractive, allows them to judge their own relative desirability levels with respect to other men and women, and so match with the correct prospective mate.

Prantl and Grundl point out a woman with a large-sized bust who considers medium size as more eye-catching, naturally underestimates her own attractiveness to men, and hence 'undervalues' herself. It logically follows she will tend to be settle with a man of lower league desirability, so she is throwing away her advantages in the 'mating market place'.

One theory as to why women believe smaller breast size is more attractive, is that there appears a widespread prejudice that women with larger breasts are less intelligent and competent, and it could be women are keen to avoid this label.

Prantl and Grundl contend various previous studies have found the female curvaceousness ideal amongst women has declined, as more women entered the workforce, put greater store on careers compared to marriage, and pursued further education.

Prantl and Grundl argue that women today favour a more androgynous figure, or smaller breasts, since this might create an impression of career-relevant qualities such as intelligence and competence. Women also seem to not mind being so sexually attractive to men as they become more economically independent.

Another theory is women may prefer a medium-sized bust because they think that they are less likely to be ogled if they don't have big breasts, but a study using eye-tracking software found men spent just as much time looking at medium-sized as large breasts.

Perhaps it's as simple as women are more practical than men - bigger breasts are a challenge when it comes to finding clothing that fits well, or participating in sports and exercise.

Prantl and Grundl's experiment produced another intriguing finding. Only 11% of participants preferred a regular leg length in women, whereas 54% favoured a leg extent that in the case of a body height of 170 cm would correspond to a leg lengthening of 6 cm. This difference corresponds with the height of fashionable high-heeled shoes.

Prantl and Grundl point out that we already know models tend to have very long legs and, second, that high heels, which visually lengthen legs, are widely deployed by women to increase attractiveness. However, a longer leg length in relation to the torso is also associated with various important health outcomes, for instance, reduced risk of coronary heart disease, diabetes resistance, low blood pressure, better cardiovascular profiles, and considerably reduced risk of cancer.

This last result adds fuel to the debate over why we tend to find particular features of a body attractive. Evolutionary Psychology argues that we are driven by an evolutionary imperative to disseminate our genes as much and as widely as possible - so we are attracted to mates who look fit, because fitness on the outside suggests physical resilience and survival value.

By mixing genes with the strongest DNA out there, we give our progeny the best chance of survival.

This theory suggests that when you find yourself drawn to someone, you may think you are the victim of a poetic and mysterious process called falling in lust or love, but in reality, beneath conscious awareness, your genes are busy running cold calculations on who is hot, and who is not.