Washington, Aug 26 - Women find a combination of sex appeal and facial aesthetics irresistible in men, especially when they are looking out for potential mates, says a new study.

'We have found that women evaluate facial attractiveness on two levels -- a sexual level, based on specific facial features like the jawbone, cheekbone and lips, and a non-sexual level based on overall aesthetics,' said Robert G. Franklin.

Franklin is a graduate student of psychology at Penn State University.

'At the most basic sexual level, attractiveness represents a quality that should increase reproductive potential, like fertility or health.'

On the non-sexual side, attractiveness can be perceived on the whole, where brains judge beauty based on the sum of the parts they see. 'But up until now, this (dual-process) concept had not been tested,' Franklin explained.

Psychologists showed 50 heterosexual female college students a variety of male and female faces. They asked participants to rate what they saw as both hypothetical dates and hypothetical lab partners on a scale of one to seven.

The first question was designed to invoke a sexual basis of determining attractiveness, while the second was geared to an aesthetic one.