Researchers at two universities have found what they consider to be "the golden ratio" -- or perfect distances -- between a woman's eyes and mouth that determines whether she is thought to be beautiful.

The Toronto Star, reporting on the work of psychologist teams at the University of Toronto and the University of California, San Diego, worked out the exact ratio:

The distance between the eyes and mouth is 36% of the depth of the face while the perfect distance between the middle of the eyes should be 46% of the width of the face.

The study appears in the journal Vision Research.

To conduct the research, the university psychologists used Photoshop to alter the facial distances of eyes and mouth on photographs of women, then asked students to rate what they considered to be attractive.

"Our study conclusively proves that the structure of faces – the relation between our face contour and the eyes, mouth and nose – also contributes to our perception of facial attractiveness," said Kang Lee, the lead author of the study, the Star reports.

Lee says the findings explain why an attractive person sometimes looks unattractive, and vice versa, after a haircut "because hairdos change the ratios."

Using the formula, the BBC says, Canadian singer Shania Twain is a perfect fit and British actress Elizabeth Hurley comes close. Angelina Jolie, however, doesn't make the cut.

The Star quotes Pamela Pallett, of the UC-San Diego, as saying the researchers found the perfect face in British singer Cheryl Cole.

(Posted by Doug Stanglin)