To find out if this really were true, Dr Ben Jones in the Face Research Laboratory at the University of Aberdeen and a team of researchers carried out a study that involved volunteers looking at four different sets of digital images -- women looking happy, women looking disgusted, men looking happy and men looking disgusted.

In each case, the boffins paired together images that were identical except that in one the person was looking directly at the camera and in the other their gaze was averted.

The volunteers were then asked to rate the relative attractiveness of the images in each pair.

The researchers found that attraction is based on social cues that say, "I'm interested in you", the most important one being someone looking directly at you.

Based on the volunteers' input, the team found that a direct stare is attractive only if the person giving it looks as if they like you.

This preference was even higher if the face in the picture was of the opposite sex.