Scientists have found that female portraits show a significant bias towards the left side of the face, which they believe is evidence of an expressive divide between the sexes.
The Mona Lisa is the most famous example of a woman who preferred to face the world with her left cheek, whereas men, such as Albert Einstein, whose portrait is displayed in the Royal Society in London, turned their right cheeks.
Researchers from the University of Melbourne in Victoria, Australia, reviewed nearly 1,500 painted portraits in addition to scores of facial photographs and found that 68 per cent of women and 56 per cent of men sat showing off their left cheeks.
A team led by Michael Nicholls, a psychologist, concluded that the explanation lies with the fact that the right, "emotive" part of the brain controls the left side of the face.
"When we asked people to portray as much emotion as possible when posing for a family portrait, they tended to present the left side of their face. When asked to pose as scientists and avoid portraying emotion, participants tended to present their right side," the team reported in the journal Proceedings of the Royal Society of London B.
The researchers dismissed suggestions that the left-sided facial bias can be explained by many portrait artists being left-handed, as they found the same bias for right-handed artists.
It is well established that self-portraits show a bias in the opposite direction, but the researchers believe that this is because the artist is looking in a mirror, which reverses right and left.
"When people express an emotion, the muscles of the left side produce a more intense expression than those on the right side of the face," the scientists say. "This asymmetrical expression presumably reflects the fact that the left side of the face is controlled by the right cerebral hemisphere, which is dominant for emotional expression."
The scientists cite research showing that men are less inclined than women to portray emotion openly. "Thus, women may be more likely to present their left, emotive cheek when sitting for their portrait," they say.
"Males, on the other hand, may be more inclined to turn their right (impassive) cheek."Reuse content