London: Scientists have developed a new method based on artificial intelligence (AI) for mapping the dynamics of a smile that can automatically distinguish between men and women.
Researchers from the University of Bradford in the UK mapped 49 landmarks on the face, mainly around the eyes, mouth and down the nose.
They used these to assess how the face changes as we smile caused by the underlying muscle movements - including both changes in distances between the different points and the 'flow' of the smile: how much, how far and how fast the different points on the face moved as the smile was formed.
They then tested whether there were noticeable differences between men and women - and found that there were, with women's smiles being more expansive.
"Anecdotally, women are thought to be more expressive in how they smile, and our research has borne this out. Women definitely have broader smiles, expanding their mouth and lip area far more than men," said Professor Hassan Ugail from the University of Bradford.
For the study, published in The Visual Computer: International Journal of Computer Graphics, the researchers created an algorithm using their analysis and tested it against video footage of 109 people as they smiled.
The computer was able to correctly determine gender in 86 per cent of cases and the team believe the accuracy could easily be improved.
"Because this system measures the underlying muscle movement of the face during a smile, we believe these dynamics will remain the same even if external physical features change, following surgery for example," Ugail said.
"This kind of facial recognition could become a next- generation biometric, as it's not dependent on one feature, but on a dynamic that's unique to an individual and would be very difficult to mimic or alter," he added.