Beauty is in the eye of the beholder, even if the beholder is a robot. Amit Kagian from Tel Aviv University has taught a computer to recognise attractive women using a combination of psychology and maths.

Men and women were asked to rate the beauty of 100 different faces. The results were fed into a computer which mapped the geometric shape of facial features mathematically. The computer also looked at the hair colour, smoothness of skin and face symmetry to work out a formula for beauty. Once the machine had learned the components of a pretty face, it was tested with a fresh set of faces. Amit Kagian was happy with the success of his experiment. "The computer produced impressive results – its rankings were very similar to the rankings people gave" he said.

A possible next step is to teach computers how to recognise good looking men. This will be more difficult as psychological research shows there is less agreement about what defines male beauty. Amit Kagain jokes that his own portrait will not be part of the experiment “I would probably blow up the machine”.