Credit: WELLCOME INSTITUTE LIBRARY, LONDON

Imagine you are going overseas and wish to have a portrait done as a gift for your family. You want them to remember you as warm-hearted and affectionate. How would you pose?

This question was put to 165 psychology students by Michael Nicholls and colleagues, who report in Proceedings of the Royal Society (266,1517-1522; 1999) that most of the students posed with their left cheek turned towards the camera. When asked to try and look unemotional and intelligent, however, the students were more likely to present their right cheek.

The authors found a similar leftward bias in portraits by a number of artists. They believe that, in informal portraits, sitters present their left cheek because this side of the face is controlled by the 'emotive' right cerebral hemisphere. But when Nicholls et al. looked at portraits of scientists, such as the one of Louis Pasteur shown here, they found the right cheek turned towards the artist in every single case.