Gaydar?

Humans are adept at rapidly drawing information about other people from the way they look. But is it possible to assess sexual orientation?

Can walking style give clues to sexual orientation? Using 3D motion capture systems borrowed from computer-generated animation in film-making, a US team recorded gay and straight men and women walking on a treadmill. The gay subjects had somewhat 'gender-incongruent' postures and walking styles. When students viewed animations of the backsides in motion, they were able to judge sexual orientation to some extent (60 per cent correct, compared with the 50 per cent expected by chance) - but only of men.

A 2008 study revealed that, to some degree, sexual orientation can be worked out from the merest glimpse of a face. When subjects were shown photos of 90 male and female faces for between 33 milliseconds and 10 seconds, just 100 milliseconds was enough for them to identify sexual orientation about 60 per cent of the time. Notably, accuracy did not improve after 100 milliseconds - a quick glance conveys all the information that the brain can decipher.

The study adds to evidence that the brain is extremely good at extracting information from faces. A classic study in 1994 discovered that judgements of teaching professors based on two-second video clips were remarkably similar to assessments made by students at the end of the course.

Image: John Wildgoose; Wellcome Images