A small experiment has found that people are quicker to categorize a face as being male when it is shown to the left side of the brain. 

The conclusion was drawn from an analysis of responses from 42 volunteers who were asked to focus on a cross in the center of a computer screen. They were then shown faces, which were morphed from 100 percent male to 100 percent female across 280 trials, and were asked to categorize the faces as either female or male as quickly as possible. 

When an image was presented to the left side of the brain, it was generally considered more male, even though it was correctly perceived as more female when presented to the right side of the brain. 

Previous research has claimed that English language speakers place males ahead of females in sentences, in part due to gender stereotyping. When describing romantic couples, people name the partner perceived to be more masculine first, whether they are describing a heterosexual or same-sex couple - for example, 'Romeo and Juliet' and 'Adam and Eve'. The new study, which was carried out in English on English-speaking volunteers, showed that a bias to perceive faces as male in the English language affects the way that we perceive other people's faces, because the left side of the brain is the side which processes language. 

"Our study clearly found that people are much more likely to make a quick decision that a face is male when it is shown to the left-hand side of the brain," said lead author and psychology graduate student Sapphira Thorne from the University of Surrey. 

Citation: Thorne, S., Hegarty, P.,&Catmur, C., 'Is the left hemisphere androcentric? Evidence of the learned categorical perception of gender', Laterality. (in press)