IS Sex just an Illusion

The only difference between these two faces is their degree of contrast. Yet one appears female and the other male. That's because female faces tend to have more contrast between the eyes and mouth and the rest of the face than male faces.

Richard Russell, the Harvard University neuroscientist who created the illusion, has previously found that increasing the contrast in female faces makes them more attractive. Conversely, reducing contrast makes a male face easier on the eyes.

Visit the Visual Illusion of the Year (2009) Competition and see if you have won