Two pictures with the same face but with different contrast. In one you see a female in the other a male. Learning the tricks of visual perceptions surely helps visual artists.
….two pictures with the exact same face.
But … on one photo you see a girl and on the other one – a guy.
The fact is that this face was created on computer by mixing male and female face features, which gave this androgynous face. With a change of contrast, our brain recognizes the face on the left as being a female one, while on the second photo, where contrast is higher, our brain recognizes it to be a male’s face. For me, this is the best optical illusion of the century.
UPDATE: for some critical comments see: Reddit
It’s a cognitive illusion.
What you’re looking at isn’t an optical illusion, but is a play on the basic expected traits of men and women’s faces. The flusher lips of the left pic coincide with our expectations for women’s faces, as does the fairer skin. And it’s not just the illusion of lipstick; even without lipstick, we expect women’s lips to be more red than men’s. The difference in skin tone also brings to mind a recent a study suggesting that, on the whole, men’s faces are more red complected, while women’s are more green. Thus, even in the B&W photo, we infer that the darker complected face has the deeper reddish tone of masculinity; the lighter, the paler, greenish tone of femininity.
UPDATE: found original article: The illusion of sex, 2009 Third prize, Richard Russell, Harvard University, USA