Have a look at the picture, closely. Now slowly back away from the screen... at about a metre away, two at the most, you'll see a very different image.
From MIT's Computational Visual Cognition Lab Gallery :
This impressive illusion created by Dr. Aude Oliva and Dr. Philippe Schyns, illustrates the ability of the visual system to separate information coming from different spatial frequency channels. In the ... image, high Spatial Frequencies (HSF) represent a woman w69, 243-ith a neutral facial expression, mixed with the low spatial frequency information from the face of an angry man.
And from the original research paper (PDF) :
The ... picture might be recognized as a face, as a female, as a young Caucasian face, as a non-expressive face, or as ‘Zoe’, if this was her identity.Definitely Zoe. She was always there, if you looked closely enough. :)