This is a very very spooky illusion, I have no idea how it works. Something to do with your brain interpreting detail where there is none. Proof that you should never believe your eyes.Instructions:
1) Click the image to enlarge it
2) Examine the picture noting that the angry face is on the left.
3) Step backwards away from your monitor so that you are looking at the image from further away.Effect:
The faces appear to swap round!!!!!Click on the image to enlarge it to FULL SIZE