Which is which, this or that?

Some illusions, like the ones below, still work no matter how well you understand what is going on. These are called “perpetual illusions” because they stick around even if you try to get rid of them. The images are referred to as ambiguous or unstable because they can correctly be interpreted in different ways and can appear to “switch” from one to the other, even while you look at them. This proves that the brain is constantly reanalysing information, even if it has processed the same information already. Not only does the brain continuously re-examine all the information it receives, it is capable of coming to different conclusions from identical signals.

What do you see?

Eskimo or American Indian?	Rabbit or Duck?

Goose or Hawk?	Faces or Vase?

Where's the front of each image? Can you make them “switch”?

Greeting Card	Schroeder's Staircase

Reversing Cube