Who's Hiding Here?

Look at the picture. Can you recognize what's there among all the spots?

At first glance, you see only black spots on a white background. Once you've discovered what's hiding there, it will never be hidden again among the spots.

Our perception doesn't depend only on the picture our eyes see. It also relies on what the brain "knows" and is looking for in that picture. The brain interprets the picture on the basis of the information stored in our memories.

Illusions like this one are examples of "top down" processes at work. Our memory allows us to easily connect the parts into a complete image. These processes can affect our perception of an ambiguous picture (like the one of the old woman/young woman).

Once you've identified the object in the picture, you won't be able to return to the previous situation in which you saw only dots. The experience you just had will stay in your mind forever. (Try looking at the picture again in another month or year.)

Links:
A demonstration on Dr. Michael Bach's extensive website on illusions (with hints if you need them):
http://www.michaelbach.de/ot/cog_dalmatian

More "Who's Hiding Here?" pictures:
http://www.moillusions.com/2006/05/spot-object-category.html

Related exhibit:
The Imaginary Triangle