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Hall of Illusions


Applet design: V. Ramachandran

Programing: Akos Feher  Hidden Bird©1997 IllusionWorks, L.L.C.

 Hidden Bird

     Believe it or not, there is a bird hidden in this image. Can't see it?  Press the animate button and the bird will fly. However, once it comes to rest again it will disappear entirely.

What's Going On?

   This is a perfect example of camouflage. It is impossible for your visual system to establish a difference between the figure and the ground. Normally, the figure stands out from the ground.

      This demonstration shows how a common motion of a group of otherwise unrecognizable blobs is a very powerful cue for your visual system. It enables your visual system to realize that it's dealing with a single object. This effect is termed grouping. It is important that an animal can do this well, otherwise it might not easily spot a predator, prey or other  food, such as apples. Animals must be able to separate the figure from the ground. What we call camouflage is an attempt to deceive these processes.  A stalking cat moves cautiously and freezes from time to time to avoid giving motion clues to its prey. It has even been suggested that our good color vision evolved to enable our primate ancestors to spot colored fruit against a confusing background of green leaves. What gives us so much visual pleasure may originate as a device to spot our food and to break camouflage.

Entire web site©1997 IllusionWorks, L.L.C.