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Bird in a Cage

Bird in a Cage
When your eyes adapt to color, you can see things that aren’t really there.

Stare at a bird’s eye for 30 seconds, then look into the empty cage. You’ll see a ghostly bird—of a very different color—inside the cage.

The Bird in a Cage exhibit in the Exploratorium's Central Gallery
An animated gif demonstrated the visual phenomena in the Bird in a Cage exhibit.
What’s going on?

The ghostly colored images you see, called afterimages, are the result of adaptation in the color-sensitive cells in your eyes.

There are three types of color-sensitive cone cells in your eyes; each responds to reddish, greenish, or bluish light. When you stare at the red parrot, your red-sensitive cones “get used to” the image and stop responding as strongly. When you suddenly look at a white background, the relatively strong response of your blue and green cones produces an image of a blue-green parrot.

Similarly, staring at a blue-green parrot will produce an image of a red parrot. In general, staring at any color will produce an afterimage that is that color’s complement, or opposite.