Our Flag’s True Colors?

The flag shown here may look strange. Here’s how to see its true colors.

Use a pen or pencil to make a small dot near the center of a blank sheet of white paper. Lay the paper aside. Now stare at the dot near the center of this flag while you slowly count to 30. Then quickly cover the flag with the blank sheet of paper. Stare at the dot on the paper.

The flag will appear on the blank paper, in its familiar colors: red, white, and blue.

How It Works
We asked Dr. Hugh Foley of Skidmore College to explain this effect. But he said he couldn’t. In fact, he said that no one knows the full explanation. Here’s what scientists do know. The back of the eye has many tiny light-sensing areas, which detect different colors of light. These sensors are hooked up in pairs: red with green, white with black, and blue with yellow. Each pair forms a channel of information that is carried to the brain. In each channel, the two colors seem to work against each other.

If someone stares at one color for a long time, the sensors for that color become overactive. That channel is “out of balance.” For some reason, as the channel bounces back, or “rebounds,” to become balanced again, messages for the opposite color also become active. “A lot of yellow light will cause the yellow-blue channel to be imbalanced,” Dr. Foley said. “That leads to a rebound toward blue.”

When we stare at the flag shown above, we move all three color channels off-balance. While they are rebounding, we can see the flag’s true colors.