Benham’s disc

Optical illusions

Benham’s disc – this spinning black and white pattern makes you see imaginary colors

• If the disk is spinning, turn the knob to make it stop. Notice that the pattern on the disk is black and white.
• Increase the disk speed and notice that you see colors on the disk. Experiment with the speed and direction controls to see how they affect the colors
• Ask other people what colors they see.

What’ is going on
Different people see different amounts of yellow, red, green, purple and blue on this spinning disk. Just why some people see color is not fully understood, but the illusion must involve the color vision cells in your eye. The sells come in three varieties. Some are most sensitive to red light, some green light, and some blue light. These different types of color sensors responds at different rates.

When you gaze at one place on the spinning disk, you are looking at alternating flashes of black and white. You see white only when all three color sensors respond to a flash of light. If one type of color sensor responds at a different rate than the others, you see the illusion of color. This spinning disk would appear colored even on a black-and-white television set.

Learn more…

Developed by the GE Volunteers in partnership with the Museum of Arts and Sciences (MOAS) – Daytona Beach, FL