The puzzling 'Benham's Disk' mystery: How does your brain trick your eyes into seeing colors that don't exist?

The "Benham disc" was first made in 1894 by the British inventor Charles Benham, who created it as an optical instrument, then it was turned into a toy, and it quickly attracted the attention of scientists who wanted to understand how the eye and brain perceive colors.

When the disk is stationary, you see just plain black and white graphics. But as soon as it spins, you begin to see arcs of red, blue and green colors, even though these colors do not actually exist on the disk.

This phenomenon, which has puzzled scientists for about 200 years, is known as “subjective color.”

In a new study, a team from the National Institute of Basic Biology in Japan showed this disc to an artificial intelligence system that they trained to guess the next images after watching nature videos. Even though the input images were black and white, the AI ​​predicted that colors would appear faded.

The researchers found that these colors produced by the artificial intelligence changed based on the colors of the moving objects it saw during training. This means that the brain links movement with color, and this connection is what makes you see colors that do not exist when the disc rotates.

Scientists now believe that this phenomenon does not only occur in the retina, but is related to how the brain predicts upcoming scenes based on its previous experiences. Simply put, your brain expects to see certain colors when it sees movement, even if those colors are not present.

The researchers say: “The study indicates that subjective color is linked to the brain’s function in predicting the future based on the past, and this provides a new explanation for the puzzle that has puzzled scientists for two centuries.”

Scientists hope that these results will help them understand more deeply how visual perception works.

The results were published in the journal Scientific Reports.