The Science Behind The Viral Illusion That Claims To Show A "New Color"

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A classic optical illusion is going viral once again after it was recently shared on TikTok, blowing the minds of millions of new people. It’s widely known as the “true cyan color illusion” and is often said to reveal a color your eyes have never seen before. That claim is a little bit misleading, but the illusion does highlight some pretty weird and interesting truths about the nature of perception and color.

Here’s how it goes: you simply stare at the dot inside a red circle (try it in the video below) for at least 30 seconds, then close your eyes tightly. If you’ve followed the instructions right, you should see a glowing light blue orb. The color of this orb is, in fact, true cyan. 

Despite the way this illusion is often presented, cyan is a “real” color that you've perceived before. However, it’s true most TV screens, smartphones, and computer monitors aren't capable of producing this color in its purest sense. Most screens use red, green, and blue pixels set to varying intensities to create all the color combinations that we see, known as the RGB color model. When we see cyan on a screen, we are most often seeing two green and blue pixels next to each other, giving them the impression of cyan. However, that’s also true of any color that isn’t pure red, green, and blue. For example, orange is also just a subtle blend of red with a few green pixels. 

Nevertheless, you may still be wondering: why does staring at a white dot in a red circle make you see a cyan-colored orb when you shut your eyes? This “afterimage” is actually the result of residual activity of the nerve cells on the back of your eye. 

Most humans perceive color through three types of cone cells in the retina, each of which responds to different wavelengths of light. If you stare at a bright color (red, for example) for some time, the cones responsible for picking up on red will eventually become overstimulated, depleted, and desensitized. When you look away, the least depleted cones cells remain “fully charged” and overcompensate for the depleted cones cell, resulting in the perception of an image with reverse colors to the original.

Explaining the phenomenon of “afterimages” to IFLScience in 2018, Ajay Kuriyan, an ophthalmologist and retina specialist at the University of Rochester Medical Center, said: "If you stare at a color for some time, the cone cells responding to that color become refractory for a short period of time so the other color cone cells become stimulated. This is the principle that drives the afterimage.”

So, there you have it. While the optical illusion doesn’t actually allow you to “see a color you’ve never seen before,” it does highlight some pretty strange insights into our perceptions.


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