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Julie Hambleton
Julie Hambleton
May 11, 2024 ·  2 min read

This Blue or Green Illusion Depends On How Your Brain Perceives Color

Think you know the difference between blue and green? Think again! There is another optical illusion known as the blue or green illusion that is making people second-guess their own eyes. This is how it works. 

The Blue Or Green Illusion

Optical Express conducted a survey to see how people perceived color. They conducted a survey of 1,000 people with the blue or green illusion. First, they showed each participant a square that is one solid color. Each participant had to decide whether or not they thought the square was blue or green. Have a look at the image below and decide for yourself.

Image Credit: Optical Express

Read: Do You See A Duck Or A Rabbit? Your Answer Reveals Something About Your Brain

It’s About Perspective

After looking at the first image, 64% of the participants thought that the image was green and 32% saw blue. Next, the researchers showed the participants that same color square, only this time they displayed it in between two other squares, each very obviously different shades of blue. This caused the answers to change quite drastically: 90% of the participants said that the center square (the original color) was green. Check it out below and see what you think.

Image Credit: Optical Express

What Is The Real Color?

According to Optical Express, the RGB values of the color are 0 red, 122 green, and 116 blue. This places it in the green category as opposed to the blue. This is why, when placed next to two obviously blue color squares, it looks quite green. It does, however, have a high blue count, which means that when viewed alone some people may perceive it to be blue.

Why Do Some See It As Blue Vs Green?

Every person’s eyes and brains perceive colors slightly differently. This is why people see colors differently, among other things.

“Light is converted to an electrical signal which travels along the Optic Nerve to the Visual Cortex in the brain. The brain makes its own unique interpretation of this electrical signal,” explained Stephen Hannan, Clinical Services Director at Optical Express. “It is not surprising that many respondents changed their mind when seeing the color in contrast to the two blue shades, as we perceive an object’s color based on a comparison to its surrounding shades, not on the actual color itself.”

Stephen Hannan via The Daily Mail

This test and other similar ones can help predict whether or not someone is color blind. This condition can be hard to determine because it is impossible for us to see the world through someone else’s eyes. Depending on the severity, color blindness can have a big impact on someone’s life. It can affect their ability to have certain jobs and can also be a safety issue, depending on which colors they can and cannot see. If you suspect you might be color blind, book an appointment with an optometrist to have your eyes tested.

Keep Reading: A Third Person is Hiding in This Old Photo – Do You See Them?


  1. Is this BLUE or GREEN? Forget The Dress, there’s a new optical illusion dividing the web – but which colour do you see?Daily Mail. Kate Samuelson.