Researchers May Have Found A New Color!
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Just when it seemed every color under the sun had been named, researchers at the University of California, Berkeley, have identified a new one. Called “olo,” this shade lies outside the normal range of human vision. It can only be seen under specific conditions using a laser. The five people who have seen "olo" describe it as a "blue-green of unprecedented saturation."
Before exploring how "olo" can be seen, it is helpful to understand how humans perceive color. The human retina contains three types of cone cells, each sensitive to different wavelengths of light. L cones detect long wavelengths (reds), M cones respond to medium wavelengths (greens), and S cones pick up short wavelengths (blues).
While each cone is most sensitive to its main color, it also responds to nearby colors on the spectrum. The M cones, which detect green light, sit in the middle. Because of this, when green light activates the M cones, some of that light often spills over and partially activates the L and S cones too. It is like pouring water into the middle of three side-by-side cups and seeing a bit splash into the ones on either side. This overlap helps the brain blend colors and lets us see thousands of different shades!
"There’s no light in the world that can activate only the M cone cells because, if they are being activated, for sure one or both other types get activated as well," says study co-author Ren Ng.
The researchers wondered what would happen if they could turn on just the M cone without affecting the others. To try this, they built a special device called "Oz." It uses a very precise laser to activate just one cone cell in the eye.
"The name comes from The Wizard of Oz, where there’s a journey to the Emerald City, where things look the most dazzling green you’ve ever seen," Ng explains.
The team recruited five people to test Oz. Three, including Ng, were part of the research team and knew its purpose. The other two were outsiders with no knowledge of the study’s goals. This helped ensure their opinions were not influenced.
The scientists began by mapping the individual cone cells in each participant’s retina. They then used Oz to stimulate only the M cones and asked the participants to describe what they saw. All five reported seeing a green color that was more vivid and saturated than anything found in the natural world. No digital display can reproduce the exact shade. But the closest approximation (image above) was an intense teal or bluish-green.
The study's findings, published in the journal Science Advances on April 18, 2025, have sparked global interest among researchers. Andrew Stockman, a vision scientist at University College London, believes the discovery could one day help people with red-green color blindness experience normal vision.
However, John Burbur at the University of London, is not convinced that "olo" is a new color. He believes it is just a very bright green that shows up when the M cones are the only ones receiving light.
Resources: Smithsonianmag.com, Scientificamerican.com, NewAtlas.com
