Scientists have created a color that lies outside the range of normal human vision. Using laser pulses to stimulate specific cells in the retina, a team from UC Berkeley and the University of Washington successfully induced the perception of a novel hue — dubbed olo — in five volunteers. The researchers claim it’s a blue-green unlike anything previously seen, with an intensity so vivid that conventional screens or pigments cannot reproduce it.

What even is color?

We take it for granted because it’s all around us, but color is actually remarkably complex.

Color is a mixture of physics and how our brains perceive certain things. In physical terms, it is the result of electromagnetic radiation within the visible spectrum — wavelengths between roughly 400 and 700 nanometers — interacting with the eye. But we don’t see physics, we see through our eyes and brains.

When this light enters the eye, it stimulates cone cells in the retina, which come in three types: long (L), medium (M), and short (S), each tuned to different parts of the spectrum corresponding roughly to red, green, and blue. The brain interprets the relative activation of these cones as color. Every hue we perceive — from violet to scarlet — is constructed by comparing how strongly each cone type responds to incoming light.

This new study started with a simple question. What if you could interact with just one kind of cell in the eye, and not the others?

This is, of course, easier said than done. In natural conditions, stimulating just one type of cone, like the M cones, is impossible. Their sensitivity overlaps with both the L and S cones. Shine light that activates M cones, and you’ll always tickle the other cones as well.

This is where a device called Oz comes in.

The color wizard of Oz

Named after the Emerald City — because of course it is — the Oz device uses lasers, mirrors, and eye-tracking to direct microbursts of light precisely onto individual cones. The team mapped each participant’s retina in advance, classified their cone types using advanced imaging, and then fired laser pulses to stimulate only M cones, cell by cell.

There was no damage to the retina, as this was a low-power, carefully calibrated “microdose” of light. It’s a bit like touching a single pixel on a screen.

Because this pattern of stimulation — pure M cone input — never occurs in nature, the brain was forced to interpret a completely novel signal. What participants saw was a blue-green hue unlike anything they’d ever seen before.

The color that emerged was “a blue-green of unprecedented saturation,” said co-author Ren Ng. But trying to describe it misses the point. “There is no way to convey that color in an article or on a monitor,” said Austin Roorda, a vision scientist on the team.

The five people who saw it describe it as an extremely intense turquoise, highly saturated beyond anything we’ve seen. They tried to approximate it with something visible, but it’s only an approximation.

“The whole point is that this is not the color we see, it’s just not. The color we see is a version of it, but it absolutely pales by comparison with the experience of olo,” said Roorda for The Guardian.

How do you prove this worked?

This raises an interesting question: if color is a matter of perception, how can you prove these people saw a new color?

Researchers conducted rigorous color matching tests. Subjects compared olo to every visible shade they could reproduce using lasers and projectors. All found the same: they couldn’t match it without adding white to tone it down.

That alone, the researchers argue, is proof enough. In traditional color theory, if you need to desaturate a color to make it match something on the visible spectrum, you’re dealing with something beyond that spectrum.

“Subjects consistently rate olo’s saturation as 4 of 4,” the team wrote in the Science Advances paper. “Compared to an average rating of 2.9 for the monochromatic colors of matching hue.”

However, John Barbur, a vision scientist at City St George’s, University of London, who was not involved in the study, told the BBC while the research is a “technological feat” in stimulating selective cone cells, the discovery of a new colour is “open to argument”.

Does this matter?

Researchers say this is more than just a curiosity or a parlor trick. Programmable control over how we see colors is the “holy grail” of vision science, researchers say.

They believe the system could be used to simulate color vision for people who are color-blind, or even model what vision might be like with a hypothetical fourth type of cone — something that a small subset of women may naturally possess.

In other words, the technology could simulate not just olo, but an entirely new dimension of color perception. We could even get people to see colors that are beyond natural human capacity at some point in the future. That’s not just useful for science — it could, someday, change the way we see the world.

But don’t expect olo to show up on your phone or TV anytime soon.

“This is basic science,” said Ng. “And this is very, very far beyond VR headset technology.”