The colour nobody should see

Scientists tricked human eyes into seeing a new colour called “olo.” It lives between red and green, where biology says no colour should exist.

(as close as experts think we can get to seeing olo ... without lasers)

Impossible made visible

Seems we were wrong about the limits of sight.

Researchers at the University of California Berkeley have coaxed human eyes into seeing a colour that shouldn’t exist.

The new hue, dubbed olo, sits somewhere between red and green — a combination our visual system normally forbids.

Five volunteers viewed it after scientists used precision lasers to stimulate red- and green-sensitive cone cells simultaneously.

When balanced just right, the conflicting signals fused into a totally new perception.

“It wasn’t like anything I’ve ever seen. You can’t describe it using words we already have.”— Allison Nagel, vision scientist

Colour me bad

Human eyes have three cone types: red, green and blue.Our brains compare their outputs to generate the rainbow of hues.Red-green signals usually cancel each other, which is why “reddish green” doesn’t exist.

Fun fact: about half of all women carry two slightly different red-cone genes, letting them distinguish more shades of crimson and coral than most men ever will.The trade-off? Men are sixteen times more likely to be colour-blind. So if olo looks extra fabulous, odds are she’ll notice first.

But by targeting single retinal cells with lasers, the team bypassed the brain’s veto.Each cone saw what it wanted, and the brain simply accepted it.Physics and perception drifted apart, and in that brief moment five people saw a colour no human was ever meant to see.

Yolo … olo!

The new colour only lasts while the lasers fire.There’s no pigment, wavelength or screen capable of displaying olo. It exists solely in the mind — an optical hallucination grounded in physics.

“This discovery reminds us that colour isn’t out there in the world,” said cognitive neuroscientist Tom Baden of the University of Sussex, “it’s an invention of the brain. And apparently a negotiable one.”

Let’s see where this goes

This work could reshape how we build AR displays, test vision disorders, and study the neural code of perception. It also reminds us that reality isn’t fixed — it’s constructed.

And sometimes, it can be hacked with a laser.

-Adam S