Scientists say they have discovered a 'new colour' never seen before by the human eye - calling the results 'remarkable'
22 April 2025, 22:00
Scientists claim to have discovered a 'new colour' never witnessed before by humans.
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The new discovery followed an experiment where researchers in the United States had laser beams shone into their pupils.
The results were published in the Science Advances journal.
The participants say they saw a 'blue-green' colour, which scientists have named "olo".
However, some critics say the discovery of a 'new colour' is "open to argument".
The co-author of the study, Professor Ren Ng from the University of California, said the findings are "remarkable".
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The findings may advance research into colour blindness, according to scientists behind the study.
Prof Ng told BBC Radio 4's Today programme that the 'new colour' olo was "more saturated than any colour that you can see in the real world".
He added: "Let's say you go around your whole life and you see only pink, baby pink, a pastel pink.
"And then one day you go to the office and someone's wearing a shirt, and it's the most intense baby pink you've ever seen, and they say it's a new colour and we call it red."
Five participants took part in the study: four male and one female.
All participants had 'normal' colour vision.
Three of the participants - including Prof Ng - were co-authors of the study.
The participants peered into a device named 'Oz' - made up of mirrors, lasers and optical devices.
The device was designed and updated by some of the researchers involved - a team of scientists hailing from UC Berkeley and the University of Washington.
The retina is a delicate, light-sensitive tissue located at the back of the eye. Its main function is to detect light and convert it into electrical signals.
These signals are sent to the brain through the optic nerve, allowing humans to perceive images and see the world around them.
The retina comprises cone cells - cells that 'perceive' colour.
Three types of cone cells are in the eye - S, L and M.
Each cone cell responds to a specific range of light wavelengths - some detect blue, others red, and others green.
The research paper explains that in normal vision, whenever an M cone is activated by light, nearby L and/or S cones are also triggered, since their functions overlap.
However, according to the study's findings, the laser only stimulated 'M' cones, "which in principle would send a colour signal to the brain that never occurs in natural vision" - the scientists said.
The results mean that olo can't be perceived by a human's naked eye without 'specific stimulation'.
To verify the colour seen during the experiment, the participants each used a controllable colour dial until it matched the new colour olo.
Austin Roorda, a vision scientist on the team, told the Guardian: “There is no way to convey that colour in an article or on a monitor.
"The whole point is that this is not the colour we see, it’s just not. The colour we see is a version of it, but it absolutely pales by comparison with the experience of olo".
Professor John Barbur, a vision scientist at City St George's, University of London, was not involved in the experiment. He told the BBC that while the study is a "technological feat" in stimulating selective cone cells, the discovery of the new colour is "open to argument".
He said that if, for instance, the red cone cells 'L' were stimulated in large numbers, people may perceive a "deep red" yet the perceived brightness may change due to differences in sensitivity to red cone cells.
Prof Ng stated the colour olo is "technically difficult" to see but said the results are promising.
According to the co-author, the team of scientists are studying the results to find out what it could mean for those with colour blindness and who struggle to identify different colours.
