A group of scientists in the US claim they’ve discovered a brand-new colour no human has ever seen before.
Nicknamed “Olo”, the colour showed up during a bold experiment where laser pulses were fired into volunteers’ eyes, carefully targeting just one type of cone cell in the retina. It led the participants to witnessing a striking blue-green shade that doesn’t appear in nature – and can’t be seen without special lab equipment. The research, published in the journal Science Advances on Friday, has been described as “remarkable” by co-author Professor Ren Ng the University of California. He told BBC Radio 4’s Today Programme that Olo is “more saturated than any colour that you can see in the real world“.
“Let’s say you go around your whole life and you see only pink, baby pink, a pastel pink”, he explained. “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 people – four male and one female – with normal colour vision took part in the study, including Prof Ng himself.
There are three types of cone cells in the eye – S, L and M – and each have varied sensitivities for wavelengths of blue, red and green respectively. Using a device called Oz – a setup of lasers, mirrors and optical components – the team from UC Berkeley and the University of Washington managed to isolate and stimulate just the M-cones, which are the cells in the eye that detect green.
Normally, these cones work in groups, overlapping with others so colours blend. But by activating only the M-cones, researchers triggered a colour signal that the brain doesn’t usually receive – and out came Olo.
This would in principle “send a colour signal to the brain that never occurs in natural vision”, the paper said. To confirm what they were seeing, participants adjusted a digital dial to match the new hue, and everyone agreed it was completely unlike anything they’d ever seen before.
But not everyone is ready to call Olo a new colour. Professor John Barbur, a vision scientist at City St George’s University of London, called the experiment a “technological feat”, but said whether Olo counts as a brand-new colour is “open to argument”.
He explained that stimulating cones in unusual ways can shift how we perceive brightness and colour – which could explain what happened in the study. Even so, the team is optimistic.
They believe their discovery could help future research into colour blindness and push the boundaries of what we understand about human vision.
Prof Ng admits Olo is “certainly very technically difficult” to see, but says this experiment proves the brain might be capable of processing colours far beyond what we see in everyday life.
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