A team of scientists claims to have discovered a new colour, named “olo,” that no human has ever seen before. The research is based on an experiment in which researchers from the United States used pulsed laser beams directed into participants’ eyes.
By stimulating specific cells in the retina, participants reported perceiving a blue-green colour that they said they hadn’t seen before. Scientists have dubbed this allegedly new colour ‘olo,’ though some experts have said that the existence of a new colour remains “open to debate,” the BBC reports.
The findings, published Friday in the journal Science Advances, have been described as “remarkable” by study co-author Professor Ren Ng of the University of California, Berkeley. The results could help advance research into colour blindness.
Professor Ng, who was one of five participants in the experiment, said on BBC Radio 4’s Today programme on Saturday that ‘olo’ was “more saturated than any colour you can see in the real world.”
“Let’s say you spend your whole life seeing only pink, pale pink, a pastel pink,” he explains, “and then one day you go into the office and someone is wearing a shirt that’s the hottest pink you’ve ever seen, and they say ‘It’s a new colour and we call it red.’” During the team’s experiment, researchers shone a laser beam into the pupil of one eye of each participant.
There were five participants in the study—four men and one woman—all with normal colour vision. Three of the participants—including Professor Ng—co-authored the research article.
According to the study, participants peered inside a device called Oz, which consists of mirrors, lasers, and optical devices. The equipment was previously designed by some of the researchers on this project—a group of scientists from UC Berkeley and the University of Washington —and was updated for this study.
The retina is a layer of light-sensitive tissue located at the back of the eye, responsible for receiving and processing visual information. It converts light into electrical signals, which are then transmitted to the brain via the optic nerve, allowing us to see.
The retina contains cone-shaped cells, which are responsible for colour perception. There are three types of cone cells in the eye: S, L, and M, and each is sensitive to different wavelengths: blue, red, and green, respectively.
According to the study, in normal vision, “any light that stimulates an M cone cell must also stimulate its neighboring L and/or S cones,” because their functions overlap.
However, in this experiment, the laser stimulated only M cells,”which, in principle, would send a colour signal to the brain that never occurs in natural vision,” the article notes.
This means that the colour “olo” cannot be seen with the naked eye in the real world without the aid of specific stimulation. To verify the colour observed during the experiment, each participant adjusted a controllable colour dial until it matched.
Some experts, however, claim that the new perceived colour is a “matter of interpretation.”
Professor John Barbur, a vision scientist at St George’s, University of London, who was not involved in the study, said that while the research was a “technological feat” in selectively stimulating cone cells, the discovery of a new colour was “open to debate.”
He explained that if, for example, red cone (L) cells are stimulated in large numbers, people would perceive “an intense red,” but the perceived brightness can vary depending on changes in the sensitivity of the red cone cells, something not unlike what occurred in this study.
However, Professor Ng, a co-author of the study, admitted that while ‘olo’ is “certainly very difficult to see from a technical point of view,” the team is studying the findings to explore what they could potentially mean for people with colour blindness, who have difficulty distinguishing certain colours.