Key Points
- Five people from two universities in the US were able to see a colour not usually visible to humans.
- Scientists made this possible by using lasers to optically stimulate individual photoreceptor cells on the retina.
- The previously unseen hue colour has been named 'olo'.
A new colour has been discovered, but so far, just five people in the world have been able to see it.
The colour was identified as part of research done at the University of California (UC), Berkeley in the United States and has been called 'olo'.
Those who viewed the colour described it as a blueish-green of unprecedented saturation.
How was olo discovered?
They were all participants who had laser pulses shot into their eyes as part of a scientific experiment.
This was done by "optically stimulating individual photoreceptor cells on the retina" through a system the researchers dubbed 'Oz'.
While the human eye has three types of cone cells — S, L, and M, with each one sensitive to different wavelengths of blue, red, and green, respectively — their spectral sensitivities overlap.
Cones convert light energy into electrical signals and specialise in sensing light that is responsible for colour vision and sharp, daytime vision.
According to the research paper, in normal vision, "any light that stimulates an M cone cell must also stimulate its neighbouring L and/or S cones", because its function overlaps with them.
However, through the use of the Oz system, the cones can be stimulated separately, "which in principle would send a colour signal to the brain that never occurs in natural vision".
"Theoretically, Oz expands the natural human colour gamut to any (L, M, and S) colour coordinate," the paper stated.
"Colour matching confirms that our attempt at stimulating only M cones displays a colour that lies beyond the natural human gamut."
The truest version of olo would therefore be defined as "pure M activation".
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Advancing research around colour blindness
The research paper suggests the Oz system, which discovered olo, may provide insight into the possibility of enabling a wider array of colour vision in people who are colourblind.
"Oz can be programmed to probe the plasticity of human colour vision," the paper said.
Seeing olo
While olo may become the most talked about colour this week, it is unlikely to become the any time soon, due to the fact it is inaccessible to the human eye without retinal stimulation.
Those who took part in the visual experiment and viewed olo were scientists, three from UC Berkeley who are co-authors on the paper and two from the University of Washington, who participated in the research.
It has been reported that the name 'olo' was chosen as it denotes the binary 010, indicating that of the L, M, and S cones, only the M cones are switched on.
'Open to argument'
Professor John Barbur, a vision scientist at the University of London in the United Kingdom, is reported to have said that while the research was a "technological feat" in stimulating selective cone cells, the discovery of a new colour was "open to argument".
Barbur, who was not involved in the experiment that identified olo, has said the perceived brightness of a colour may change depending on changes to cone sensitivity.
