By Joshua Tosin Ogunsakin 
A team of US scientists has claimed to have discovered a new colour, named olo, during an experiment involving the stimulation of retinal cone cells.
By firing laser pulses into the participants’ eyes, researchers triggered unique responses in M cone cells, leading to the perception of a blue-green hue. Published in Science Advances in April, the findings were described by co-author Prof Ren Ng as “remarkable.”
The experiment featured five participants, all with normal vision, who observed olo using specialised equipment called Oz, consisting of mirrors, lasers, and optical devices. According to the research, olo cannot be seen naturally in the real world without controlled stimulation of the retina.
Potential implications for colour blindness research
Prof Ng explained that olo is “more saturated than any colour that you can see in the real world” and compared it to encountering a new shade entirely.
He stated that this discovery could pave the way for advancements in understanding and treating colour blindness, where individuals struggle to differentiate certain colours.
The research paper noted that while M cone cells overlap functionally with neighbouring L and S cones during normal vision, the experiment isolated their response, producing a signal unseen in natural settings.
Debates and expert opinions surrounding the discovery
Despite its groundbreaking claims, some experts have voiced scepticism about the existence of olo. Prof John Barbur, a vision scientist at City St George’s, University of London, argued that interpreting the new colour is “open to argument.”
He acknowledged the technological achievement in selectively stimulating cone cells but suggested changes in cone sensitivity might affect perceived brightness, rather than defining a new hue.
Prof Ng admitted that witnessing olo requires specific technical conditions but underscored its significance for further study into vision and potential applications for colour vision impairments.
Discovery of colours
The discovery of colours has been a gradual process shaped by science, art, and human perception. Early humans identified basic colours from natural surroundings like the blue of the sky or the red of fire.
Over time, scientists uncovered the role of light wavelengths and cone cells in the retina, leading to a deeper understanding of how colours are perceived. The spectrum of visible light was formally categorised by Sir Isaac Newton in the 17th century, forming the foundation for modern colour theory.
From pigments in ancient art to advanced technologies uncovering new hues, the exploration of colour continues to evolve.