Scientists claim to have discovered a new colour that no human has ever seen before, a groundbreaking finding that has the potential to reshape our understanding of colour perception. The research, published in the journal Science Advances on Friday, April 18, 2025, introduces a colour named "olo," which participants described as a blue-green hue with a level of saturation that is "off-the-charts." This remarkable discovery was made possible through an innovative experiment involving laser pulses aimed at the participants' eyes.
The study's co-author, Professor Ren Ng from the University of California, Berkeley, expressed amazement at the findings, stating, "We predicted from the beginning that it would look like an unprecedented colour signal but we didn't know what the brain would do with it. It was jaw-dropping. It's incredibly saturated." Professor Ng, along with four other participants, all of whom had normal colour vision, experienced this new colour during the experiment.
To achieve this, researchers employed a device called Oz, specifically designed to manipulate the retina’s cone cells. The retina contains three types of cone cells—S, L, and M—each sensitive to different wavelengths of light. In normal vision, when light stimulates an M cone cell, it also activates neighbouring L and/or S cones. However, the Oz system selectively targets only the M cones, allowing for the perception of colours that do not occur in natural vision.
During the experiment, a laser beam was directed into one eye of each participant, stimulating the M cone cells exclusively. The research paper explained, "Oz stimulation can target light to only M cones and not L or S, which in principle would send a colour signal to the brain that never occurs in natural vision." This innovative approach enables the display of colours that lie beyond the well-known, bounded colour gamut of natural human vision.
Participants were asked to adjust a controllable colour dial until it matched their perception of olo. The researchers shared an image of a turquoise square to give a sense of the colour, but they emphasized that this representation does not fully capture the richness of olo. Austin Roorda, a vision scientist involved in the study, remarked, "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 absolutely pales by comparison with the experience of olo."
While the findings have been met with excitement, some experts remain cautious. Professor John Barbur, a vision scientist at City St George's, University of London, stated, "While the research is a technological feat, the discovery of a new colour is open to argument." He noted that the perceived brightness of colours can change depending on how cone cells respond, suggesting that the interpretation of olo might vary among individuals.
The implications of this research extend beyond mere curiosity about colours. Professor Ng highlighted the potential for future applications in understanding colour blindness. As the team continues to study their findings, they hope to explore how this new understanding of cone stimulation could help those who struggle to distinguish between certain colours.
The study involved five participants—four men and one woman—who were all co-authors of the research paper. Their unique experience of olo has sparked interest in the scientific community, raising questions about the limits of human colour perception. The researchers are clear, however, that this new colour cannot be seen in everyday life. As Ng pointed out, "We're not going to see olo on any smartphone displays or any TVs anytime soon. And this is very, very far beyond VR headset technology.”
As the research continues, the team aims to refine their methods and further explore the implications of their findings. The discovery of olo not only challenges our understanding of colour but also invites us to reconsider the boundaries of human perception. The excitement surrounding this breakthrough highlights the ongoing quest to uncover the mysteries of vision and the complex interplay between light, colour, and our sensory experiences.
In summary, the discovery of olo represents a significant milestone in the field of colour science. With the potential to enhance our understanding of human vision and colour perception, this research opens up new avenues for exploration and innovation. As scientists continue to investigate the implications of their findings, the world eagerly awaits what new insights may emerge from this fascinating study.
