'Jaw-dropping': Scientists claim to have found never before seen colour 'olo', but not all are convinced

In a breakthrough that blurs the boundary of human perception, scientists in the US say they've discovered a colour never before seen by the human eye. During a daring experiment involving laser pulses aimed directly into the eye, researchers triggered a unique visual response — one that they believe unveils a previously inaccessible hue. They've named it “olo,” a blue-green shade so vivid that even the volunteers who saw it struggle to put it into words.

The research, published in Science Advances on April 18, explores how laser stimulation of individual cells in the retina can stretch the limits of visual perception. The team behind the study claims this method allowed participants to experience a new colour, dubbed "olo."

The five volunteers described the colour as “blue-green,” yet admitted the label fell short. “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,” Ren Ng, electrical engineer at the University of California, Berkeley, told The Guardian. “It was jaw-dropping. It’s incredibly saturated.”

The retina, located at the back of the eye, is packed with cone cells that interpret colour. Typically, the three types of cones — S (blue), M (green), and L (red) — overlap in their sensitivities, meaning natural light always activates multiple cones simultaneously.

But in this experiment, the laser precisely targeted only the M cones, isolating a signal the brain doesn’t usually receive. According to the researchers, this produced a colour experience outside the boundaries of natural vision.

To document their perception of “olo,” participants adjusted a dial to match the colour they saw during the laser stimulation.

Still, not everyone in the scientific community is convinced. John Barbur, a vision scientist at City, St George’s, University of London, dismissed the claims: “It is not a new colour. It’s a more saturated green that can only be produced in a subject with normal red-green chromatic mechanism when the only input comes from M cones.”