People saw a new colour for the first time in 2025

In April, a team of researchers reported that a device allowed them to observe an intense green-blue color that had never been seen by humans before. After the announcement, they were bombarded with requests from the public to see the color for themselves.

The device could allow people with certain types of color blindness to have typical vision, and could even allow people with typical vision to perceive a wider range of hues. “We are very interested in expanding the dimensions of color experience,” says Austin Roorda of the University of Waterloo in Canada.

In most people, the retina at the back of the eye contains three types of cone cells – called S, M and L – that each detect light with a different range of wavelengths. Our brain creates our perception of colors based on the signals emitted by these three types of cones.

The range of the visible spectrum detected by M cone cells overlaps that of the other two types, so we do not normally receive signals from just M cells.

Roorda and his colleagues used a highly precise laser to specifically activate about 300 M cones in a small square area of ​​the retina. This patch corresponds to a part of the visual field equivalent to the size of your fingernail at arm’s length, explains Roorda.

When five of the researchers used the device, they saw a blue-green color more intense than anything they had seen before, which they named “olo.” This was verified using a color matching test where they compared olo with the entire visible spectrum shades.

“It was truly a mind-blowing moment,” says Roorda, who has seen olo more times than anyone, due to his key role in the system’s development. “The most saturated natural light seemed pale in comparison.”

After this achievement became a media sensation, the team received dozens of requests from people – including artists – wanting to view olo. But it takes several days to set up the system for a new person, so the team couldn’t afford to take them on, Roorda says.

Instead, they focus on two ongoing experiments. In the first case, they will test whether the device could allow colorblind people to temporarily benefit from typical vision. Some types of color blindness are caused by having only two types of cones instead of three. “We would play with certain cones belonging to a single cone type a little differently than others of that cone type, and we think that would send signals to the brain as if it were a third cone type,” Roorda says. The hope is that people’s brains interpret these signals as new colors they’ve never seen before, he says.

The team is also studying whether a similar approach could allow people with three cone types to experience the world as if they had four, which some people have naturally, allowing them to see a wider range of hues. The results of both experiments should be available next year, Roorda says.