Sandbox

by Interesting Facts was written by Michael Nordine

Scientists have discovered a new color only five people have seen. If you’ve never heard of olo, there’s a good reason for that: You’ve almost certainly never seen it either. The new color, described as a “blue-green of unprecedented saturation,” has been seen by only five people in a laboratory setting, as it’s beyond the range of normal human visibility. Researchers discovered the teal-like hue by stimulating the M cone in subjects’ retinas with a laser device called an Oz, which allowed them to see a color said to be more saturated than any found in the natural world. 

The retina has three cones — L detects long wavelengths, M detects medium wavelengths, and S detects short wavelengths — that typically overlap to a certain degree. By using the Oz, scientists were able to activate the M cone in isolation, making it possible to see a color never perceived by humans before.

“It was jaw-dropping. It’s incredibly saturated,” said Ren Ng, an electrical engineer at the University of California, Berkeley, who both co-authored and participated in the study, in an interview with The Guardian. “We predicted from the beginning that it would look like an unprecedented color signal, but we didn’t know what the brain would do with it.” 

Researchers believe, or at least hope, that the science that enabled the participants to see olo could one day help people with red-green colorblindness experience the full spectrum of color.

Only five people have seen olo, but it’s possible quite a few hummingbirds have seen it. They can perceive colors we can’t, thanks once again to cones. Whereas our three color-sensitive cone cells enable us to see red, green, and blue light, hummingbirds (and most other birds) have a fourth type of cone attuned to ultraviolet light.

In addition to UV light, birds may even be able to see combination colors such as ultraviolet+green and ultraviolet+red — something we humans can only imagine. Having four types of cone cells, known as tetrachromacy, is also common in fish and reptiles, and researchers believe dinosaurs possessed it as well. It’s also present in some people, though the condition isn’t well understood and scientists disagree over how common it is.