Researchers at UC Berkeley have discovered a new color outside the range of human color vision. Only five people in the world have seen this new color. They call the color “olo”.

According to The Atlantic, “The color “olo” can’t be found on a Pantone color chart. It can be experienced only in a cramped 9-by-13 room in Northern California. That small space, in a lab on the UC Berkeley campus, contains a large contraption of lenses and other hardware on a table. To see “olo”, you need to scootch up to the table, chomp down on a bite plate, and keep your head as steady as you can.”

Austin Roorda, a professor of optometry and vision science at UC Berkeley, demonstrates what it looks like to be part of the Oz experiment. Image credit: Austin Roorda, University of California, Berkeley.

Why the cramped room and complicated setup, you ask? To see this new color, your retina must be targeted by a laser with precise accuracy. The researchers created a special laser instrument, named Oz, that delivers light to only specific individual cells in your retina.

Here’s the closest approximation of the new color that we can see without the Oz system. It’s blue-green with unprecedented saturation.

The closest approximation of the new color. Image credit: BBC.

The Oz System

Your eyes see color using cone cells—L (long), M (medium), and S (short)—each sensitive to different wavelengths of light. Normally, these cones work together, blending inputs to create every color you’ve ever seen.

First, the researchers mapped a part of the retina to identify each cone cell as an S, M, or L cone.  Oz delivers light cell-by-cell to individual photoreceptor cells on the retina. They used precisely targeted laser pulses to stimulate just the M cones, while avoiding L and S cones.

The Oz software takes a color image (left column) and calculates which cone cells in the retina need to be activated for a person to see that image (center). It then calculates the pattern of laser microdoses that need to be delivered to the retina to activate those cones (right). Image credit: University of California, Berkeley.

This bypassed the usual overlapping input that your brain uses to construct color. By isolating the M cones, the brain receives an input combination that never naturally occurs, resulting in the perception of a color outside our typical visual spectrum.

“Olo” is named for its theoretical LMS color space coordinates for long-, medium-, shortwave cones: (0, 1, 0), representing the stimulation of only the green (M) cone in the human eye, with no stimulation of the red (L) or blue (S) cones.

Their research was published in Science Advances.

Proving “olo” is outside normal vision

To test if “olo” was truly beyond normal human color vision, researchers had participants compare it to a teal laser and adjust its saturation using white light. The researchers controlled the display on the RGB projector with  Psychtoolbox, a MATLAB community toolbox. When participants added white light to desaturate “olo”, it matched the laser—confirming “olo” exists outside the typical human visual range.

The study advances our understanding of color vision. The researchers hope to use this technique to further research color blindness.

To read the full research paper, see 10.1126/sciadv.adu1052.