Only Five People Have Seen the Color “Olo”

Researchers have identified a new, highly saturated color called “olo” that cannot be replicated on screens, accessible only to five individuals through precise retinal stimulation using advanced laboratory technology.

The discovery of “olo”

Only five people in the world have seen a color that cannot be displayed on any screen. Named “olo” by scientists, participants described it as having an intensity unknown in everyday life, while the rest of us can only imagine its appearance.

The experiment, published in the journal Science Advances, demonstrates the hidden complexities of human vision. Five participants experienced this color through specialized equipment that allowed scientists to manipulate the responses of specific retinal cells, rather than through any new pigment or light source.

Experimental methodology and participants

The study involved five individuals with normal color vision—four men and one woman—three of whom were co-authors of the publication. Notable participants included Austin Roorda, a professor of optometry and vision science at UC Berkeley, and Ren Ng, a professor of electrical engineering and computer science at the same institution.

The experiment did not use pigments or dyes. Instead, it required participants to look into specialized apparatus that used high-precision light to stimulate selected cells in the retina. James Fong, the lead author who proposed the name “olo,” did not actually participate in the testing group.

Describing the indescribable

Participants described “olo” as an exceptionally saturated blue-green color, with associations ranging from intense teal and turquoise to peacock feathers. However, none of these comparisons fully capture the experience.

While images labeled “olo” circulate online as bright turquoise or blue-green rectangles, they are mere approximations. Current display technologies cannot reproduce the specific retinal stimulation generated by the laboratory equipment used in the study.

Retinal stimulation and the Oz system

Human vision relies on three types of cones in the retina, denoted as S, M, and L. Natural light typically stimulates these cones simultaneously. The “Oz” technology allows researchers to map an individual’s retinal layout and send light doses to specific cells while tracking eye movements, effectively bypassing the natural blending of signals that limits how we perceive color.

The researchers confirmed the color was unique by having participants compare it to standard colors. To match the experience, participants had to adjust the saturation of standard colors by adding white light, supporting the conclusion that “olo” exceeds the saturation range of normal vision.

Scientific skepticism and the origin of the name

The term “olo” is derived from “0-1-0,” representing the experimental goal of minimal S-cone activity, high M-cone activity, and minimal L-cone activity. While the researchers define it as a “novel color,” some experts argue it is more accurately described as an extremely saturated variation of an existing color direction.

Regardless of the terminology debate, the study marks a significant technical achievement in manipulating photoreceptor activity. The “Oz” system continues to serve as a research tool for exploring the foundational mechanisms of human vision, though it remains restricted to laboratory environments for the foreseeable future.