“Ollo” Observed: Scientists Reveal a Never-Before-Seen Color
In a breakthrough that challenges the boundaries of human visual perception, scientists in the United States have discovered a new color—one that the human eye has never naturally seen before. Dubbed “Ollo,” the newly identified color was revealed to five individuals through the use of lasers and advanced eye-tracking technologies, enabling them to perceive beyond the normal limitations of color vision.
The full study was published on April 18 in Science Advances, where researchers noted that the color could only be experienced through precise laser manipulation of the retina. As a result, those who saw it found it difficult to describe their experience in conventional terms.
Ren Ng, an electrical engineer at the University of California and a lead researcher on the project, told The Guardian, “We expected from the beginning that it would look like a signal of an unprecedented color, but we didn’t know how the brain would respond. It was dazzling. It was astonishing. It was deeply intense.”
Vision scientist Austin Roorda, a member of the research team, echoed this, stating, “There is no way to describe the color in a paper or display it on a monitor.” He further explained, “The color we normally see is not real. What we perceive is just a version of it, but compared to Ollo, it is completely faded.”
To help approximate the sensation of Ollo, the researchers shared an image of a turquoise square. However, they emphasized that this representation falls far short of capturing the color’s true intensity and depth.
Not all experts are convinced of the color's novelty. Professor John Barber, a vision specialist from St George’s, University of London, expressed skepticism about the findings. “The scope of this discovery is limited. It is not a new color. It’s a more saturated green that can only be created within a subject with a standard red-green chromatic process—when the input comes exclusively from the M-cones,” he explained.
Human color perception is rooted in three types of cone cells in the retina—long (L), medium (M), and short (S) wavelength-sensitive cones. Typically, natural light activates all three cones simultaneously. Red light stimulates the L-cones, blue light stimulates the S-cones, but due to its central position in the retina, the M-cone is not typically stimulated by natural light alone.
According to the research, while Ollo’s hue remains within the blue-green spectrum, its extreme and unusual saturation sets it apart. “In our prototype system, Ollo appears as a kind of blue-green against a neutral gray background, but with unprecedented saturation,” the researchers noted. To find a comparable monochromatic color, they had to reduce Ollo’s intensity by adding white light, proving it lies outside the bounds of familiar colors.
Participants in the study suggested names such as “teal,” “green,” “blue-greenish,” and “green with a hint of blue” when asked to describe Ollo. The scientists consistently rated Ollo’s saturation as 4 out of 4, whereas the average saturation rating of similar monochromatic colors was only 2.9.
This discovery, while still debated, opens new possibilities for exploring the limits of visual perception and how the brain interprets stimuli that fall outside the ordinary sensory range.
