In a nutshell
- Scientists at UC Berkeley have developed “olo,” an entirely new color that falls outside the spectrum of what can be naturally seen by humans. They achieved this by specifically stimulating individual light-sensitive cells within the eye.
- The “Oz” technology circumvents the constraints of normal sight by stimulating solely the M-type cone cells in isolation, a process that doesn’t occur under regular lighting conditions.
- The participants characterized olo as a vividly intense blue-green hue that needed the addition of white light for accurate comparison with standard colors, indicating it lies beyond the spectrum of typical hues we encounter naturally.
BERKELEY, Calif —
Researchers from UC Berkeley have accomplished what was once thought unachievable – they’ve developed a hue that transcends the normal spectrum perceivable by humans. This groundbreaking color, named “olo,” presents itself as a strikingly vivid blend of blue and green, unlike any shade previously witnessed by human eyes.
The advancement originates from a novel technology and concept known as “Oz,” enabling scientists to accurately activate single photoreceptor cells within the human eye, thereby circumventing the usual limitations that constrain our ability to perceive colors.
Participants in the study described seeing “an extraordinarily saturated blue-green,” a color signal that does not typically appear in nature.
human vision
Because it arises from activating just a single kind of cone cell, something once considered unachievable.
The human eye has three kinds of cone cells — L (long), M (medium), and S (short) — which respond to varying wavelengths of light. The brain then processes this information to create vision.
experience of color
By analyzing the collective response of these cones, yet due to overlapping sensitivities, no individual type of cone gets fully isolated under typical circumstances.
This overlapping causes a basic limitation on the spectrum of colors we can perceive. However, what if we were able to activate only one type of cone cell at once?
Breaking the Color Barrier
The research team addressed this issue by creating an advanced system that employs adaptive optics along with rapid laser pulses to activate single cone cells. Following the mapping and categorization of numerous cone cells in the subjects,
retinas
The team utilized their Oz prototype to accurately target M-cones exclusively with light.
There isn’t any light frequency that can activate solely the M cones,” stated lead researcher Ren Ng, a professor at Berkeley, in an interview. “This made me wonder how it might appear if we could exclusively stimulate these M cone cells. Could it resemble the most vivid green imaginable?
More than 200 color coordination trials involving five subjects showed an intriguing finding: stimulating just the M-cones caused individuals to perceive a striking, unusual turquoise hue that couldn’t be replicated through traditional lighting.
“It was like a profoundly saturated teal … the most saturated natural color was just pale by comparison,” said Austin Roorda, a professor of optometry and vision science at UC Berkeley’s Herbert Wertheim School of Optometry & Vision Science, and one of the creators of Oz.
To verify whether this novel shade called “olo” genuinely falls outside our typical visual spectrum, participants attempted to replicate it through conventional techniques. However, they managed to achieve an approximation solely by incorporating white light to lighten it—strong evidence suggesting that “olo” extends beyond the usual scope of colors perceivable by humans.
Future Implications
The present iteration of the Oz system operates solely within a limited section of the retina, slightly away from the direct focal point, necessitating steady fixation from participants. To enable unrestricted eye movements or to encompass broader sections of the visual field, the system would need to map numerous additional cone cells and significantly enhance its capabilities.
processing power
.
Nevertheless, this study, which was published in
Science Advances
, represents a significant progression in the field of science.
vision
By manipulating single photoreceptors in real time, researchers have developed an entirely new type of visual encounter—a peek into a novel perceptual realm.
into colors
that were previously just hypothetical.
Paper Summary
Methodology
Scientists created a system named “Oz” capable of stimulating single photoreceptor cells within the human retina with remarkable accuracy. Initially, they employed adaptive optics optical coherence tomography to categorize approximately 1,000 to 2,000 cone cells in every participant’s retina into types L, M, or S. Subsequently, through adaptive optics scanning laser ophthalmoscopy, they monitored eye movement live via infrared illumination while administering highly focused visible-light laser pulses to particular cone cells. This setup enabled Oz to deliver around 100,000 microscopic doses per second to roughly 1,000 cones inside a 0.9-degree squared area located 4 degrees off the focal point where subjects were looking.
Results
In five separate studies involving 222 color-matching tests conducted with two distinct wavelength stimulations (488 nm and 543 nm), participants encountered a hue referred to as “olo,” which resembled a vivid turquoise-blue shade when the experimenters aimed solely at activating M cones via the Oz system. Further analysis through formal color-matching trials indicated that this particular tint falls outside the typical range of hues perceivable by humans; thus, individuals had to incorporate additional white light to reduce its saturation for comparison against standard shades. Additionally, these same test subjects demonstrated proficiency in identifying imagery and video content depicted in Oz-generated colors, such as crimson outlines and animated spots set against an olo backdrop. However, their accuracy significantly diminished during instances where targeted delivery was intentionally disrupted—by introducing random variations (“jitters”) into adjacent cell activations—which underscored the critical importance of precise targeting techniques.
Limitations
The present system faces notable practical constraints. It functions solely within a narrow 0.9° square visual region located 4 degrees off the participant’s focal point, necessitating that participants keep their gaze steady on a specific target. To enable unrestricted eye movement or to encompass broader visual zones, one would have to chart significantly wider sections of the retina and considerably boost computing capabilities. The contemporary method for identifying cones has advanced to a range within 0.3° of the fovea (the central area of sight), though it still falls short of mapping the tiniest cells right at the core of our vision.
Funding/Disclosures
The study received funding from various sources such as a Hellman Fellowship, an FHL Vive Center Seed Grant, grants from the Air Force Office of Scientific Research, funds from the National Institutes of Health, and a Burroughs Wellcome Fund Career Award. Additionally, the Regents of the University of California submitted a patent application for technology related to cell-by-cell retina stimulation, with many of the involved scientists named as inventors.
Publication Information
The document entitled “New Colors Through Stimulation of Individual Photoreceptors at Population Scale” was released in
Science Advances
On April 18, 2025, the primary contributors to this work are James Fong, Hannah K. Doyle, and Congli Wang, with Ren Ng serving as the corresponding author from the Department of Electrical Engineering & Computer Sciences at the University of California, Berkeley.
