The Discovery of the New Colour Olo and What it Reveals About Perception
Estimated reading time: 11 minutes
Scientists at the University of California, Berkeley, have recently discovered a new colour named olo. It cannot be seen in nature, yet it is reported as more vivid than any colour ever seen by humans. This has sparked both excitement and controversy. Why does this research matter? Can a colour created in a lab, and invisible to the naked eye be considered a real colour? What even is a colour? And what does olo teach us about how our brains construct reality?
Some say olo blurs the distinction between reality and perception. I believe it sharpens it. Keep reading.
What exactly is olo?
Olo is a colour that can only be seen when induced by laser light under very specific conditions. It has been described as a peacock blue or teal more vibrant than anything found in nature (Manke, 2025). The colour was discovered by a team led by Professors Austin Roorda and Ren Ng at the University of California, Berkeley, in collaboration with researchers from the University of Washington. Their goal was to explore whether the human brain could perceive a completely new colour by stimulating just one type of light-sensitive cell in the eye, specifically, the M cones. Using advanced optics and precise laser targeting, they isolated these cells and found that this produced a perceptual experience that people had never had before: a new colour, now known as olo.
Who has seen it and what did they see?
At the time the paper was published, only five people, all with normal colour vision, had seen olo. One of them, Professor Roorda, described the experience as seeing “a profoundly saturated teal… the most saturated natural color was just pale by comparison” (Fong, 2025). Others described it as “an intensely saturated teal” and “a blue-green of unmatched saturation.”
It is worth noting that participants did not see olo across their entire visual field. Instead, it appeared as a small patch in the periphery. This is because the cones in the centre of the visual field (the fovea) are too tightly packed for precise stimulation. Peripheral cones, however, are more spaced out, allowing the laser to isolate them more reliably. The perception of olo lasted only as long as the cones were being stimulated.
How do we know what colour they saw?
The participants were asked to match the colour they perceived using two methods: by tuning a laser wavelength and by adjusting free-wheeling dials on an RGB projector to modify the hue, saturation and brightness. Both systems also had a further dial to add white light. The participants stated that olo did not match the vividness of any known colour and its intensity and richness were such that they needed to “wash out” the colour with a significant amount of white light to approximate a known colour. The resulting match resembled a blue-green that sits outside the colour range displayable by standard means.
Here is a fun challenge: if you had to describe a colour no one else had ever seen, how would you start? It is harder than it sounds. Give it a go and share in the comments.
How was olo created?
The Oz device uses extremely precise imaging technology that allows researchers to identify and track specific cells in the retina. The research team mapped the locations of the different cones (light-sensitive cells) in the retina for each participant and then used microscopic doses of laser light, targeted at specific cone types. This method enables them to study how individual cones contribute to perception. The laser stimulation creates a visual perception that the researchers call an “Oz percept.” To produce the percept of the new colour olo, they targeted the laser exclusively at the M cones.
What are these cones, you ask? Glad you did.
How does the brain create colours?
This part digs deeper into how colour vision works. Feel free to skip ahead if this is not your thing.
Physiologically, colour is the perceptual experience that results from our eyes experiencing different wavelengths of light. Cones are the photoreceptors in the back of the eye involved in picking up this information. The actual experience of colour happens further into the brain and it is the result of neuronal processes across different parts of the brain.
1) Light is detected by the cones in the retina
When light enters the eye, it is absorbed by photoreceptors in the retina that convert energy to electrical impulses. The photoreceptors that are sensitive to different wavelengths of light are the cones. Typically, humans have 3 cone types (S, M and L), each containing photopigments (opsins) that are maximally sensitive to different wavelengths: short (S, blue), medium (M, green) and long (L, red) (see chart below). Assigning colours to the wavelengths is an oversimplification, but it will do for now. As the chart shows, there is a certain overlap in the wavelength sensitivity of each cone. This is crucial for colour perception, as it means that no naturally occurring wavelength stimulates only one cone type. For example, light at 550 nanometres (nm) activates L cones, but it activates M cones more strongly.
2) Further neural processing happens in the visual cortex.
This colour information travels down the optic nerve towards the visual cortex, where it is processed by comparing the relative activation of all three cone types, rather than interpreting the signal from any cone in isolation. All the colours that we perceive result from the computation of input from these three cone types. “Is there no yellow cone?” you ask. We do not need a yellow cone. A wavelength of about 570-590 nm would stimulate both M and L cones. The brain interprets high L + M activation as yellow. By the way, the 550 nm mentioned earlier is perceived as yellow-green, or “chartreuse” if you are familiar with design colour charts… or liqueurs.
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Clarification: “maximally sensitive” means that cones respond to a range of wavelengths but respond more strongly to a particular one. For example, the S cone responds maximally at 420 nm, and half as strongly at 400 nm and at 440 nm. Because different combinations of wavelengths can produce the same pattern of cone activation, we can perceive the same colour from physically different light sources, these are called metamers. But I digress.
What makes olo so special?
Researchers used light with a wavelength of 543 nm to evoke olo. This wavelength was chosen because it strongly stimulates M cones while minimising activation of S cones, and it is a standard, reliable laser wavelength commonly used in vision research. Under natural conditions, 543 nm light typically appears green. Due to the overlapping sensitivity of the three cone types, any light we encounter usually stimulates more than one cone type. In this case, 543 nm light primarily activates M cones (which peak around 530 nm), but also stimulates L cones (peaking around 560 nm) to a lesser degree and may slightly stimulate S cones (peaking around 420 nm), if at all.
What makes olo fundamentally different, and the reason it cannot be seen outside a lab setting, is that researchers targeted the 543 nm laser light exclusively to hit M cones, bypassing both S and L cones. This precise, isolated stimulation led to the unprecedented perceptual experience of olo: a colour literally never seen before.
Why the name olo?
The name olo was coined to reflect the binary code 010, representing the input for each cone type: 0 (S cone), 1 (M cone) and 0 (L cone).
Same wavelength, many colours.
Here’s a twist: the same 543 nm wavelength that evoked olo also induced other colours. The team experimented targeting different cone types and configurations while keeping the wavelength constant to examine how this isolated stimulation affects the colour perceived. As a result, participants reported seeing orange, yellow, green, and blue-green. As the authors note, “the appearance of light depends strongly on the identity of the cone targeted,” even when the physical stimulus remains the same. This highlights the importance of the spectral sensitivity overlap of L, M, and S cones and demonstrates that colour perception arises from comparative processing across cone types.
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Reception of the news and debates
The discovery of a new colour doesn’t happen often. Naturally, olo has sparked interest, raised questions, and unsettled a few assumptions. But beyond the novelty, what does this research actually show us? And what does it help reveal about how we perceive and make sense of the world?
Is olo really a colour if most people cannot see it?
Even among humans, colour is not a fixed experience, meaning that the same wavelength can evoke different colour perceptions from person to person. A common genetic variation makes some women tetrachromats, giving them a fourth cone and allowing them to see an entire range of colours that are invisible to most. But the colours they see are as real as those we all see. The existence of a colour does not depend on how many people can see it, but on whether it reliably produces a consistent and specific neural response.
Some argue that since olo cannot be seen in nature, it is not a real colour. However, olo meets the definition of colour: it is a phenomenological experience that arises when the brain processes light information received by the photoreceptors (albeit via a laser). I disagree that it cannot be experienced naturally; the stimulation is artificial, but the perception is as real as with any colour and is produced by the same neural mechanisms.
Is olo a novel colour?
The researchers claim that this is a new colour, as it remains outside of the usual gamut. Some experts argue that olo falls within the blue-green spectrum, and therefore it does not truly constitute a novel hue but rather an extreme variation of existing hues. A challenge is that describing a colour to people who have never experienced it inevitably relies on comparisons to the colours they already know, making it difficult to determine if olo is truly distinct.
Is the sample size too small?
Some media commentary and online discussions, particularly on platforms like Reddit, have questioned the small number of participants in the olo study. With only five people taking part, it is reasonable to ask: is that enough?
Yes, it is. This research was not designed to define a new colour but rather to serve as a proof of concept, to test whether a novel perceptual experience could be induced at all through precise, cone-specific stimulation. This type of research requires intensive preparation, including high-resolution retinal mapping for each participant and multiple sessions of cone stimulation and colour matching. The focus is on collecting rich, highly controlled data from each individual, and for this, a small sample size is standard practice and is scientifically appropriate.
Why is this research significant?
One of the central challenges in neuroscience is isolating variables tightly enough to draw clear conclusions. What makes this study remarkable is that researchers were able to do just that: stimulate specific cone types directly and produce a precise, repeatable percept.
This was not the first time the Oz technology was used, but it was the first time it stimulated a large enough number of cones to generate a full perceptual experience. As the authors write, "These results are proof-of-principle for programmable control over individual photoreceptors at population scale” (Fong et al., 2025).
Olo confirms that colour is a neural event. Light is only the source, but our experience of colour is shaped by our neural architecture.
That said, our perceptual experience also physically shapes our brain, but that is a topic for another day.
What could this mean for the future?
The precision of the Oz system opens up new ways to study the visual system at an unprecedented scale and with a degree of control not available before. It allows researchers to explore how the brain integrates new visual inputs. Crucially, it can simulate the effects of adding new cone types in a completely non-invasive way. This includes the potential to restore colour perception in colourblind individuals, and even to induce forms of tetrachromacy, allowing humans to experience a broader and previously inaccessible range of colours. Researchers are also exploring how Oz could be used to simulate cone loss in healthy individuals, allowing them to model and study visual disorders caused by cone deficiencies.
Final thoughts: what olo teaches us about reality
Olo is described as a colour more vivid than any found in nature, yet it cannot be made into a pigment or seen without being induced. Some argue this blurs the boundary between perception and reality. I believe differently, I think olo sharpens this distinction. The fact that olo can be induced through artificial stimulation of our sensory system emphasises that colour exists as a neural event. In this sense, olo does not challenge our understanding of reality; it underscores that what we perceive as “real” is a construct of our unique neural architecture.
If this post made you think differently about colour or perception, you will probably enjoy what is coming next. I will be writing more about vision, sensory illusions, case studies and all things brain.
Have thoughts, questions, or something to add? Drop a comment below. Science, like art, is a conversation.
References
Fong, J., Doyle, H. K., Wang, C., Boehm, A. E., Herbeck, S. R., Pandiyan, V. P., Schmidt, B. P., Tiruveedhula, P., Vanston, J. E., Tuten, W. S., Sabesan, R., Roorda, A., & Ng, R. (2025). Novel color via stimulation of individual photoreceptors at population scale. Science Advances, 11(16), eadu1052. https://doi.org/10.1126/sciadv.adu1052
Lanese, N. (2025, April 18). Scientists hijacked the human eye to get it to see a brand-new color. It's called 'olo.' Live Science. https://www.livescience.com/health/neuroscience/scientists-hijacked-the-human-eye-to-get-it-to-see-a-brand-new-color-its-called-olo
Manke, K. (2025, April 22). Scientists trick the eye into seeing new color ‘olo’. Berkeley News. https://news.berkeley.edu/2025/04/22/scientists-trick-the-eye-into-seeing-new-color-olo/
Muy interesante y claro, gracias por compartir esta información