Tetrachromacy in Humans: All You Need To Know

Imagine being able to see millions more colors than the average person!

For a rare group of individuals, this isn’t just imagination but reality. This extraordinary ability, known as tetrachromacy, equips them with a fourth type of cone cell in the eye. This enables vision so rich that an ordinary rainbow looks incomplete by comparison.

Scientists estimate that while most people see about one million shades, tetrachromats may perceive up to 100 million. Yet many who have this gift don’t even realize it because their world of expanded colour seems perfectly normal to them.

Let’s delve into this article to learn the causes of this phenomenon, how it was discovered, how it works and if you could unknowingly be one of the few people with superman color vision.

Introduction to Human Color Vision

Human color vision is a remarkable feature of the visual system, allowing you to distinguish colors, describe colors, and perceive the same color consistently across different contexts. At its core, this ability relies on the retina, a thin layer at the back of the human eye, which contains specialized cells called cone cells. These cone cells are photoreceptor cells sensitive to light within the visible spectrum, roughly from 380 to 700 nanometers.

Most people, or the average person, experience normal vision through three types of cones: S cones (sensitivity to short wavelengths, like blue), M cones (medium wavelengths, like green), and L cones (long wavelengths, like red and orange).

This trichromatic system processes light signals in the brain, creating the rich palette of colors we see worldwide. A 2017 study on how humans see in vision, estimates that humans can distinguish up to 10 million colors.

However, according to a 2023 study by Scientific American on color in the eye, not everyone sees the world similarly. Variations in cone cells can lead to differences in color perception.

For instance, color blindness, or being color blind often results from missing or altered cone types, making it harder to distinguish colors like red and green. On the other end of the spectrum lies tetrachromacy, a condition where individuals have four cone types, potentially enabling super vision.

What is Tetrachromacy

A 2023 article on Tetrachromacy: Superhuman vision? describes tetrachromacy as the presence of a fourth cone type in the retina, which adds an entirely new dimension to color perception.

Unlike the majority of humans, who rely on three cone types (S, M, and L) to process colors in a three-dimensional color space, tetrachromats operate in a four-dimensional color space. This means they can potentially distinguish shades and hues that appear identical to the rest of us, unlocking a richer and more complex palette of colors.

In humans, tetrachromacy is extremely rare but scientifically fascinating, as it suggests the possibility of what many call “superhuman vision.” While trichromats can differentiate millions of colors, tetrachromats may see variations invisible to the average eye, colors that others cannot even imagine.

This phenomenon has been linked particularly to individuals with a fourth cone type that falls spectrally between the medium-wavelength (M) and long-wavelength (L) cones, giving them heightened sensitivity to subtle wavelength differences, especially in the red-green range.

However, having four cones does not automatically guarantee tetrachromatic vision. For it to truly function, the brain must process these signals separately and independently through advanced post-receptoral mechanisms. In other words, the visual system must not only receive information from four cones but also integrate it in a way that creates unique perceptual experiences beyond those of trichromacy. When this happens, the result is an expanded visual reality where ordinary colors split into extraordinary variations, where a single shade of paint might appear as multiple distinct tones to a tetrachromat.

The possibility of tetrachromacy in humans challenges our understanding of perception itself. It raises intriguing questions: Do tetrachromats experience a world we cannot even describe? Is their “blue” the same as ours, or something completely beyond our comprehension?

While research is still unfolding, tetrachromacy serves as a reminder that what we call “color” is not absolute but deeply tied to the biology of our eyes and the wiring of our brains.

How Normal Color Vision Works: Trichromats vs. Dichromats

In normal trichromatic vision, three types of cone cells (S, M, L) enable humans to mix signals and perceive a wide array of hues. Rods, on the other hand, help us see in dim light and detect shades of black, white and gray.

In trichromats, the brain interprets colors by comparing the signals it receives from these three cones. For example, when you look at a yellow object, both the L-cones and M-cones are strongly stimulated, while the S-cones are less active. The brain processes this combination of inputs and perceives the color yellow. This system allows trichromats to distinguish millions of shades and hues.

In contrast, dichromats have only two functioning types of cone because one cone type is missing or not working properly. As a result, their ability to perceive the full spectrum of colors is limited. Depending on which cones are absent, dichromats may struggle to distinguish between certain colors.

For example, people with protanopia lack L-cones and have difficulty perceiving reds, which often appear darker. Those with deuteranopia lack M-cones and commonly confuse reds and greens. Tritanopia is rare but occurs when S-cones are missing, leading to difficulty distinguishing between blues and yellows.

The main difference is that trichromats experience the full range of normal color vision while dichromats perceive a reduced palette with certain colors appearing muted, altered or easily confused with one another.

Discovery of Tetrachromacy: The Journey Begins

The idea of human tetrachromacy first emerged from genetic research. Scientists discovered that some women, particularly carriers of anomalous trichromacy, might possess the biological foundation for an extra cone type.

Because women have two X chromosomes, each carrying opsin genes that encode photopigments, variations between the two can, through the process of random X-inactivation, lead to the expression of a fourth cone in addition to the usual three. This possibility laid the genetic groundwork for an expanded visual dimension beyond standard trichromacy.

By the 1980s, researchers such as John Mollon began exploring this idea more seriously, proposing that women with such variant opsin genes might indeed harbor additional cone types. This line of inquiry emphasized how genetic differences could open the door to tetrachromatic vision.

In contrast, men, having only one X chromosome, are far less likely to develop this condition, though rare cases remain theoretically possible.

The Role of the Fourth Cone Cell in Tetrachromacy

A fourth cone, typically a variant between M and L cones, would introduce an additional channel for capturing subtle wavelength differences. But for strong tetrachromacy, it’s not enough to have four cone types; the brain must also process them independently, potentially adding a fresh dimension to color processing. Only then can individuals distinguish colors based on four separate inputs instead of three.

In weak tetrachromacy, the extra cone’s signal may be treated as redundant. This extra cone type enhances perception in shades of green, yellow, orange, and even blue, but requires proper neural integration for full benefits.

The Search For Tetrachromats: Early Research and Findings

Early research on tetrachromacy began with genetics. The genes that encode cone pigments are located on the X chromosome, so women who carry two X chromosomes are seen as more likely candidates for tetrachromacy than men who carry only one.

In the 1940s, Dutch scientist H.L. de Vries provided one of the first clues when he observed that some women related to men with red-green colour blindness seemed to have unusually heightened colour perception. This suggested they might carry an extra cone pigment variant. Later studies in the 1980s and 1990s built on this genetic foundation.

Researchers found that a significant percentage of women carried mutations that could in theory give rise to a fourth cone type. However, having the genetic potential did not necessarily mean these women could use the extra cone for richer color perception. It became clear that the brain would also need to process the signals in a way that enabled clearer distinctions between colors.

In 2010, neuroscientist Gabriele Jordan at Newcastle University conducted some of the most notable modern research on the dimension of colour vision. She tested women with the genetic profile for four cone types using extremely subtle color matching experiments. Among her participants, one woman showed clear evidence of tetrachromatic vision. She could reliably distinguish between colour variations that looked identical to trichromats. This provided one of the strongest cases for functional tetrachromacy in humans, though such cases remain rare and difficult to verify.

These early findings suggest that tetrachromacy is not merely theoretical but may exist in a small subset of the population, particularly women with specific genetic variants. However, the exact prevalence and functional significance of tetrachromacy are still under investigation, as much depends not only on genetics but also on how the brain adapts to process visual input.

The 2007 Breakthrough: Identifying the First True Tetrachromat

In 2007, neuroscientist Gabriele Jordan made a landmark discovery when she identified the first strong case of human tetrachromacy. The subject, known as cDa29, showed the ability to see colors that ordinary trichromats could not.

In tests focusing on the 546–670 nanometer range, where the usual S-cones (blue-sensitive) are less effective, she consistently demonstrated a four-dimensional color vision. Through carefully designed experiments using color-matching and forced-choice tasks with specially calibrated instruments, cDa29 outperformed typical participants, providing clear evidence of functional tetrachromacy.

The discovery was groundbreaking. It proved that tetrachromacy in humans was not just a theoretical possibility based on genetics but a functional reality in at least one individual. While millions of women may carry the genetic variations for a fourth cone, very few appear to develop the necessary neural wiring to process this expanded spectrum of colour. The subject cDa29 remains a rare case and a living confirmation that the human visual world may be richer than most people can experience.

Potential Impact: How Tetrachromats Perceive the World

Tetrachromats may perceive colors in ways that appear indistinguishable to the rest of us, unlocking a far more nuanced and complex palette. Where a trichromat might see a single shade of yellow, green, orange, or blue, a tetrachromat could detect multiple subtle variations, each standing out as distinct.

This expanded perception suggests practical advantages in areas where fine color discrimination is critical. For instance, in art and design, tetrachromats could identify and blend shades with exceptional precision. In medical or biological contexts, they might notice minute changes in skin tone, tissue coloration, or diagnostic imagery that others would overlook.

Similarly, in forensics, quality control, or material sciences, heightened color sensitivity could offer a unique edge in detecting mismatches, alterations, or hidden details. Although much of this remains theoretical and supported mainly by anecdotal observations, the possibility of such abilities underscores the broader implication of tetrachromacy: an enriched perceptual world where the familiar spectrum of colors expands into dimensions that most humans will never directly experience.

Why Most Tetrachromats Remain Undiscovered

Most people are unaware of whether they are tetrachromats for several reasons. Online vision tests and computer screens cannot accurately reveal tetrachromatic vision because digital displays are based on RGB systems, which have a limited range of color reproduction. Even when a woman carries the genetic basis for tetrachromacy, she may not have the necessary neural processing to make full use of the extra cone type.

In such cases, the brain often treats the additional cone’s input as redundant, leading to weak or non-functional tetrachromacy. Many potential tetrachromats also remain unaware because they perceive the world in the same way as everyone else, without any baseline for comparison.

For men, the condition is even less likely since they have only one X chromosome, making true functional tetrachromacy especially rare among them.

Ongoing Research: The Future of Color Vision

Contemporary studies focus on the plasticity of the visual system and whether it can adapt to incorporate a fourth channel. Researchers like John and Mollon explore experimental designs, color matching, and multidimensional scaling to detect strong tetrachromacy. Theoretical work expands to engineering applications, such as printing systems that simulate or exploit tetrachromatic color processing. Evolutionary perspectives suggest that tetrachromacy may reflect untapped potential within photopigment gene flexibility, ready to be activated under permissive conditions.

In 2025, groundbreaking advancements include the Oz principle, where lasers stimulate individual cone cells to create novel-like Olo, a hue never seen before by human eyes, expanding our understanding of color perception.

Philosophical inquiries compare tetrachromacy to such innovations, questioning subjective experience. Recent discussions on X highlight student presentations on tetrachromacy, showing growing interest in educational contexts. As current opinions evolve, further research, including from institutions like the Cleveland Clinic, refines methodology for testing.

Conclusion: Seeing the World Through Super Vision

Tetrachromacy in humans is a fascinating frontier in biology, behavioral sciences, and solving the mystery of color perception. It encompasses tetrachromatic vision, superhuman vision, and the intriguing notion that only women, by having two X chromosomes, may nurture this ability, though most remain undiscovered.

Confirming how to test for tetrachromacy involves genetic testing and precise psychophysical experiments, not online quizzes or casual observations. As further research refines methodology, we could one day better understand how people who can see more colors navigate the world, and what it means for our understanding of the human eye, brain, and visual system.

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Frequently Asked Questions

How to tell if you have tetrachromacy?

The only reliable way to confirm tetrachromatic vision is through specialized color discrimination tests conducted in controlled lab settings, often alongside genetic analysis of your opsin genes. Online tests and regular eye exams cannot provide definitive results.

Can only women have tetrachromacy?

Most confirmed human tetrachromats are women due to having two X chromosomes, which increases the chance of carrying an extra opsin gene. However, rare cases in men are theoretically possible but not yet confirmed.

Does tetrachromatic vision improve life?

Yes, beyond artistic or aesthetic advantages, most tetrachromats report subtle differences in matching colors, noticing more shades, and enhanced color perception in nature, art, and design.

How rare is tetrachromacy in humans?

It is extremely rare, estimates suggest that while a small percentage of women may carry the genetic potential, only a tiny fraction have functional tetrachromatic vision that allows them to truly perceive colors beyond the trichromatic range.

How to test for tetrachromacy at home?

While some websites offer online quizzes, home-based or computer screen tests are unreliable. Screen technology cannot reproduce the wavelengths needed to detect superhuman vision.

Sources

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7. Scientists Have Found a Woman Whose Eyes Have a Whole New Type of Colour Receptor
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17. Novel color via stimulation of individual photoreceptors at the population scale
18. Scientists create a new color never before seen by human eyes
19. Scientists hijacked the human eye to get it to see a brand-new color. It’s called ‘olo.’
20. Scientists modified the eyes of 5 humans to see an ‘unprecedented’ new color