Tetrachromacy is a rare condition where someone has four types of cone cells in their eyes, allowing them to see many more colors than most people. While researchers estimate tetrachromats make up less than 1% of the world’s population, it’s possible you could be one without even knowing it. Here’s what tetrachromacy is, how to tell if you might have it, and what life is like for tetrachromats.
What is Tetrachromacy?
Most people are trichromats, meaning they have three types of cone cells in their eyes that allow them to see color. The three cone cells detect light from the red, green, and blue parts of the visible light spectrum. The cones have different levels of sensitivity to wavelengths of light, which our brain processes into all the colors we perceive.
Tetrachromats, on the other hand, have four cone cell types instead of three. Their eyes contain cones sensitive to red, green, blue, and yellow wavelengths. This extra dimension in color vision allows tetrachromats to experience a world of color most of us can barely imagine.
How Many Colors Can Tetrachromats See?
Scientists estimate trichromats can perceive up to 1 million different colors. For tetrachromats, that number soars to 100 million or more possible colors. Such a staggering difference comes from the extra type of cone cell.
For example, trichromats see different hues of red, green, and blue, along with combinations between them. But they can’t distinguish subtle variations in yellows the way tetrachromats can. The added sensitivity to yellow wavelengths opens up the yellow-blue color axis, exponentially increasing the variety of colors tetrachromats may experience.
Tetrachromat Vision Spectrum
This diagram compares the vision spectrum of trichromats and tetrachromats:
| Trichromat Vision | Tetrachromat Vision |
|---|---|
| Sensitive to red, green, and blue wavelengths | Sensitive to red, green, blue, and yellow wavelengths |
| Sees up to 1 million colors | Potentially sees up to 100 million colors |
As you can see, the additional yellow cone sensitivity adds a whole new dimension of color for tetrachromats.
Tetrachromat Test
Researchers use specialized vision tests to identify tetrachromats. These tests evaluate how sensitive someone’s eyes are to colors of various wavelengths. They help determine if the test subject has four cone cell types instead of the normal three.
Online tetrachromat tests you can take evaluate color perception in a more basic way. For example, they may show subtle color gradient shifts and ask you to identify when the colors change. The ability to notice very slight differences, especially in yellow hues, may indicate tetrachromatic powers.
However, online tests aren’t definitive proof of tetrachromacy on their own. Extensive lab testing is required to confirm tetrachromatic vision conclusively. Still, online tests can suggest it’s worth looking into tetrachromacy further if you get very high scores.
Do Tetrachromats See New Colors?
Sometimes tetrachromacy is misunderstood to mean those with the condition can see colors no one else can see. In reality, they see expanded variations of colors on the normal visible spectrum. They can distinguish extremely subtle differences between colors most people would say look exactly the same.
For example, trichromats may see five slightly different shades of yellow as all being the same yellow color. But a tetrachromat might see each of those five yellows as distinct colors. Their yellow sensitivity doesn’t let them see infrared or ultraviolet light like some animals can. But it does allow them to experience familiar colors on a level unattainable for trichromats.
Famous Tetrachromats
Very few scientifically confirmed tetrachromats are known, given the condition’s rarity. Some potential candidates include:
- Concetta Antico – Artist who claims enhanced color perception
- Cynthia McDonald – San Diego teacher identified as a tetrachromat in studies
- Caitlyn Jenner – Reported being a tetrachromat during Keeping Up with the Kardashians
However, only Concetta Antico has publicly released results confirming her tetrachromatic abilities. The condition likely remains undiscovered in many others who don’t realize their vision is extraordinary.
Possible Benefits of Tetrachromacy
What’s it like existing in a world of such vivid color? Tetrachromats describe colors as appearing more intensely saturated compared to trichromatic vision. Reds may seem redder, greens greener, and so on across the spectrum.
Possible benefits of being a tetrachromat include:
- Richer, more enjoyable color experiences
- Enhanced ability to discern subtle color differences
- Advantages in color-related fields like graphic design or painting
- Increased color perception in low light conditions
Artists with tetrachromacy may have techniques and creative visions simply impossible for most colorblind trichromats.
Drawbacks of Tetrachromacy
There are also some possible downsides of having four cone cell types:
- Overstimulation from extremely vivid colors
- Frustration with inability to share full color experience
- Misperceiving certain colors due to added sensitivity
- Errors identifying colors others see as the same
Some tetrachromats may feel constant sensory overload from the hyper-saturated world they live in. What seems beautiful and vibrant to them may appear gaudy or excessive to trichromats – and vice versa.
Rarity of Tetrachromacy
Only a small fraction of the population possesses the genes for tetrachromacy. Researchers estimate 1-2% of people, mainly women, potentially have tetrachromatic vision. However, even fewer know they’re tetrachromats since specialized testing is required to confirm it.
For someone to be a tetrachromat, they must inherit two different genes for the red and green cone cells. Trichromat men only have one X chromosome, making tetrachromacy impossible for them.
Women have two X chromosomes, so they can inherit both a gene for normal red cone sensitivity and an extra gene for enhanced green sensitivity. This provides the potential for four active cone cell types instead of the usual three that lead to trichromatic color vision.
Genetics of Tetrachromacy
| Vision Type | Cone Cell Genes |
|---|---|
| Trichromat | 2 normal red and green genes |
| Tetrachromat | 1 normal + 1 mutant red or green gene |
As you can see, two normal red and green cone genes lead to trichromatic vision. But when someone inherits one normal and one mutant variant of either the red or green gene, it can enable tetrachromacy.
Prevalence in Animals
Tetrachromatic vision occurs in many animal species as well. Birds, fish, amphibians, reptiles, and insects often see four or more primary colors. Their enhanced color perception can provide advantages finding food, avoiding predators, and other survival benefits.
Examples of tetrachromatic animals include:
- Birds
- Reptiles
- Amphibians
- Fish
- Insects
- Spiders
- Shrimp
Humans evolved with three cone types, which suffices for most color discriminations needed in our ancestrial environment. But other species clearly benefited from even broader color vision through tetrachromacy’s four or more cone cell types.
Research History
The potential for tetrachromatic vision in humans was hypothesized in 1948 by Dutch researcher H.L. de Vries. But it remained theoretical for decades after.
In the 1980s, John Mollon at Cambridge University took interest in the idea. He suspected the women in his lab with keen color perception might be tetrachromats. But technology to verify it experimentally still didn’t exist.
The first potential tetrachromat was identified in 1993 by researchers at Newcastle University. Gabriele Jordan was found to possess enhanced color vision after undergoing extensive lab testing.
Since then, scientists have used new technology to study and validate other tetrachromats like Concetta Antico. But research into human tetrachromacy remains an emerging field with most discoveries still to come.
Conclusion
Tetrachromacy is an intriguing and extremely rare variation in human color vision. If you suspect you may have extraordinary color perception, specialized tests are needed to check for the signs of being a tetrachromat. There are only a handful of confirmed tetrachromats known so far. But researchers believe many more likely have the condition while being unaware of their special talents.
Advancements in genetics and vision testing technology will help uncover more tetrachromats in the coming years. That will provide fascinating opportunities to understand how they experience the world compared to the rest of us trichromats. Unlocking the secrets of tetrachromatic vision could have major implications in diverse fields from neuroscience to art.
