Tetrachromacy, or having four types of cone cells in your eyes, is a rare condition that allows some people to see many more colors than the average person. While most humans are trichromats and have three types of cone cells that allow them to see red, green and blue light, tetrachromats have an additional fourth type of cone cell that is sensitive to another wavelength of light. This allows them to perceive up to 100 million more shades of colors that are invisible to the rest of us! Tetrachromacy is a fascinating genetic mutation that only affects a small percentage of the population, predominantly women. If you suspect you may be a tetrachromat, there are a few different tests you can try at home to find out.
The Genetics Behind Tetrachromacy
Tetrachromacy is linked to two X chromosomes. To be a tetrachromat, you must have two different versions of the red and green photopigment genes on each X chromosome. One version codes for longer wavelength or red sensitive pigment, while the other codes for medium or green wavelength pigment. Having different variants of these genes on each X chromosome provides more spectral coverage and allows you to have four types of cone cells. This XY sex chromosome combination happens more frequently in women, who have two X chromosomes. Men only have one X chromosome, making tetrachromacy extremely rare.
Online Color Vision Tests
One of the easiest ways to test for tetrachromacy is by taking an online color vision test. There are several good options that present you with colorful dot tests and spectral bands to distinguish subtle shades and wavelengths that are indistinguishable to most people. The online tests will compare your results to the average trichromat and let you know if your color perception falls outside the normal range. Two well-known online color vision tests to try are:
- X-Rite Color Challenge
- Tetrachromacy Test
These online challenge tests take about 5 minutes and will analyze your color discrimination abilities. If you can see certain hues and distinguish subtle spectral differences that most can’t, it may indicate you have tetrachromatic powers!
The FM100 Hue Test
The FM100 Hue Test is a more advanced clinical color vision test that can accurately identify tetrachromatic vision. It consists of 93 color caps with indiscriminable hue that are arranged to form a circle. You simply have to put the caps in order based on the spectral wavelength and hue you perceive. The caps have increments as small as 1 nanometer that are imperceptible to most people. But a tetrachromat would be able to distinguish the minute differences. The test results are quantified with a score, and only tetrachromats are able to attain a perfect score of zero on this exceptionally difficult test. Unfortunately, the FM100 Hue Test equipment is not readily available to consumers and can only be administered by vision scientists. But reaching out to university researchers may make taking the test possible if you strongly suspect tetrachromacy.
Genetic Testing
The most definitive way to confirm if you are genetically a tetrachromat is through genetic testing. A DNA test can identify if you have genetic mutations on both X chromosomes that enable a fourth cone photopigment. There are a few options for genetic testing, including:
- 23andMe ancestry DNA test – Tests for 4 genetic variants linked to tetrachromatic vision
- HumanOptics – Specialized genetic testing for color vision
- Scientific research studies – May offer free genetic testing for research volunteers
Keep in mind, having the right genetic makeup does not guarantee you are functionally a tetrachromat. The additional cone cells must be integrated properly into your retina and visual cortex to allow enhanced perceptual abilities. But genetic testing can conclusively prove if you have the potential for tetrachromatic vision based on your DNA.
Real World Observation
Living as a tetrachromat means you see the world differently every day. Keeping an eye out for instances where you can observe more shades, hues and color nuances in real world scenes may provide clues to your abilities. Notice if you see many more gradients, textures and details in things like:
- Sunrises and sunsets
- Rainbows
- Autumn foliage
- Flower arrangements
- Subtle skin tones and eye colors
Pay attention when looking at complex spectra like rainbows – a tetrachromat might see more delineated bands of color than a trichromat. Or notice if you think a painting has many more distinct pigments than others can identify. If your daily visual perception seems richer in color, it could signal tetrachromacy.
Specialized Equipment
There are advanced tools and equipment eye doctors and vision scientists can use to test for tetrachromacy that are not available to the average consumer. These include:
- Retinal imaging – Takes high resolution images of cone photoreceptors
- Electroretinography – Measures electrical response of photoreceptors
- DNA Microarray – Explores genetic basis of color vision
- Anomaloscope – Mixes spectral lights in different ratios
Making an appointment with a behaviorial optometrist or vision research team at a university may make it possible for you to access these technologies. They allow physiological confirmation of a fourth cone type in your eyes, which is the most reliable proof of tetrachromatic abilities.
Conclusion
Tetrachromats have a rare gift of extraordinary color perception thanks to their unique genetic makeup. If you suspect you may have tetrachromatic vision, taking an online color test is a good first step to gauging your abilities. Consider genetic testing to look for tetrachromacy linked gene variants. And document any real world observations of your enhanced color experiences. Accessing advanced clinical tests and imaging remains the holy grail for confirming tetrachromacy, so reach out to vision experts if needed. With the right evidence, you can prove your superpowered tetrachromat status!