The way we perceive light depends on photoreceptors in our retinas called rods and cones. Specifically, cones help us with our perception of colors. Typical humans and even primates are trichromatic and have 3 types of these cones, but some evidence exists of humans with a sort of “super vision”. A study from 2010 actually suggests that a rare condition known as tetrachromacy exists in up to 12% of women in the world. Tetrachromacy is a condition that describes people who have 4 different types of cones (color receptors).This trait is more likely to be possessed by women than men because of genetics and men are actually more likely to either be color blind or perceive less color. This condition is an X-chromosome linked mutation that only occurs in women due to X-chromosome inactivation. Though the study suggests that there is little evidence to support the idea of tetrachromacy, individuals who carry this mutation cause them to have 4 types of cones.
As stated previously, typical humans have 3 types of cones that perceive wavelengths of light: red, green, and blue or long, medium, and short. However, this 4th cones that exists in some people is thought to give us a better perception and to see the visible light spectrum in more detail. Trichromats are able to differentiate between about 1 million colors, but tetrachromats are thought to be able to differentiate between 100 million colors. In comparison, most people with trichromacy see color in more detail than dogs who are only dichromatic. The photo below illustrates that difference:
The clear difference between typical human and dog vision outlines the potential different in color clarity between trichromacy and tetrachromacy.
But how do we know tetrachromacy even exists?
The most straight forward way to find out if you’re an individual with tetrachromacy is to get genetic testing that could find mutations in the genes relating to the development of cones. However, that doesn’t REALLY tell us the result of those mutations.
The easiest test to see if individuals can actually differentiate between more colors, is simply testing that. Test takers will be given two colors and asked to rate how similar they are on a scale 1-10. When given the card multiple times, they should get the same or similar rating in similarity if one can truly differentiate between the colors.
Further, these test should only be administered by professionals. Online tests to figure out if you’re a tetrachromat are unreliable due to the limitations of computer screens. If you are truly interested in your possibility of being a tetrachromat, you should take part in a legitimate study.