What is Tetrachromacy? & Why it Matters?
A typical vision human can see millions of colors but in case of people with tetrachromacy this is amplified 100 fold giving a far more vivid and surreal experience of world of colors that is unknown to others.
What is Tetrachromacy?
Tetrachromacy is a rare genetic mutation that causes people with this mutation or tetrachromats to see 100 times more colors than trichromats, people with typical vision. As a result of this mutation tetrachromats have 4 cones or photoreceptors and typical human has 3 cones or photoreceptors, these are responsible for us to see colors.
Tetrachromacy Vs Normal Vision / Trichromacy?
To understand tetrachromacy we need to fist understand trichromacy in detail. A typical human being has three cones in the retina that allow us to see these plethora of colors on the visible spectrum or as we call it VIBGYOR. Each cone allows us to see colors at different wavelengths:
S (Short) Cones: To see colors at short wavelenths like Violet and Blue
M (Medium) Cones: To see medium wavelenth colors like Green and Yellow
L (Long) Cones: To see long wavelenth colors like Orange and Red.
In the case of tetrachromats, they have 4 cones with photopigments and this extra cone with photopigment lets them see many more millions of color variations within the spectrum and opens them up to a world of colors not seen to others.
What causes Tetrachromacy?
An X linked genetic mutation causes tetrachromacy and as it is X linked this rare mutation is seen more in women than men. About 12% or more women are thought to be tetrachromatic with less than 8% of men having the same. The exact numbers on people with this mutation is unknown as there is no easy test for tetrachromacy and even the degree of tetrachromacy varies person to person based on the level of mutation and how your brain perceives the information from the 4th cone so you may have tetrachromacy (4 cones) but not be a true tetrochromat (see all the vivid colors accessible by 4th cone).
How is Tetrachromacy tested?
The most reliable way is to do a complete DNA testing to confirm mutations on the gene responsible tetrachromacy on the X chromosome. Based on the results scientists get closer to understanding if you are a true tetrachromat as just DNA testing may not be enough, there needs to be series of manual testings using different color matching techniques in places designed to do these tests under ideal light conditions to thoroughly understand if your 4th cone photopigment sees all those other colors that typical people can't.
The way an individual perceives color is subjective as it is only know to them and variations occur to an extent. In case of weak tetrachromats, they may still see more colors than typical people but may not see as many and as vividly as a true tetrochromat does.
Several online tests claim accuracy in finding if you are a tetrachromat but none are legitimate as most if not all commercially available screens/devices are designed to show colors perceived by the 3 cones, they display content in trichromatic spectrum and don't have the technology to support the 4th dimension of color or in other words it is not built to be tetrachromatic.