Your eyes have components called rods and cones that help you see light and colors. They’re located inside the retina, the layer of thin tissue at the back of your eyeball near your optic nerve.

Rods and cones are used for sight. Rods allow you to see in the dark. Cones are the main source of color vision.

Most people, as well as other primates like gorillas, orangutans, and chimpanzees (and even some marsupials), only see color through three different types of cones. This color visualization system is known as trichromacy (“three colors”).

There are people who have different color perception channels. This is called a quadrangle of genes.

Tetrachromacy is thought to be rare among human beings. Research has shown that it’s more common in women than in men. A 2010 study suggested that nearly 12 percent of women may have this fourth color perception channel.

Men aren’t as likely to be tetrachromats. They’re actually more likely to be colorblind, or unable to perceive as many colors as women. This is due to inherited abnormalities in their cones.

We will learn more about how to find out if you have it, and what causes it.

The typical person has three types of cones in their eye that allow them to see different colors.

  • Short-wave (S) cones: sensitive to colors with short wavelengths, such as purple and blue
  • Middle-wave (M) cones: sensitive to colors with medium wavelengths, such as yellow and green
  • Long-wave (L) cones: sensitive to colors with long wavelengths, such as red and orange

The theory of trichromacy is related to this. The ability to see the full spectrum of color is given by the three types of cones.

opsin and a molecule that is sensitive to light are the two main components of photopigments. The molecule is called 11-cis retinal. Different types of photopigments react to certain color wavelength that they are sensitive to, which results in your ability to perceive those colors.

Tetrachromats have a fourth type of cone featuring a photopigment that allows perception of more colors that aren’t on the typically visible spectrum. The spectrum is better known as ROY G. BIV (Red, Orange, Yellow, Green, Blue, Indigo, and Violet).

A tetrachromat may be able to see more detail or variety in the visible spectrum. The theory of tetrachromacy is called it.

While trichromats can see about 1 million colors, tetrachromats may be able to see an incredible 100 million colors, according to Jay Neitz, PhD, an ophthalmology professor at the University of Washington, who has studied color vision extensively.

Here is how your color perception works.

  1. The light from your eye is reflected off the retina. The colored part of your eye is the opening.
  2. Light and color travel through the lens of your eye and become part of a focused image projected onto the retina.
  3. Cones tell you the color of light and light color.
  4. The signals are sent to the brain and processed into a mental awareness of what you are seeing.

The human has three different types of cones that divide up visual color information into red, green, and blue signals. The signals can be combined in the brain to make a visual message.

The tegulls have a cone that allows them to see a fourth degree of color. It is a genetic variation.

There is a good genetic reason why women are more likely to be tetrachromats. The possibility of a tri-chromacy is only passed through the X chromosomes.

Women get one X chromosomes from their mother and another from their father. They are more likely to inherit the necessary genes.

“Men only have one X chromosomes. Their genes result in trichromacy or color blindness. The M and L cones don’t see the right colors.”

A mother or daughter of someone with anomalous trichromacy is most likely to be a tetrachromat. One of her X chromosomes may carry normal M and L genes. The other likely carries regular L genes as well as mutated L gene passed through a father or son with anomalous trichromacy.

One of her two X chromosomes will be expressed in some cone cells, while the other X chromosome will be expressed in others. This results in a retinal mosaic composed of four different cone types, because of the variety of different X genes passed on from both mother and father.

“Humans don’t need to be part of the same sex for any evolutionary purpose. They have almost lost the ability. In other species, survival is the main focus.”

Several bird species, such as the zebra finch, need tetrachromacy to find food or choose a mate. And the mutual pollination relationship between certain insects and flowers has caused plants to develop more complex colors.

This has caused insects to see these colors. They know which plants to choose.

“It may be difficult to know if you are a tetrachromat if you have never been tested. You may take your ability to see extra colors for granted because you don’t have another visual system to compare yours to.”

Genetics can be used to find out your status. A full profile of your personal genome can show you the genes that may have caused your fourth cones. A genetic test can show you the genes that were passed on to you.

How do you know if you can distinguish the extra colors from the extra cone?

That is where research can be useful. There are many ways to find out if you are a tetrachromat.

The color matching test is the most important test. It goes like this in a research study.

  1. The study participants are presented with a set of two colors that are different to each other.
  2. The participants rate the similarity of the mixtures.
  3. The participants are given the same sets of color combinations at a different time, but not told if they are the same combinations or not.

The colors will be rated the same way every time, meaning that they can actually differentiate between the two pairs.

The trichromats choose random numbers when they rate the same color mixtures.

Warning about online tests

Note that any online tests that claim to be able to identify tetrachromacy should be approached with extreme skepticism. According to Newcastle University researchers, the limitations of displaying color on computer screens make online testing impossible.

Sometimes tsarchromats make big media waves.

A participant in the 2010 Journal of Vision study, known only as cDa29, had perfect tetrachromatic vision. She made no errors in her color matching tests, and her responses were incredibly quick.

She’s the first person to have been proven by science to have tetrachromacy. Her story was later picked up by numerous science media outlets, such as Discover magazine.

In 2014, artist and tetrachromat Concetta Antico shared her art and her experiences with the BBC. In her own words, tetrachromacy allows her to see, for example, “dull grey … [as] oranges, yellows, greens, blues, and pinks.”

The stories show how much this rarity still interests those of us who have a three-cone vision.