Mothers and Daughters of Colour Blind Men

A tetrachromat is a woman who can see one hundred million colours. That is 99 million more colours than the rest of us can see. The woman will always be the mother or the daughter of a colour blind man. Here’s why.

Most of us have three types of cones in our eyes, each triggered by different wavelengths of light. Each cone gives us the ability to recognize approximately 100 tones (pure colour mixed with another colour). 100 cubed is 1 million.

Because we have three cones, we are trichromats. So are birds and some insects. Almost all other mammals, including dogs, are dichromats. They have two cones in their eyes and see approximately 10,000 colours.

Finding a Tetrachromat

Colour blind men have two normal cones in their eyes plus a mutant cone that is less sensitive to green or red. The mothers and daughters of colour blind men have the mutant cone plus three normal cones.

In 1948, a Dutch scientist by the name of de Vries was testing the vision of two colour blind men. Out of curiosity, he also tested the daughters of one of the men. In his report he made brief mention of ย his suspicion that the females could distinguish more colours than a trichromat.

In the 1980s, neuroscientist John Mollon and his student Gabriele Jordan were studying colour vision in monkeys and they became interested in de Vries little note. They found the mothers of colour blind men and tested them. Zilch. No difference, which is not surprising since it is estimated that only 2-3% of the world’s females may be tetrachromats.

But scientists are nothing if not persistent. In 2007, Jordan tried again using a new test. She showed twenty-five women three coloured circles. Twenty-four of the women considered all three circles to be the same. One woman, however, noted a difference in one of the circles–a circle that was not a pure colour, but was a mixture of red and green that had been randomly generated by a computer. Jordan had her tetrachromat.

Colour is a basic human need…like fire and water, a raw material, indispensable to human life.

Fernand Lรฉger

Would You Know if You Were a Tetrachromat?

Jordan’s subject is an unnamed doctor in England. There’s another tetrachromat in San Diego, an Australian visual artist by the name of Concetta Antico. Antico has become famous because, as an artist, she is able to at least attempt to describe what the world looks like to her. For example, she describes what we see as grey pebbles as “little stones jump(ing) out at me with oranges, yellow, greens, blues and pinks.”

It is fascinating to imagine the world of a tetrachromat. How incredible it would be if each colour that you saw fractured into one hundred more colours.

But if you actually were a tetrachromat, you would face three problems that the rest of us don’t have to contend with.

  1. If you aren’t tested, you won’t ever know you are a tetrachromat because you have no way of knowing that you see more colour than the rest of us.

    You have your brush, you have your colours, you paint the paradise, then in you go.

    Nikos Kazantizakis
  2. Perception of colour comes not from the cones but from the brain’s interpretation of the messages sent by the cones. The natural world may not have enough colour in it for the brain to learn to use a fourth cone.
  3. Being able to see all of those colours is both blessing and curse. Antico describes visits to the grocery store as a nightmare, saying “It’s like a trash pile of colour coming in at every angle.”

Colour and You

You are probably not a tetrachromat, but apparently the more you learn about colour, the more you see variations in it. For a playful, completely non-scientific test of your colour perception, click here.

And if you really want a boost of colour, Antico encourages you to buy her art. She says that in the work of a tetrachromat artist you will feel that the art is alive and vibrant, speaking to you in a way that other art, more devoid of colour, cannot.


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  1. What a fascinating article Karen! I took the color eye test from the link and got a score of 30. Here is what the test said at the end.

    Your color vision and survival skills are incredible. You can recognize a mosquito from miles away.

    This may be because of my fondness for art and color; I am able to look for and pick out variations in color. The color test was interesting to take and gave me a hugely different result than a vision test at the eye doctor’s would have. There I am given a prescription for Tri-Focals. LOL

    Thanks for an interesting and informative post. =)

    1. LOL ah, but swatting said mosquito would be even better. ๐Ÿ˜‰ Being an eagle eye is a great result as well since that is toward the upper end of the scale. ๐Ÿ™‚ It must be all the collages you do that keeps your eyes trained to recognize variants in the color palette.

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