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Color blindness. Daltonisme

5391718_std1Optical illusions can serve a purpose. These images might seem familiar to you. Do they remind you of anything? If you  attended a medical exam at some point in your life, there is a big chance you encountered these during the process. Attached below you may find some examples of color blindness test used for testing if person is partially of fully color blind.

If the you can´t see the numbers clearly, if you have hard time distinguishing the colors apart, or if you aren’t able to easily distinguish at least a vague guess as to what the number is, then you my friend are unfortunately – color blind.

A version of this test can be seen used in the film Little Miss Sunshine, in which a small girl is playing with the vision test chart with her brother. He is not able to see the numbers, or tell the different colors apart well enough to distinguish the numbers. The boy’s goal was to be a pilot, so when he is made aware that he’s colorblind, the poor kid has a small nervous breakdown. As we already stated, color blindness, or color vision deficiency, is the inability to perceive differences between some of the colors that others can distinguish. It is most often of genetic nature, but may also occur because of the eye, nerve, or brain damage, or due to exposure to certain chemicals.


Before we proceed onto our next example, here is a little history lesson: The English chemist John Dalton published the first scientific paper on the subject in 1798, “Extraordinary facts relating to the vision of colors” after the realization of his own color blindness. Because of Dalton’s work, the condition is sometimes called daltonism, although this term is now used for a specific type of color blindness, called deuteranopia. Below you may see the example how one that is colorblind can’t distinguish the numbers on the card. Don’t be mistaken, color blind people don’t see everything in black and white, I just gave this as a guideline so you can understand their inability.


Color blindness is not the swapping of colors in the observer’s eyes. Grass is never red, and stop signs are never green. The color impaired do not learn to call red “green” and vice versa. However, dichromats often confuse red and green items. For example, they may find it difficult to distinguish a Braeburn from a Granny Smith and in some cases, the red and green of a traffic light without other clues (e.g., shape or location). This is demonstrated in this simulation of the two types of apple as viewed by a trichromat or by a dichromat.

apples11

In certain situations, color blindness is classed as a disability. However, color blind people have some advantages over people with normal color vision as well! There are some studies which conclude that color blind individuals are better at penetrating certain camouflages.

On your left, you may see another color vision test card. This one is pretty hard, as some individuals with perfect vision may have problems seeing the number inside it – it is 56 if I’m not mistaken.

Hope we learned something useful today. Before I conclude this article, there are some more vision test examples for you to enjoy:

testcolo1

Looking through the building

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Could you look trought the building or is only an optical illusion?