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Asked by jammydodger72x to Alexander, Josh, Serena, Simone, Stuart on 17 Jun 2013.
Question: Why are people colour blind?
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Stuart Archer answered on 17 Jun 2013:
It’s all to do with little cells at the back of your eye called ‘cone cells’ – these are responsible for allowing you to see in colour. There are three different types of cone cell and each type allows you to see a different colour – red, green or blue.
People who are colourblind have a genetic defect which means that one or more of these types of cell don’t work properly. It can also happen if your eye is damaged in some way (such as staring into a laser beam!) Red and green colourblindness is the most common, blue is quite rare. It’s 20 times as common in men as it is in women.
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Josh Makepeace answered on 18 Jun 2013:
You can do a test to see whether you have colour blindness. Basically you look at pictures which have a bunch of coloured dots, where some of the dots trace out a number in a different colour. People who are colour blind have trouble seeing some of the numbers.
Check it out: http://www.colour-blindness.com/colour-blindness-tests/ishihara-colour-test-plates/
Comments
catarinaperal commented on :
why do we see the kind of colours we see??
Stuart commented on :
We see the colours we see because of the cone cells I mentioned above – each one responds to a different colour of light – red, green or blue. It’s not quite as simple as that however, each of the cones responds to a range of different colours of light:
http://upload.wikimedia.org/wikipedia/commons/1/1e/Cones_SMJ2_E.svg
That graph shows the range of wavelengths of light – don’t worry too much about the details, what’s important is that blue light on the left and red light is on the right (think about the colours of a rainbow – red, orange, yellow, green, blue, indigo, violet). You can see on the graph that the red and green cells overlap quite a lot. When light hits the cells they send electrical signals to the brain. The brain then interprets these signals into the colours that you can see.
lollipopmika commented on :
If you are coulor blind what is the coulor that you will mostly not be able to see?
Stuart commented on :
Most people are red/green colourblind, meaning that can’t easily tell the difference between red and green. I imagine this would make all the colours at christmas a little confusing!
lollipopmika commented on :
He he, thanks. I’m glad I’m not colourblind!=l