• Question: why are some people colour blind

    Asked by dentrenator to Nazim on 14 Mar 2012.
    • Photo: Nazim Bharmal

      Nazim Bharmal answered on 14 Mar 2012:

      People are colour blind for several reasons. The human eye sees a few colours using rods in our eyes, and there are 3 (or 4 for some women!) versions: roughly, red, green, and blue. (This is a lot like how the CCD in a digital camera is made.)

      Some people can only make certain rods in their eyes so they are not so sensitive to some colours. For other people, they can ‘see’ all the colours because they have all the rods, but their brain doesn’t get the right signals so they find it hard to tell between certain colours. So that is another version of being colour blind.

      Finally, some people have synthesia, which is where they mix up colours, smells, and sounds. So they say that blue can “smell” like chocolate to them. Or that the sounds of a bell “looks” red.

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