Quote Originally Posted by Scud View Post
It's more common than you think, around 8% of males are colour blind. The red-green tag is mainly just the offical term for the type of colour blindess (as in not total colour blindess which does exist but is far rarer).

I personally, which I'm sure is true of others, have problem seeing the difference between similar colours/shades when they are close together. For example, if red (depending on the shade) and brown side by side they would look the same, the same with dark blue and purple, light green yellow/orange to name a few.

You would not know how frustrating it is with colour-coded puzzles in video-games and when using programs like Paint/Gimp when it comes to trying to get the right colour to use.

And yes....I can see traffic lights perfectly well before you ask!
I'd like to add.

It is also known as Daltonism.

And it isn't that we don't see red or green or can't make the difference at all. We just see colours (some or all) different. We've been learning from childhood that that certain frequency of light is named by that word, so we can tell this is red and this is green. It is only when certain shades are rather similar that trouble begins.

My hardest problem is seeing red letters on dark powerpoint presentation backgrounds or blackboards.
When there isn't enough light I also can't see the difference between red or green ink or pencil writing on a paper.