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May 16, 2003
Coloured Signs
This comment should be prefixed by the equivalent of IANAL (I Am Not A Lawyer) but for physicist or optrician or something. I was waiting to cross the road and got thinking about the walk lights. In Sydney, we normally get the little men symbols - this is not being sexist - the stop symbol looks the same as the one used to identify the gents toilets. Anyway, the stop man is red and facing you, the go man is green and walking straight into the moving traffic. Think about that - he is walking at right angles to you - which means he is communicating the idea of walking but miscommunicating the direction.
In other places, the symbols (or words) are different but the colours are still the same.
The real question is why use red and green. If I can remember optics from doing physics in the dark ages (ie last century), there are three key frequencies in the eye when we view colour. These can vary from person to person but if two are closer together than usual, we get colour-blindness which is more properly an inability to distinguish certain shades as being different. Now given three points on a line, there are two gaps to consider: one gives the fairly common red-green problem (10%), the other leads to the rarer blue-green problem (1%). My main interest is that I am mildly blue-green colourblind. That means that there are some shades of colour that I cannot distinguish (and before you ask, yes I know that the sky is blue and that trees are green or if you are still in a punny mood: Teresa Green).
Surely there must be a better combination of colours that would work for lights. I understand about the red = danger combination but what about the green = safe idea. How about blue = safe instead?
Posted by Ozguru at May 16, 2003 06:05 AM
