● Colour Blindness (Andrew Oakley) http://www.delamare.unr.edu/cb/

● Firelily Designs http://www.firelily.com/opinions/color.html

● Vischeck http://www.vischeck.com/index.php

Most of us take colour vision for granted, but there are still many people who are unable to enjoy its benefits. One in 20 European Caucasian males has a red/green colour vision deficiency, and the internet provides plenty of useful information about this and other types of colour blindness.

Many colour blind people feel that they are discriminated against. Andrew Oakley, who is red/green colour blind, says “we have instructions telling us to 'press the red button', machines which have a green safety light and a red warning light, even colour-coded pills!” He also vents his spleen on light bulbs that change from red to green, which he calls “the work of Satan”.

It seems that we need a better understanding of the needs of people with colour vision deficiencies. For example, Diane Wilson from the web design company Firelily Designs offers advice on how to make your web site more user-friendly (handy hint — see how it looks in black-and-white!). Wilson herself is an 'anomalous trichromat'; that is, her red and green cone cells do not function as effectively as they should. If you want to see how your own web site looks to someone with red/green colour blindness, try running it through Vischeck.

Although colour blind people are prevented from doing certain jobs, it's worth noting that they might have certain advantages. Oakley points out that “we look for outlines, not colours, so we don't get easily confused by camouflage”, which is why “colour blind people were used in World War II spy planes to spot camouflaged German camps”.