Along with about one in twelve men and one in several hundred women I suffer from a degree of colour deficient vision, or colour blindness.
I don’t find it a major handicap, despite the fact that I actually work with colour as part of my job as a cartoonist. But then accuracy in colour use isn’t exactly a top priority for cartoonists as long as the joke’s okay.
Here’s a manifestation of the particular type of colour deficiency that I suffer from.
I can be walking in the park with someone and they’ll look at a holly bush in the distance and comment on how wonderful the red berries look. I’ll look at the same bush and see only green. No berries. We’ll walk closer to the bush and as we get nearer I’ll start to be able to make out the berries. By the time we’re standing next to the bush I can see the bright red berries as clear as daylight.
The point is, that although I suffer a form of colour deficient vision that makes reds tricky to perceive, it’s not that I can’t see reds at all, it’s that there has to be more than a certain amount of red to see before I can see it. A small amount of red just doesn’t work – it doesn’t stimulate the red receptors in the eye enough to register. The volume has to be turned up before I notice the colour.
With this ‘volume’ notion in mind I recently decided to conduct an experiment to see if I could ‘improve’ my results in a colour blindness test.
I found a suitable colour blindness test online. There’s a link to it at the bottom of this article.
The test involves a display of coloured squares in a row (see image).
The squares are all slightly different colours, and are arranged randomly. To conduct the test you have to rearrange the squares so that the colours change sequentially, changing smoothly from one colour to the next.
You then get a score for your efforts, starting with a top score of zero if you get the squares in exactly the right order, which shows that you can differentiate between colours that are very similar to each other, and going down to over a thousand if you can’t differentiate between the colours at all.
It’s an enjoyable test. You should try it.
By the criteria of the test, colour deficient vision is defined as a score of 100 or more.
My own attempt at getting the colours in order gave me a score of 109. This is above the test’s threshold for defining colour deficient vision, and was the sort of result I expected.
Then I redid the test, but this time with the ‘volume’ increased so that I saw more colour.
To do this all I did was to increase the size of the squares on the screen by zooming in on the image. The magnified squares were about the same size as in the image below.
This time I got a score of 58. Exactly half my previous score of 109. By the definitions of the test, that’s well within the range of ‘normal’ colour vision, even though I know that I’m colour deficient.
This isn’t a flaw in the test. Basically, I was cheating. The test is, I assume, calibrated to be done with the squares at a specific size, precisely because the results will be different if they are viewed at a different size. Or for that matter, at a different brightness, as colour vision is better the brighter the colours.
Have a look at the X-Rite colour blindness test