Crude Colour Blindness Indicator

Taking yesterdays research a bit further, I have devised a crude colour blindness indicator for use with my own students. I don't claim that it can be used to diagnose, but it would certainly work well enough to indicate where there may a problem and where further, qualified diagnosis may be prudent. Most importantly however, it helps me as a teacher have a better understanding of my students colour perception so I can better support them in areas where they may struggle.

I got on to this when I found out, purely by chance, that a colleague in another department was colour blind. It occured to me that if he looked at the image in yesterday's blog post that two of the four colour wheels would look identical. They being the colour wheel that simulated his colour blindness type, and the original. To him, they should look the same. This being the case, it would make a very simple (if crude) colour blindness test, and even give some indication of the type.

Here's how it works

Candidates would all be presented with this set of colour wheels (minus labels of course - we don't want to suggest answers).
To people with "normal" vision, the first wheel would appear to display the full spectrum, while the Protanope and Deuteranope simulations would appear similar, though not exact. The Tritanope simulation would look very different.

However, to people with Deuteranope (red/green deficit) colour blindness, the set would look like this:

While three of the colour wheels will look similar, two will have a closer match, the simulation of Deuteranope colour blindness and the original colour wheel.

To candidates with Protanope (red/green deficit) colour blindness, the set would look like this:

Again, while three of the colour wheels will look similar, two will have a closer match, this time the simulation of Protanope colour blindness and the original colour wheel.

Finally, to candidates with Tritanope (blue/yellow deficit) colour blindness, the set would look like this:
While all four colour wheels look similar, two have a definate closer match, this time the simulation of Tritanope colour blindness and the original colour wheel.

So, back to the beginning, by showing candidates the set of four colour wheels - one normal, and three adjusted to simulate different colour blindness types - a simple indicator test is produced.

The candidate is simply asked to point out which two colour wheels are most similar, and an indication of the presence of colour blindness (and possibly type) is arrived at.

I tried it on my colour blind colleague, and it seemed successful in that he really did see two circles as being the same, indicating him to be of the deuteranope colour blindness type. Another colleague with a less severe colour blindness (he only confuses certain greens and certain browns) was, according to this test "normal". So it really only indicates a problem when it's severity is more pronounced.

Spurred on by today's success I have compiled the test into a single double sided A4 sheet. You can download it here in PDF format >



One word of caution. This test has been devised by me, an experienced graphic/interactive media designer turned teacher. But I have no qualifications regarding colour blindness. Perhaps some kind scientist/researcher with more experience will come along and verify or refute my observations. Meanwhile I will use this method to help me understand the needs of colourblind students as and when I get them. If nothing else, it gives me some idea of their colour confusion, and will allow me to take it into account in supporting my students.