Dangers of online Ishihara Colour Tests – Are you colour blind? Can you trust the online tests?

Using any test for recruitment has its problems. There are dangers of online Ishihara Colour Tests too. In a professional HR community I belong to there have been recent discussions about identifying if people are colour blind or not. This is historically because in some industries this is an important safety concern. In the past employers would use Occupational Health providers to do these tests. there are industry standards for this. The name of this test is the Ishihara Color Test.

Sites like http://www.colourblindawareness.org/colour-blindness/diagnosis/ suggest that online tests should only used as an indicator of potential colourblindness and to go to a qualified optician for formal confirmation.

In addition there is a problem, no two computer screens are the same.

When you look at the image below you will notice differences. The same site on 2 screens

Because there could be greater differences between screens. This difference could make an impact in the ‘test’ results.

The original test was actually printed using very specific colours on paper. Unless a properly calibrated monitor is used, never make a decision based on an online version. This include phone apps..

Getting technical about colours in print and on screen

On print we use a colour system called CMYK. On screens we use a system called RGB

There are some things that can be easily shown in print and not on screen and vice versa.

What humans can see in terms of colour perception

At close inspection you will notice that there are many green colours that can be reproduced in RGB but do not exist at all on CMYK.

Comparing what colours do not exist in RGB & CMYK

Green and blue are the colours that do not correlate well across the two systems. This is bad news for testing green/blue colour blindness.  Red also has its issues.

Graphics taken from https://graphicdesign.stackexchange.com/questions/49037/color-differences-between-monitors-and-print

Use of colour blind tests for recruitment decisions

If people are using online or app based ‘test’ for recruitment decisions take care not to. This could lead to potential discrimination cases, costing your employer £1000s.

Research on the original tests was done on paper print. The colours chosen were never designed for monitor use or different colour tones would have been used.

Testing children for colourblindness

Most of the tests online show only numbers or letters. there are professional tests available for children. The image below is such an image. What animals can you see. If your child cannot see all images, then take them to a professional – never rely on internet diagnosis!

Click on the image to get the full sized version – childs colour blind test sheet – animals – source http://freepages.rootsweb.ancestry.com/~hellmers/test/

Dangers of online Ishihara Colour Tests – Are you colour blind? Can you trust the online tests?