<p>Depending on the instructions that you give to the person, you might be able to disguise the fact that they are completing a color-blindness test. You could use stimuli like those in the <a href="https://en.wikipedia.org/wiki/Ishihara_Test" rel="nofollow">Ishihara test</a>, but instead ask the subject to do a math problem where they add the previous two numbers. You can also tell them that sometimes no number will be presented, and have a few cases of actual blank tiles mixed in with the regular stimuli. If a subject reports the wrong sum consistently for trials that involve a particular hue, you can be reasonably confident that they are colorblind for that hue.</p>

<p>There is also a short test developed by researchers at City University London which has subjects track a square during a movie. It's probably no more subtle than the Ishihara test, but it is less well known and therefore subjects might not infer what the purpose is. See <a href="http://www.city.ac.uk/health/research/centre-for-applied-vision-research/a-new-web-based-colour-vision-test" rel="nofollow">http://www.city.ac.uk/health/research/centre-for-applied-vision-research/a-new-web-based-colour-vision-test</a>.</p>

CC BY-SA 3.0
2014-11-06T14:30:13.560Z
2014-11-06T14:30:13.560Z
Josh
<p>Is there a test method of proving a person being color-blind, without letting the test subject know, that he/she is being tested?</p>

<p>E.g. showing the person cards with colored dots like depicted <a href="https://en.wikipedia.org/wiki/Ishihara_Test" rel="nofollow">here</a> is not a valid answer.</p>

CC BY-SA 3.0
2014-11-06T09:38:48.340Z
When you say the subject doesn't know they are being tested, do you mean know that color perception is being tested, or they are being tested for something?
StrongBad
CC BY-SA 3.0
2014-11-06T15:32:46.437Z
duplicate of http://biology.stackexchange.com/q/23733/460
Memming
<cognitive-neuroscience><methodology><vision><test>
A subtle test for color-blindness
Omnibus
# A subtle test for color-blindness

(Asked by: username_0 on 2014-11-06)

Is there a test method of proving a person being color-blind, without letting the test subject know, that he/she is being tested?

E.g. showing the person cards with colored dots like depicted [here](https://en.wikipedia.org/wiki/Ishihara_Test) is not a valid answer.

**Tags:** cognitive-neuroscience, methodology, vision, test

> **Comments:**
> **username_1**: When you say the subject doesn't know they are being tested, do you mean know that color perception is being tested, or they are being tested for something?  
> **username_2**: duplicate of http://biology.stackexchange.com/q/23733/460  

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## 1 answers

### Answer by username_3 on 2014-11-06. Score: 2

Depending on the instructions that you give to the person, you might be able to disguise the fact that they are completing a color-blindness test. You could use stimuli like those in the [Ishihara test](https://en.wikipedia.org/wiki/Ishihara_Test), but instead ask the subject to do a math problem where they add the previous two numbers. You can also tell them that sometimes no number will be presented, and have a few cases of actual blank tiles mixed in with the regular stimuli. If a subject reports the wrong sum consistently for trials that involve a particular hue, you can be reasonably confident that they are colorblind for that hue.

There is also a short test developed by researchers at City University London which has subjects track a square during a movie. It's probably no more subtle than the Ishihara test, but it is less well known and therefore subjects might not infer what the purpose is. See <http://www.city.ac.uk/health/research/centre-for-applied-vision-research/a-new-web-based-colour-vision-test>.


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