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 is not a valid answer.


closed as off-topic by kmm Nov 8 '14 at 15:29

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    $\begingroup$ How do you want to do this without test charts? You can only observe the person how it reacts on certain colors. If you can't ask directly, this will be hard. $\endgroup$ – Chris Nov 5 '14 at 16:28
  • $\begingroup$ i'm sure you could think of something, but the standard tests require asking questions. just make a sign with two colors that would not be distinguishable and ask them to read it. $\endgroup$ – shigeta Nov 5 '14 at 16:30
  • $\begingroup$ Once my chemistry teacher , who is colour-blind, said...that the doctor during a standard eye test, told him nothing about colour-blindness, but showed him a chart, on which it was written- " I am not a colour-blind"....then when he was asked whether anything was written on the chart, he confidently & obviously unknowingly said "No"... $\endgroup$ – souvik bhattacharya Nov 5 '14 at 19:22
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    $\begingroup$ Build a tiled floor with red and green tiles, write a really bad word with the tiles. Look for people who don't respond, then filter out the non-blind individuals who are too jaded to care. $\endgroup$ – user137 Nov 5 '14 at 23:26
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    $\begingroup$ Maybe the cognitive sciences SE may be a better platform for this question? $\endgroup$ – AliceD Nov 6 '14 at 1:46

I am colorblind, but I did not know that before I was 22 (!!). I got to know it by doing the Ishihara test. There are other tests you can do to test for colorblindness, such as the reverse colorblindness test (http://www.cs.unm.edu/~aaron/creative/colorTest.htm), where a "normal vision" person will not see the two patterns shown there.

Anyway, there is no test where you cannot ask "what do you see?" to the subject. On the other hand, I saw a photo where they were showing a northern light in both colorblind and normal vision (https://www.facebook.com/nlblog/photos/pb.236481989828593.-2207520000.1415264974./416457851831005/?type=1&theater) -I hope facebook links are OK in this site-, where I see no difference between the two photos. You could for example show that photo pair to your test subject and ask a set of questions (e.g. which one do you like more?). If he/she is colorblind, then the answer will be "they are the same", so you have a strong indication, or if they are able to point out differences, then they most likely have normal vision.

I could think of an experiment where you just show several photos with different contrasts/saturations, and then add the northern light photo (maybe the author has some other photos you could use), so they are not aware of the underlying question.

I hope this helps

  • $\begingroup$ I appreciate your hints (can't vote up, my rep is not high enough on this site). Actually I'm looking some method that is already scientifically proven. $\endgroup$ – Omnibus Nov 7 '14 at 11:24

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