Talk:Ishihara test

Extra info - discrimination in Japan
This test, aside from its scientific value, has long been applied to institute kinds of social discriminations in Japan, and probably in other countries as well, throughout the 20th century. Particularly before 1950s, those who failed to pass this tests were excluded from engineering schools, military services, and other professions considered needing the ability to differentiate colors. It was a celebrated story that one of the kins of the fiancee of the late Emperor was found to be colorblind, as the test was first applied to the students of the royal school. In spite of the rampant objections within the royal household raised against the marriage, since the colorblindness became known to be hereditary, the Emperor persisted to fulfill the engagement. He was long praised for the decision, and the episode contributed greatly to remove the baseless discrimination caused by the wrong way of application of the test.

Constructing the designs
How are the "patterns and colours of dots" selected so that they present the various different numerical/non-patterns? (For these or "any other similar designs.") Jackiespeel (talk) 21:33, 20 April 2008 (UTC)

"Ishihara Plate No. 19 (2)"
The Ishihara Plate No. 19 in the gallery doesn't show a 2. It shows nothing. People with red green color blindness can trace a line (and don't see a 2 or any other number). --StYxXx (talk) 08:05, 29 July 2013 (UTC)


 * I can see a "2" in plate 19 quite clearly. I appear to have mild Deuteranopia according to the tests.129.78.233.212 (talk) 08:51, 10 September 2013 (UTC)

Exact! The Plate No. 19 presented here does not correspond to standard Ishihara Test. In this image, a person with normal vision can see clearly "2", and a person with color blind to red/green may not see anything. The Ishihara Plate is not the same: http://www.dfisica.ubi.pt/~hgil/p.v.2/Ishihara/Ishihara.24.Plate.TEST.Book.pdf Andreluis7mmv (talk) 14:22, 27 January 2015 (UTC)


 * Huh what do you mean exactly? The plate No. 19 featured in this article clearly doesn't show anything for people with normal color vision. It will show "2" for people with color deficiency. The one in your pdf file is a tracing plate, and people with normal color vision also can't see anything there, but color blind people will see a line and can trace it.--  Krystaleen  14:58, 28 January 2015 (UTC)
 * I've got a feeling that this image is wrong, or the colour hues don't work so well on monitors. It's not part of the standard test and the thumbmail clearly shows a 2 even to a person with normal vision. It's harder to see on a full size image but still present. This is the standard plate 19. http://www.colour-blindness.com/CBTests/ishihara/Plate19.gif and a normal colour vision person does not see anything in it.  — Preceding unsigned comment added by 109.81.208.231 (talk) 18:29, 7 March 2015 (UTC)


 * Looking at the edit history on Commons (https://commons.wikimedia.org/wiki/File:Ishihara_19.PNG), this image has been swapped between two similar patterns, one which has a blue "2" broken by lines, and one which only has lines. I assume some versions of the test have a numbered plate as plate #19, and others have a numberless "tracing plate".
 * This article could use more detail about the tracing plates (which were only mentioned obliquely before today), and whether they were always a part of the Ishihara test, or added later. I assume they exist so that the test can be used on subjects who don't recognise Arabic numberals? --Lord Belbury (talk) 10:35, 17 June 2020 (UTC)
 * The test would be useless for anybody that doesn't recognise arabic numerals. -Roxy the elfin dog . wooF 11:39, 17 June 2020 (UTC)
 * I mean the numberless tracing plates (pictured in the article as plate #19), where the subject is asked to trace an unbroken line rather than read a number. --Lord Belbury (talk) 12:13, 17 June 2020 (UTC)


 * It's also only plate 19 in the reduced 24 plate version. In the full 38 plate test it is found as plate 29, often rotated 180 degrees from what is shown. Gsuberland (talk) 13:06, 29 June 2021 (UTC)
 * This appears to be the only plate referred to by this article that uses the 24 plate numbering, so I've changed it to say 29 and added a note about numbering discrepancies. Gsuberland (talk) 13:42, 29 June 2021 (UTC)

Scientific Write Up?
Has anyone come across an academically written write up of the experimental process Ishihara went through to create these plates. I'd be very interested to read such, and I think this page would benefit from a link to such.Da5nsy (talk) 14:36, 6 May 2014 (UTC)

21? seriously?
I'm 99% sure this is 74 x.x ; modify hue & saturation, and it looks obvious.

Divinity76 (talk) 10:32, 4 November 2014 (UTC)
 * "Example of an Ishihara color test plate. The number "74" should be clearly visible to viewers with normal color vision. Viewers with dichromat or anomalous trichromat may read it as "21", and viewers with achromat may see nothing." Protonk (talk) 14:47, 4 November 2014 (UTC)

We have to be a little careful here as the Ishihara images have been changed and replaced over the years and the "obvious" point above might be talking about a different version (in 2014 the image looked like this), but given the current version on the image on the right, is it correct to say that some viewers will see either 71 or 21?

I can half see that the brown circles to the right of the base of the 7 could possibly "fade in" to certain viewers, with there being some similarly slightly-off brown circles higher up between the two numbers, but are we sure that's a deliberate part of the design rather than an artefact of its creation? It looks like a very minor change in pigment to me. Are you correcting the caption to 21 from personal experience of how it looks to you, User:JsfasdF252? --Lord Belbury (talk) 22:14, 24 November 2020 (UTC)

there is definitely a 2, it is not an artifact, the discoloured redder circles are very intentional (and intentionally subtle); they might not be intended to be obvious to all colour-blind people, but people who cannot perceive the 4 around the 1 at all won't see the 7 at all either, and the darker parts of the 7 will stand out, to be completed by the redder circles into a 2 A Wingless Monkey (talk) 15:43, 17 December 2020 (UTC)

Looking for sources, I've found a few textbooks that talk about 74/21 as a pairing of legible numbers in the test, and this one shows an image which is fairly similar, and just as surprising to me that it forms 21 rather than 71. I'll update the article accordingly, using that source. --Lord Belbury (talk) 16:12, 17 December 2020 (UTC)

Ishihara test external links

 * copied from User talk:Glrx/Archive 10
 * RE: my revert that restored an external link to an Ishihara-like test website

I removed the link you reverted back, as it is obviously self-promotion, you can see it was added in this edit, you can see in the user's talk page and contributions page to check, Jjean3~enwiki — Preceding unsigned comment added by 200.127.180.78 (talk) 18:59, 31 December 2016 (UTC)


 * I do not see this link as obvious self-promotion. I see a reasonable optician providing an interesting application that helps explain Ishihara-like tests. The optician is not selling the application but rather making us aware of it on a relevant page.
 * The link you show was reverted by Ronz. The link was discussed at Talk:Color blindness/Archive 2 with mixed results. The link was reinserted by an IP in this edit in 2008. The link has been around for 8 years. There was no discussion on the Ishihara test talk page.
 * Even if we concede the two editors who added the link are the author, that is not necessarily bad. Yes, there is a WP:COI. Yes, it has a copyright notice that identifies the author, but the question is whether the work is reasonable to include. The offered test is much more extensive than the Toledo-bend website test, and the test evaluation attempts to distinguish the -anopia and -anomaly types of colorblindness. After taking the test, there is a discussion of how different symptoms interpret the images. Consequently, it discusses in more detail how results from Ishihara-like tests are interpreted. That is not addressed in the article.
 * Yes, the link uses advertisements to support the website, but the focus is on colorblindness. The primary goal of the website is to provide information. The website is based on sources because it apparently references two tests (Wickline?).
 * I see WP:ELYES #3: site has apparently accurate information.
 * I see WP:ELMAYBE #4: not an RS but still has knowledgeable information.
 * WP:ELNO #11 arises because it may be a personal website, but the author claims to be an optician, and the site covers several topics appropriate for opticians.
 * It is a tool that runs through some Ishihara-like images, collects answers, and then provides some interpretation of those answers. It is reasonable to include in the Ishihara article.
 * Not an issue, but the link is also present on fr.WP: Daltonisme.
 * Glrx (talk) 21:36, 31 December 2016 (UTC)