The Science Behind The Ishihara Test

Pseudoishochromatic Plates - including the famous Ishihara Plates - are the most common type of test used for detected colorblindness. This video will explain how they work, why they look like that and how to make your own.

Footnotes and Transcript:
Glossary, including most of the technical terms in this video:
PIP Generator:

[klikkolee]

I saw the 6 before you mentioned that it changed to a 6 and was hoping for a color-perception explanation of why a 5 looked like a 6

[jumpander]

At 6:20 I saw a 6 but my brain changed it into a weird 5 because that's what it expected.

[TravisPeriod]

I really appreciate your channel. Thanks for breaking things down in a way I can explain to other people what being a "severe" deutan really means. Saying "pink and gray are identical" confuses then even more. lol

[IcelyPuzzles]

heh, nice stuff with the 5 at the end lol
I thought I saw a 5, but did note that the top left diagonal of the '5' looked a bit oddly angled, so good prank. even then, the extra line for the 6 is thinner

[SkeletonSSBM]

Oh my god I got totally memed when you switched the 5 to a 6

[gideonwharton]

can you please do a tutorial on how you made the color blind test and what software did you use

[itay]

I'm a colour normal but I stumbled upon your channel recently and I'm really enjoying your content! Very under appreciated! Just came to say I'm intrested in cheating the Ishihara test, and maybe could you show off alternatives while you're at it?

[menoflowicz]

6:33 I see the "6" on the simulation (yes, very distorted, but I see difference in color) while I don't see it on the original :P (I have mild deutaranomaly).

[Garfield_Minecraft]

6:17
I see nothing
But in big one is 6
And on top 5(if i don't see 5 i think im hecking blind)

[BrianAgbay]

Is there a version of the CIE 1931 color space diagram which has been adjusted to be isoluminant?

[aev]

the middle seems easier than the bottom

[stephenmk]

I wonder if the isoluminant point varies from one person to another with CVD… perhaps based on cone counts / expression somehow. I have a set of cousins, three boys, that each had their own apparent color confusion patterns. Their mom thought it was three different types of colorblindess and I had trouble explaining why that didn’t seem possible genetically. Just an odd case. Also, looking forward to a reverse ishihara vid / script… would love to know how those work

[maczajsci]

Can you give the link to the reverse plate generator?

[brendan]

Why is it that a copunctal point exists, from which all the lines of confusion radiate? Or is that just more of a theoretical approximation? I would have thought the lines of confusion would be a little wavy or irregular.

I could still see the number (and yea, I noticed it was a 6!) on my screen, both on my external monitor and laptop built in. they are both pretty bad monitors, tho.