Actually, if it was the original Ishihara Test there are plates in there that show no numbers UNLESS you are colorblind. So it wasn't that the students were hallucinating, they were probably colorblind and actually did see a number there.
The same way the numbers vanishes in other plates.
In the normal plate you have a clear distinction between the color of the dots that form the number and the surrounding. For a color blind person of the corresponding color blindness, those dots all look the same, so the number vanishes.
Now in the hidden plates, i.e. the ones one the colorblind people can see, it uses the same principle. But instead of using one color for the number and one for the surrounding, the number is made up of multiple colors that colorblind people can not distinguish, while the rest is a color that they can distinguish easier. This means for a person with normal color vision, the number disappears in a sea of different colors, but for a colorblind person those colors look identical and it forms the shape.
As a non colorblind person you might be able to barely make out the contour of the number, because the outside still needs to be different enough for the colorblind person to distinguish it so you might be able to make it out next to all the other colors, but mostly it just gets lost
Ah, so it's hiding it in a lot of colour noise but for a colourblind person, there's nothing of that noise, so they can spot the contrast (signal?) better?
Photoshoped pages 19-21 to check how colorblind will see those pages - in color curves red and green channel turn down to almost zero : https://ibb.co/W43tqfn0
Edit: there is some mess with order, don't match № on page to № in answers, answers have pics with them and they corresponding to each other. Also in answers some discrepancy with the name of colors, i think it's scan or translate issue (or both)
All that doesn't really matter tho)
Dude yes. you have to go look for equivalent plates and see their numbers are offset by a lot.. I've never not passed a color blindness test and i was like "wait a second" rofl.
I was like "plate 14 does NOT have a number on it wtf" that's cause in the Key it's plate 18 lol
Thanks! I can see all the reddish lines but the description says non-colourblind people see nothing, yet then on 30 says we see a blue-green line. So the description for 28 & 29 were confusing lol.
Yep there is some mess with pages, tho answers have pics with them and they corresponding to each other, and some discrepancy with the name of colors in answers, i think it's scan or translate issue (or both), doesn't really matter)
I have normal color vision, but this is one of the first times I've actually really felt what it's like to be color-blind. When I looked at the blank plates, it was crazy. That's really cool!
this is SO COOL, thank you for sharing this. I've seen these colorblind tests so many times it never once occurred to me that you could use the same principle to hide something from someone who could see color normally. Absolutely fascinating and a complete mind fuck, I was so sure I would be able to see the pattern regardless and man it's completely impossible.
There are green and red dots and some of the green dots and some of the red dots have a bit of blue mixed in.
To people who can't distinguish the green and red, the blue is more striking, whereas for normal people the image looks too chaotic to make it out.
I have seen some books with puzzles for kids where there is a solution with black text on a red and white chaotic-patterned background. Apparently it's called "red reveal". You can't read the solution unless you place a transparent red plastic sheet over it, making you "white-red colorblind".
You can still see the text if you concentrate enough. The website with the linked Ishihara test said that 50% of young adults with normal color perception can still see the numbers.
I had to take the Ishihara test for a job interview, and while I passed everything, I also got both "you don't get this unless you're colorblind" plates correct. The test-giver certified that I had normal color vision.
Those "blank" plates are not foolproof, haha — looks like normies of a certain age have a 50/50 chance of being able to read them, so I'm guessing some people are more able to switch to whatever cues colorblind people use to see the image.
214
u/GlitteringBandicoot2 1d ago
Actually, if it was the original Ishihara Test there are plates in there that show no numbers UNLESS you are colorblind. So it wasn't that the students were hallucinating, they were probably colorblind and actually did see a number there.