[hilbert42]

This test is useless or of very limited value.

I kept pressing green until the end because you had no 'cyan' button to press when clearly many colors were actually cyan. Cyan is not blue.

Incidentally, my color vision is perfect on all Ishihara tests.

[nobrains]

Blue and Green and primary and secondary colors.

Cyan is not. The author decided to cut off the colors list at secondary colors. There is nothing wrong with that.

[hilbert42]

"The author decided..."

'The author decided' is not physics. Suggest you look at the Wiki page under 'Wavelength': https://en.m.wikipedia.org/wiki/Color_vision

Green: 500 - 590nm, Cyan: 485 - 500nm, Blue: 450 - 485nm.

Color vision theory is far too complicated to discuss here, and I'm not going to debate cyan as a mixed color of blue and green wavelengths versus a fixed wavelength that's in between both of them.

What the author provided was, at best, misleading but nonsense as far as science is concerned.

If the author said he was an artist and presented colors as a preferential list it would have been a different matter.

BTW, I don't mind being voted down (it happens to me regularly), but here those who did are only showing their ignorance. I'd add the author—who penned here—ought to explain his actions in much more detail.

[digging]

Not to be mean, but I think every assertion in your comment is wrong.

Blue and Green are English words which sometimes describe primary or secondary colors additive colors. Cyan is (an English word that describes) a primary subtractive color.

Colors are not English words. They're physical reactions inside our eye-brain systems, affected by varying wavelengths of light. (Actually that's not the most accurate description of color either, but it's a more useful model.)