Huh. I consider cyan to be blue, but it turns out it's made by mixing equal parts of blue and green light on an RGB display.

I guess that makes sense thinking about it now since it's not a deep blue, and there's obviously no red component, but I never thought of it as being defined as equal parts blue and green.

(Turquoise I would consider to be blue-green/both).

How would you feel about a test for "teal or blue" or "teal or green?" You still need to make binary choices, just along different boundaries. Would it make any difference?

Incorrect, it either lies on the blue side or the green side, you must choose. Neither is not an option.

I don't think that's necessarily the case. I understand that there's a continuum in reality, but psychologically, I still tend to perceive each shade as discretely either blue or green, especially when the shade is presented in isolation. Words like "teal", "cyan", etc. aren't really part of my normal vocabulary and to the extent that they are, I would think of them as subsets of blue or green, not disjoint sets.

I think the test can be fairly criticised on the basis that it is assuming everyone's psychological colour space has a discrete boundary between blue and green, which clearly isn't the case for some people (like you), but it is for others (like me).

It is enlightening to see who has been fixed on math proofs as testing and who has been exposed to observational testing. Seems many people have been brain washed into the former, forgetting the latter exists.

Or suspension of expectations…