apeiron

This does not seem an accurate way to introspect about colour experience.

Green does not appear like a blue-yellow mixture but instead seems a pure colour experience.

On the other hand, you can have blackish blue, red and green (navy blue, crimson, forest green) yet not a blackish yellow. Instead you get brown from a low reflectance yellow.

Student demonstrated this with a chocolate bar viewed against a bright light backdrop. The brown turns yellow.

This is explained neurally by the fact we have three colour pigments but four colour opponent channels - so yellow is interpolated at a higher level of processing as a "primary" to counter blue. And the effect of relative brightness on colour experience.