And when asked to find the green square in a field of different shades of blue, the members of those tribes do fairly poorly, as most of us would be asked to pick out a particular shade of blue from other shades of blue.
interesting.. I thought the "rainbow" was universal. ROYGBIV
That is, they don't just use one word for both colors, they seem to actually see green as just a shade of blue.
hmmm. there are discrete values for visible light - nanometer wavelength
https://en.wikipedia.org/wiki/Visible_spectrum
maybe they don't have words for it, but their eyes should be capable of distinguishing
485-500 nm = cyan
500-565 nm = green
green square in a field of different shades of blue
wonder if they'd do better if you gave them a green one and find the ones that match... instead of "find the green ones. "