I remember watching a video some years back where the researcher thought he had developed such a test.

As I recall (it's been many years; likely over a decade since I saw it) he tested it with a woman who was believed to have tetrachromatic vision. She could reliably tell the difference.

As a control, he tested it with a man who was trained as a graphic artist.

He too could reliably tell the difference.

That result strongly implied the test did not work as expected.

Do you know anything about this previous work? I tried reading the paper but was immediately out of my depth.

This is so cool. For your figures, how did you decide the RGB colors of the 4D colorspace? Or did you convince ACM to print your paper with special inks? :)

Definitely not the latter as the paper mentions "The digits are faintly visible in this photograph, because the camera’s color response differs from a human’s."