I believe they do not alter the colour in the region being focused on, they're trying to take advantage of the fact that our peripheral vision is primarily rod-

I believe they do not alter the colour in the region being focused on, they're trying to take advantage of the fact that our peripheral vision is primarily rod-based, and thus unable to discern colour. So in theory, assuming the display can keep up with eye movements, it should never show you a tightened or limited colour range that you are actually capable of detecting through your eyes. I suspect it'll be subtly detectable in a couple of ways though, either through rapid eye movements (though I admit I have no clue how fast eye tracking/screen response can be), and secondly (more confidently) that your nose will shine green in the reflected glow of all the green pixels they're cleverly shining where you can't see them directly, and you can definitely see your nose.