30 vs 60 fps - can you really see the difference?

[COKTOE]

I find it mind blowing that there are people that cannot make the distinction between 30fps and 60fps. It seems rare, but I've encountered it enough to be able to say that people I know have trouble doing it. For me, it's ridiculously obvious. I suppose they must have some sort of limitation or slight impairment that makes this so. Of course, at around the 60fps mark, the more fps that are added on, the more the law of diminished returns kicks in. But 60 vs 30? Easy to tell.