"able to distinguish" is a very ambiguous description. Imagine the following scenario: you play a video game, where you are a cowboy in a standoff, as soon as y

"able to distinguish" is a very ambiguous description. Imagine the following scenario: you play a video game, where you are a cowboy in a standoff, as soon as your opponent grabs his gun, you need to click to shoot yours. You are punished for a false start, and rewarded based on your reflexes (maybe statistically: the sooner you shoot the more likely you're to win the duel). There is no lower bound to latency, and therefore upper bound to FPS, that helps you statistically. Eventually the resolution of the study (e.g. sample size and therefore the statistical error) will say that "the population are able to distinguish" up to some Hz refresh rate. But when you then increase the resolution of the test (sample size), you will again start to see a difference. Of course I'm not saying a research like that wouldn't be interesting, all I'm arguing is that there's no definitive answer about maximum FPS that makes sense.