It depends on the person and the application.

For most people, when it comes to film, 24 frames a second is the minimum necessary for it to be perceived as fluid motion.

With a video game, where the user controls the input, 30 frames per second is typically the minimum target necessary for fluid motion; but personally, I only see it become truly fluid at 60 or more.

You can certainly see a lot more than that and reality doesn't really operate on frames per second, so there's no way to know how many FPS becomes more than you'd ever perceive.