It's more about what you're trained to perceive as opposed to what you're capable of perceiving. Plenty of gamers who regularly use 120hz monitors can easily tell the difference between 60 and 120 FPS. Particularly with games, where framerate also affects input response time. Once you've spent some time playing at higher FPS, lower will feel considerably more sluggish and imprecise.
Linus of LinusTechTips did a test where he setup a system running BF3 on a 120...
It's more about what you're trained to perceive as opposed to what you're capable of perceiving. Plenty of gamers who regularly use 120hz monitors can easily tell the difference between 60 and 120 FPS. Particularly with games, where framerate also affects input response time. Once you've spent some time playing at higher FPS, lower will feel considerably more sluggish and imprecise.
Linus of LinusTechTips did a test where he setup a system running BF3 on a 120...