erm...dunno Mirth - all the science boffin's say that we're only capable of distingushing upto 16million colours, just like we can only process upto 50frames per second.
I don't know about you but I have a knack for tellin' frames per second by how smooth movement appear, obviously above like 120 it is dang hard - but if you stare long enough you can notice. Just as with colours, if you look long enough you can tell the bands which is whole point in higher colour bits.
Personally don't think there is actually a limit to what we can percieve apart from that placed on ourselves, and if all we did all day is see things twice as fast would it look blured with double people like on TV or would be incorporate the extra frames as everyday life?
My Ki Jitsu tutor always used that annoying the hand is quicker than the eye saying on all of us, and yes at first quick hands could be too fast but after a while you brain gets used to processing movements faster - so I'm sure that we don't have really great limitations, its just they're things we never stretch oftenly.
Anata aru kowagaru no watashi! 
