Movies look reasonably smooth at 24 frames per second; unless the screen is huge and you use your peripheral vision, you usually can't see each frame individually. This has lead to a large amount of textbooks claiming that the visual response time of the retina is slower than 1/24 seconds.
However, games at 24 frames per second absolutely suck. The motion is so choppy it is unplayable. For a game, you seem to need at least 40 frames per second, and even at that rate you still see individual frames if the objects are moving quickly.
Why is this so? Is this related to the fact that movies have motion blur due to a non-zero shutter speed? Is "jerkiness" mostly perceived in terms of "gap between object in frame 1 and frame 2" rather than visual response time (the gap is smaller in films due to blurred objects "connecting" across frames)? If so, doesn't this prove that our visual response time is much faster than 1/24 seconds?
To make the question more precise: is this response determined by physical mechanisms, such as the relaxation times of pigments in the eye or the firing times of neurons? If so, which ones? Or is it mostly due some sort of postprocessing done by the brain, i.e. more to do with the cognitive than the physical side of perception?