: Perhaps it's the difference between seeing a difference in a period time
: versus actually distinguishing individual frames? Say you're able to
: distinguish 100 individual frames per second. You could still tell if
: something was 300fps, because it would be blurrier (each distinguished
: 'frame' would be composed of 3 actual frames, compared to 1 at 100fps).
: But you'd still only 'see' 1 distinguished frame.

: I think the issue is that yes we can tell 72fps apart from 120fps or greater
: and whatnot, but do our brains actually see every single frame, or just a
: blur of frames each? (based on whatever scientifically determined frame
: rates)

Well that's the exciting question.

Here's how we answer it:

1-Create a system that renders a windows desktop with "perfect" framerate-dependant motion blur on the mouse.
2-See if people can still distinguish 60/120/240/480/whatever FPS against each other.

It would be a hard test to be sure to do right though. There's all kinds of stuff you'd have to think about, like making sure your motion blur levels are reasonable and aren't perceptibly making the image blurrier than an infinite-framerate non-motion-blur image would be (Obviously you could make even 30fps look perfectly smooth if you just smeared everything horribly). You'd also have to run the test on displays with very non-blurry motion response, like CRTs or plasmas.