Mike at hdforindies beat me to the punch on this one. Adam Ecker and Laurie Heller have put together a video demo at Cognitive Daily that illustrates human auditory/visual perception entitled What We Hear, and How It Affects What We See. Snip:
In movie fight scenes, punches often miss by a foot or more, but when sound effects are added, and the punchee adds an effective-looking recoil, we're convinced that the punch is "real."
This little cheat of human perception, in conjunction with persistence of vision, allows cinema and video to "work" in our brains. For more info, you may want to check out this essay about Gestalt Theory. Snip:
...visual perception also changes over time, when we look at moving or changing forms, even when we see a static image our eyes move across it in meaningful patterns. Further, our two ears allow us to detect distance and direction, and our musical sensibilities perceive movement in a space defined by such dimensions as timbre, pitch, duration, distortion, resonance and so on.
Link to demo, via dvguru.com (thanks, you will be missed), hdforindies, et al.
Link to Gestalt Theory essay.