When recording moving pictures, the film is composed of a set number of frames recorded per second (24 for most films), with each frame exposed for a set amount of time (shutter speed). It seems to me that human vision is more fluid, both not locking onto rigid frames and not locking onto a set "frame rate" (for want of a better term), or recording at a set (effective) shutter speed.
So - assuming that we take in information on an as-needed basis, it stands to reason that the brain would automatically dial up the effective visual frame rate in times of danger, high-speed action, etc., and dial it down in situations/scenes with little need for attention to surrounding visual details.
Nevertheless, in spite of having variable speed visual perception, there's a sense/belief/perception of seeing at a constant rate, so when you combine that with our assumption that time flows forward at a set rate (watch the second hand on a watch for a demonstration); when we are in increased-frame-rate mode, it distorts our *perception* of time passing and very short intervals can seem to last a very long time.
Conversely, when in reduced-frame-rate mode, it distorts our perception of time passing and rather long intervals of time can seem to last for a very short time. Another factor of reduced-frame-rate mode is that as people get older, their vision gets less sharp, so they're taking in less detailed information, and this also pushes perception towards reduced-frame-rate mode.
There are mountains of details to go into, but I'm out of time today, so I'll post just this for now.
Here are a couple of links to time-perception that are basically the same thing - from a wide-field perspective (not confined to vision):
Why Does Time Fly By As You Get Older?
Sore dewa, mata!
Copyright 2012 by Lyle H Saxon
Lyle (Hiroshi) Saxon