JimL,
Pick up a copy of Dave Grossman's book
On Combat, which discusses a lot of the perceptual phenomena related to high-stress situations, particularly the high stress of combat.
Or take a look at Alexis Artwohl & Loren Christensen's book
Deadly Force Encounters, which details a lot of the more recent research in the field.
Or see David Klinger's
Into the Kill Zone: A Cop's-Eye View of Deadly Force which provides some great stories from an in-depth study that Klinger did related to cops involved in lethal force encounters; it puts a human face on the dry research and gives a very clear picture of the sorts of things people experience under stress.
Or visit
www.forcescience.org -- the Force Science Institute -- to receive a very informative free newsletter tracking some of the current research.
Lots of other good material out there too, if you look for it.
pax