Excaliber: Excellent posts and excellent subject for a Topic.
I don't have much to add, but you know that I'm seldom without some opinion to yammer about.

And apologies in advance: I wrote this offline and it got away from me; you thought
your post was long...
Excaliber wrote:Folks who have been involved in 2 or more violent encounters tend to see diminished effects in subsequent incidents, perhaps because they aren't as stressed as someone exposed to his first incident.
I think that noting the individuality of experience is important because folks can't afford to make the assumption they will react exactly one way or another; and even a second experience in nearly-identical conditions and circumstances can result in somewhat different reactions.
An individual's physiological baseline also comes into play. Age, fitness, and general health are three factors. So even disregarding context-specific training, there are things one can do to help improve the body's ability to handle rapid-onset, extreme stress. Another factor is any artificially-introduced chemical cocktail. Alcohol, prescription medication, and even caffeine all affect the physiological starting state.
Also in play are environmental conditions at the time of the event: temperature, altitude, brightness or darkness, ambient noise, footing or lack thereof, etc.
Another observation that I believe can be useful is to differentiate among "reflexive responses," "instinctive responses," and "trained responses." Just my own terminology and just MHO, so take this with a grain of salt.
Reflexive responses are essentially the same, barring differences in magnitude, across (almost) all individuals. I say "almost" because there are some folks whose wiring is different...or messed up. For example, someone with Cushing's syndrome or adrenal hyperplasia will have radically different reactions to rapid-onset stress. A sloppy drunk doing his best to keep his body balanced underneath his head is going to exhibit different responses than an amped-up meth-head.
Reflexive responses are hardwired responses to stimuli. Ever had your ophthalmic pressure tested by that little machine that blows a puff of air into your wide-open eye? Guess what: everybody blinks nanoseconds after that puff hits the eyeball. Likewise, perspiration is pretty much hardwired. Most of the biological responses in the startle response are hardwired, like vasoconstriction, and a change in blood pressure and respiration.
That "most" qualification of the important startle response brings me to "instinctive responses." The best lead-in here might be what we learned in high school about Pavlov and his salivating dogs.
Basically, there are three components to learning: it's due to experience with the environment (it doesn't just happen spontaneously); it's a change in behavior in the context of environment; and it's relatively long-term (something imitated once and forgotten a few seconds later is not learned).
And there are two broad categories of learning: Respondent Learning (the most basic stimulus-response stuff) and Operant Learning (most of what we humans think of as learning: volitional, cognitive stuff).
Pavlov's dogs, who were transitioned from salivating over meat powder to salivating at the sound of a bell, were working in Respondent Learning. They would still salivate at the presence of the meat (a "reflexive response"), but had learned (been conditioned) to also salivate at the bell (a trained "instinctive response").
While modifying a reflexive response can be very difficult to impossible, the next level, instinctive responses, can be modified through conditioning and habituation. And I'm of the opinion that the most effective techniques (for want of a better word) to learn at this level are those that least contradict the untrained response.
Best example I can use here is probably the startle response that occurs with a quick, unexpected movement near the face. If we hit Youtube and play back the idiot Iraqi journalist throwing the first shoe at President Bush, we'll see the President demonstrate the startle response: his legs and back flexed; the muscles in his arms contracted, raising them toward his face; he blinked; his neck flexed and he ducked his head away from the stimulus.
If you observe experienced boxers and street fighters, their startle response looks very similar with a few important exceptions: their response will be to lower the center of gravity even more, maintain balance rather than bob the head too far away, and the instinctive contraction of the arms will be exaggerated with the hands brought up higher to cover the face and head.
Contrast that to my first year studying Shotokan karate, 1967, where much of what I was taught was static stances, blocks, and strikes. I was trying to hardwire my instinctive responses in a manner that contradicted my untrained responses. Rather than learning to take the best possible advantage of the automatic response to dynamically move and cover, I was trying to swim upstream and condition myself to keep my torso erect, head up, and meet the incoming stimulus with a specific block. (A total aside, but during those same years I was also studying Filipino arnis, which was more pragmatic and less regimented; doing both at the same time caused me difficulties in advancing in either...but in the end I think I learned more than had I stuck with only one.)
This type of Respondent Learning is happening at very base levels. There's no, "If he turns to his left, I'll counter by intercepting with a right
soto uke and counter with a reverse punch." No thinking three chess moves ahead.
Putting this in terms of gun handling, without going into detail, that's why I think methods like the classic Speed Rock are inferior to techniques developed by guys like John Holschen, techniques that don't "fight" against the natural, untrained responses.
That's why I believe it's very important for people who are serious about their training to carefully seek out highly qualified instruction early: lay the proper groundwork so "bad" habits don't have to be broken later.
Elements of habituation come in at these lower learning levels, also. Habituation can be both a good thing and a bad thing.
For example, you don't want to startle yourself with your own gunfire. Watch the first
Lethal Weapon again, and pay attention to the scene at the indoor police range where Danny Glover puts a round right in the middle of the target's "head," then super-shooter Mel Gibson runs the target all the way to the back of the range and proceeds to add bullet-hole eyes and a smile to Glover's center-shot nose. Thing is, the "super-shooter" was flinching like crazy with each round he fired. Not a good thing.
Something kinda fascinating is that habituation, when dealing with reflexive and instinctive responses, is quite stimulus specific. You can be acclimated to one type of loud noise, like gunfire, but still susceptible to an acoustic startle response (ASR) at the sound of a door slamming. (Another interesting aside which again illustrates that individuals respond differently: studies have shown that chronic cocaine use greatly diminishes the reaction to ASR, and that effect continues even after use has been discontinued.)
Habituation is one explanation why people in combat or repeated life-threatening scenarios find their physiological reactions changing.
Last up is "trained response": Operant Learning. This is what we normally associate with instruction and learning. And just as the lines blur a bit between reflexive and instinctive responses, I think they can blur between instinctive and trained.
Through proper repetition over time, an individual can get to the point where some simpler elements of cognitive training can be internalized and executed at near-instinctive levels, requiring virtually no conscious thought. Some fundamentals of gun handling fall into this category, things like your combat drawstroke, reloads, and basic malfunction clearance. But that's a different discussion.
And if this wasn't long-winded enough, a final point to consider. In a conflict situation, you aren't the only one experiencing reflexive and instinctive responses. The bad guys do, too. So understanding these physiological and autonomic responses is important not only so that you might better manage your own reaction, but it's important food for your OODA Loop.