The
Freeze, Flight or Fight response is hard-wired into the general psyche of humans from time immemorial.
Getting past the
Freeze reaction may not be something the mental makeup of some folks may easily permit, if at all. The thin veneer of civilization may be more easily lifted away to uncover the Lizard brain more easily than some folks might be willing to admit, though. One loud noise can do it for some folks. Others seem to go into 'brain-lock' and remain in
Freeze.
Training, especially if combined with experiential knowledge (especially successful experience), can help get some people get past the Freeze response.
However, there's also the
hormonal fear response that can pysiologically throw a wrench into the works. It can interfere with conscious thinking. (Look up the writings of Dave Grossman on the subject.) Again, relevant training can help 'inoculate' us to a degree, but the emotional background noise may be hard for some folks to ignore.
One of the things I learned early in my LE career was to not only be alert to potential primary threats, but to remain alert to changes in the non-threats around me.
Kind of like how what we think of as prey animals may recognize the presence of a predator animal, people may become uncomfortable and react to the presence of someone who makes them uncomfortable on a visceral level, even if they're only reacting on a subconscious level and don't (yet) really know what's causing them to react that way to someone else. Their unease may be recognizable before the cause of their unease is visible or apparent to us.
As an example, I find it helpful to seat myself in my cigar club so I can watch the group's reaction to anything coming through the door. Sometimes I'll sit facing the door, but that can come with its own potential disadvantage. If
you can immediately see something that trips your radar, whoever it is causing it can also immediately
see you, and
see your reaction/recognition.
One of my friends there is another retired cop, and he
always sits facing the front door. I've found that positioning myself to watch
his expression and body language is handy, especially if whomever is causing him to react sees his reaction, but
can't see me recognizing his reaction. They can't immediately see past seeing him reacting to them, which
gives me an extra moment to consider my reaction (tactic, movement, etc) before they may even recognize I'm aware of them. I'm
not using him as bait, but am merely taking advantage of his desire in a respectful way, which I can hopefully use to my benefit.
Just another part of the tactical awareness of moving through group environments in what Cooper liked to call Condition Yellow. Hunters do it, recognizing when some animals become spooked to something that isn't the hunter.
A book that may be of interest to some folks is
Left of Bang: How the Marine Corps' Combat Hunter Program Can Save Your Life
An article from several years ago.
Getting Left of Bang: The next level of tactical awareness