I’m going to post this in response to a couple of requests on the OODA (observe, orient, decide, act) Loop. There are some I know have/can explain this with greater precision than I but I’ll get the post going and they’re welcome to add, subtract, multiply or divide. First of all, someone tried to tell me the other day that the “LOOP” is solely linear and in-order. (No, no it’s not. Webster’s can help greatly with this) Context is imperative in the processing ability of the orient and decide phases of the loop. The more context available, the better the ability to process the level and type of threat and decide on A (a, not “the”) correct action, or no action, sometimes also a completely valid response, context-dependent. How we process internally is a combination of what I call/use as “I foresee” (or i4c): a mix of *intuition (from previous like experience of similar/relatable stimuli that transfers) and external stimuli including *congruence (what’s actually happening vs. your perception/accurate previous experience, etc. – are you over- or under-reacting), *culture (prevalent here for me, what the cultural norm is in one place is not in another and will stand out), *context (the 5Ws and appropriation of the 5 – do they fit into the given context – person, activity/action, location, time-of-day, reason) and *clusters (usually more than one signal presents itself to give you growing information to validate course of action)

These can be pre-influenced internally by a number of things as well: religion, upbringing, previous training, experience, belief structure, etc. and processing speed is based on the above)
Now, this all is great outside of the ambush or surprise attack where situational/environmental awareness is a hugely beneficial tool. In my estimation, this circumstance has one fall back on an instinctive combination of proper/correct previous training and innate survival response coupled with self-control and the ability to push forward from the point-of-reference, which far too few work….knife already in stomach, on-ground being kicked, having taken a big shot, etc. etc. etc. (Another post but keeping it simple for the sake of post-length)
Though complex, all this takes a far shorter time than it takes to explain to someone else. As they’re infinite, I’m not going to delve into specific examples. As usual, the more this is researched and understood, the faster one comes to understand what happens cognitively.