Posting this, mainly because I have yet to post in a "bear defense thread".
I guess that until humans learn to speak "bear", we will really never know what the exact motives of any bear (or other wild animal) really are.
I think it all depends on what is happening. For instance:
Momma Grizz and some cubs ---- probably means she is going to charge you to see if you are a threat. If you run, well, you must be guilty and she is going to whup your a$$ to make sure you are not a continued threat. Once the threat is neutralized (ie you're playing dead) she will leave. If you don't run, she might just bluff charge to within feet of you and not make contact. She'll probably be barking and vigorously chomping her jaws together. She might be making tight pacing circles, she's saying, I'm a mean mother-f....and don't mess with me.
Stand your ground and slowly back away with each repeat charge. If she makes contact, she's serious and you better pray and play dead.
Black bear and cubs ---- perhaps the same response, with the exception that I am unaware of bluff charges as a typical black bear response.
Single Grizz that you surprised, probably defending against what it deems to be a threat (or protecting a kill) - the best defense is a strong offense, right?...so she is going to whup your ass if you run. If you stand and are calm, you might make it out without contact.
Black bear out of no where fast, probably hungry because they seldom bluff charge and try to scare away threats. They run instead....not always, but generally.
Any bear at night - fight for your life.
Of course there are exceptions - no all mighty governing rule for the wild animals we encounter, humans included.
I think that people forget that if a larger grizzly really wanted to kill you, you would be dead. With a black bear, you might stand a chance of fighting back if you are lucky. Again, size matters. 200lb bear vs 500lb bear.
Am I an "expert"? No. But I have been present when a black bear scratched a friend at night (scary, very scary 18 stitches in the forehead and a nearly removed eye) and I have chased wounded black bears in the bush. One little 28" high, 135lb black bear took two 30-06 rounds and two 12 ga. slugs at a distance less than 40 feet (yes feet) before turning and running away 50 yards into the bush. First rifle round broke the shoulder, second round was a gut shot (scoped rifle in tight bush), first slug hit middle dead center, second slug hit high on body cavity and thru lungs. (all while the bear when absolutely ape sh_t, rolling, tearing trees, screaming)....now, you tell me how your little backpacker pistol is going to stop a 600lb pissed off grizzly? - not to mention a 1500 lb monster.
This turned into a rant, sorry. I just think people over-estimate their marksmanship under stress, it always come up on these forums that carrying the gun is the answer, but seldom do people really see that situational awareness is more important. Know your bears, and understand what "typically" makes them do what they do....I think that information is better than any .44
10 cents worth.
D
PS - IBTL