My understanding is that if you struggle and scream the bears instinct is to try and kill you (like biting you in the neck...hard). If you play dead (and this is still considered the right thing to do with grizzly bears) they are more likely to leave you alone for the time being...leaving you to come back when they are hungry...or at drag you into the bush to snack on later. Only if you're sure the bear is trying to eat you right then and there are you supposed to fight as the alternative is to let yourself be eaten. I imagine deciding where that line is would be difficult with 1000lbs of bear on top of you...I hope I'm never in that position or anywhere's close to it.

Something I just learned recently however is that if a black bear is doing the same thing (namely trying to eat you) you should treat it like a cougar attack and immediately fight like hell with everything you have. The behavior of a Black bear vs a Grizzly is quite different. Around here Black Bears aren't as 'lazy' as Grizzlies are and will go after a person with a lot less motivation (Grizzlies tend to favor whatever action gets them the most food for the least energy expended). I also wonder if they suggest this behavior because it's technically easier to fight of a Black than a Griz...though I'd not want to do either. Black bears get BIG around here.

That being said I don't go out without OC spray AND a big knife at the ready. There are too many unpredictable factors that you just can't be completely ready for. Just the other day I was talking to a friend of mine who's a retired forestry worker. He recalled a story about a Grizzly which attacked a few of his crew for no reason. They took it down with shotguns but it turns out it had been shot 2 days previous and the hunter who was 'defending himself' didn't finish the job. Few things more dangerous than an injured, pissed off Grizzly.