As a very general rule, no. The extreme quest for food may bring bears in closer proximity to humans but unless the bears are food-conditioned, they should not necessarily equate us with a food source. Not us, per se, as in there's a human to eat, but there's a human, they probably have some food that I can abscond with. As
@Absarokanaut said, their first reaction should be to run away, unless it's a sow protecting cubs and you have approached within their defensible personal space unknowingly, aka a surprise encounter. Fifty yards is a general distance within which a grizzly is more likely to charge but behaviors are so plastic, that distance can vary a lot.
Now, from what I saw from my 2 visits to the Yellowstone region this summer and fall, the berry crop was a near absolute failure in the GYE. This means that the bears (black and griz) will be ranging much wider to find calories and many will likely be a lot bolder in their quest. I found a lot of evidence of bears working
really hard for not a lot of calories. Those are hungry bears. You probably won't be seeing too many cubs-of-the-year next spring.
As long as you follow the general rules of bear safety ((keep your food unavailable, make plenty of noise to avoid surprise encounters, and pay attention to the local environment (rotting carcass smells; ravens, eagles, etc grouped together in a tree or trees; etc)), you should be fine. As poor condition as the females are likely in, many of them may have already headed for hibernation with the recent snows in the high country. Again a general rule, but sows with cubs are the primary ones to worry about as far as defensive attacks are concerned.
Hope that helps. It's a really complex topic but the basics apply most of the time.
