Most of what most of us grow up learning about black bears is wrong. They are not the cuddly balls of fur that some people would have us believe, but neither are they the crazed killers that others imagine them to be. Bears may attack a human being if they feel threatened, or for other reasons that only a bear would know or be able to appreciate, but they rarely view people as food, and they are far more likely to run from you than attack you, whatever the circumstances.
Most bear attacks are initiated by caged or pet bears whose natural instincts have been changed by captivity, and whose environments are unnatural. In the wild, most bear attacks have occurred in national or state forests, which are artificial environments in which bears may have come to associate people with food, either from the direct feeding of bears or careless camping habits.
Each black bear has a comfort zone that is individual to the bear. This is an area around the bear in which it is unsafe to intrude. Entering the personal space of the bear will cause the animal to feel threatened, and may result in an attack. Even so, a black bear is more likely to retreat than to become aggresive. Perceived attacks are usually mock charges, designed to encourage an intruder to leave the personal space of the bear. Running from a mock charge may encourage the bear to continue pursuing the person, possibly resulting in a genuine attack, so running is not advised.
Bears often appear slow and cumbersome while walking but they are capable of speeds in excess of thirty miles an hour while running, which would allow the bear to easily outrun you if it wanted to. In short distances, a black bear can run uphill or downhill, climb trees, or swim at about the same speed, so it is best to retreat from a bear's personal space by backing away slowly.