[Tursiops2]

In my experience (I encounter a lot of dogs on my walks), dogs that bound toward you, barking, with their ears and tails up, are not likely to attack; they're basically alerting other "pack members", i.e. their owners, to the presence of a stranger in the vicinity, and issuing you with a challenge: "are you friend or foe?"

The one to worry about is the one that makes a beeline towards you, silent, with ears, tail, and head down, and then circles you, snarling. That dog clearly sees you as a threat (to its owner, probably) and is dangerous.

In either case, as demicav says, avoid eye contact. In the former case, avoid any threatening actions, ignore the dog and continue on your way. In the latter case, stand still and turn your back on the dog, and wait for its owner to get it under control.

If you have satellite TV, and want to gain a genuine insight into dog psychology, I can recommend a program called "The Dog Whisperer". It's on various channels, and it's extremely interesting.

Hope this helps.

T2