Found whilst gratuitously surfing http://www.nps.gov/bela/html/morebear.html
The following is an extract of the advice given if you see a
bear. The principle is: avoid being in contact with bears if
you can. Give the bear every opportunity to avoid you. If you
do encounter a bear at close distance, remain calm. Attacks
are rare. Chances are, you are not in danger – most bears are
interested only in protecting food, cubs or their “personal
space.” Once the threat is removed, they will move on.
Remember the following:

Identify Yourself – Let the bear know you are
human. Talk to the bear in a normal voice. Wave your
arms and help the bear recognize you. If a bear cannot tell
what you are, it may come closer or stand on its hind legs to
get a better look or smell. A standing bear is usually
curious, not threatening. You may try to back away slowly
diagonally, but if the bear follows, stop and hold
your ground.

Don’t Run – You can’t outrun a bear. They have been
clocked at speeds up to 35 mph, and like dogs, they will
chase fleeing animals. Bears often make bluff charges,
sometimes to within 10 feet of their adversary, without
making contact. Continue waving your arms and talking to the
bear. If the bear gets too close, raise your voice and be
more aggressive. Bang pots and pans and use noisemakers.
Never imitate bear sounds or make a high-pitched squeal.

Surrender – If a brown bear actually touches you, fall
to the ground and play dead. Lie flat on your stomach, or
curl up in a ball with your hands behind your neck. Typically
a brown bear will break off its attack once it feels the
threat has been eliminated. Remain motionless for as long as
possible. If you move, a brown bear may return and renew its
attack and you must again play dead. If you are attacked by a
black bear, fight back vigorously.