I did a little research into this matter and discovered experts who say to never, NEVER play dead for a bear who's attacking you - or you will be!

Apparently on the rare occasion when a grizzly bear - or any other type of bear - decides to prey on a human being, they're going to be stealthily hunting with the intent to kill and eat. You likely won't hear them coming, and any attempts to play dead will just get you ripped to shreds all the faster. This expert here - who is the author of many bear handling wilderness books - insists that you should always fight back against a bear attack at any cost and in any way possible. It's the only chance you have.

The exception to the rule?

If a bear is not on the attack, but is being defensive. If you've come too near a mama's cubs and she's charging at you defensively, then it's best to play dead. Odds are she won't even touch you - she doesn't want your meat, she wants you to leave her cubs alone!