I agree with Corinna, dogs definatly think and have the ability to reason, I have seen WAY to many cases of this is ever believe otherwise. Perky tricks the other dogs when she wants something all to herself. Happy does too, I have seen her fake out the other dogs so many times, then when she suceeds she picks a spot near the dog she faked out sit down and grin at them, its hilarious. Perky like to get even with my mom when she is annoyed

but I would agree with crating your dog to solve this issue.