Ever since I got Oliver at three months old, he has been "forgetful" about where people are in the house. We live in a three story house, and most of his time is spent on the second floor. Well, if someone goes upstairs for ten minutes, when they come back down he barks at them like they're a complete stranger even when they get completely in the room. Once the person says something and he recognizes the voice, he calms down. Before that, he barks and his hackles are raised. If he can see strangers coming, he is better.
FWIW - Nothing traumatic has ever happened in my house with strangers. I instruct all visitors to ignore him until he is calm, and then they can calmly greet him and give him treats.
Is there anything I can do to turn the tide on this? I'm reading it as a fear reaction and I certainly don't want this to progress into fear biting or other problematic behaviors.