yeah Dave , this is a tricky one, It sounds like typical alert barking. Your problem is whether to acknowledge it or not. If you have frequent people arriving in the apartment each night and at sleeping hours it can cause a lot of interuptions in your sleep . It's up to you to decide if you want to ignore all his warnings or not. If you do want to eliminate this alert barking you have to ignore it totally, ie, don't even move or breath lol. Your terminology is correct when you said "extinguish" the behavior. But be prepared he will probably bark louder to get your attention ,which is called an extinction burst. And that could pose another problem with waking up your fellow apartment dwellers. It's nice to acknowledge our dogs when they are warning us , but this one comes with some disadvantages. See how it goes. You'll have to be the judge.
Dave and Molly
Ian Dunbar was awarded the Outstanding Achievement Award from I.P.D.T.A. Here's a picture of me accepting the award on his behalf.
Member of IAABC ,International Association of Animal Behavior Consultants , Member of Pet Professional Guild