No, because the dog could smell and hear the human, just like they could smell the treat.

Haha, fair enough.

It's possible the human ceases to exist once the treat is present. The same thing happens to me when there's dessert next to the salad.

Frankly, as a parent of three I'm not at all convinced that human infants lack object permanence, much less adult dogs. I've never observed anything in my infants that would indicate they lost track of something's existence, and I've seen plenty of things that suggest the opposite.

See also the section of that article entitled "Contradicting evidence".

As a parent also, I think it simply varies from child to child. There is a point in time between vision developing and object permanence being learned where peek-a-boo is absolutely magic.

Peek-a-boo is a ton of fun with infants but I don't buy the explanation that it has to do with object permanence. At the same stage where peek-a-boo is hilarious my kids have also each been perfectly capable of watching me hide something and then going looking for it.

OT but maybe peekaboo works on the emotional tension and release of potential threats being revealed as friendly faces.

Or maybe it's just a fun game.