I got to interact with a baby today, which is unusual for me since I don't
know any babies socially. One thing I noticed is that the baby would often
stare at people who were doing the most innocuous things, like eating or
chatting or walking around. While I was in a large group and there was
always at least one, often more, people interacting directly with the baby,
he would often stop and stare at other, unrelated goings-on.

I have a theory about this. I think the baby is used to people looking at
him and making faces and saying "Hiiiiiii!" in that high-pitched voice
everyone uses to talk to babies. I think he stares at other things to see
what the grown-ups do when there's no baby around. This must be how kids
learn how life works, otherwise all everyone would know how to do is stare
people in the face and say "Hiiiiiiiiiiiiiii!"