When do babies notice other babies?

[thepriviledge]

My nearly 6 month DS is very watchful, looks long and hard at adult faces etc and seems very engaged...but yesterday I was with two friends and their babies, and when we put him on the mat next to one of the babies, he didn't look at him or given him any attention. The other baby, only just 5 months, was turned and looking at my DS quite intently and put his hand out.

Just wondered whether my DS acted normally around another baby

It's quite normal for a baby to take no notice at all of other babies and children.
It's really interesting, almost as though babies are aware of who can help and care for them and who can't. Another baby can be of no benefit to them.
At only 5 or 6 months of age babies haven't really learned to play yet.
At around a year of age you'll find that he plays and enjoys the company of other children, but they'll still play in parallel rather than actually playing together. The only real interaction will be when one gets in the other's way or steals a toy. Then a fight or screaming will break out.
Children don't really start actually playing together and interacting in a proper way until they're about 2.