“All this can suddenly change”
“Mom? Isn’t that that milk lady? Yeah I think she’s pretty swell, I guess.” In the first six months of development, babies definitely show preferences for familiar faces and smells, and can certainly be comforted in mom’s (and dad’s) embrace. But as soon as you leave the room they seem to forget that their favourite person isn’t close by. Out of sight, out of mind.
All this can suddenly change somewhere between 8 and 12 months, when separation anxiety sets in. See, from about the fifth month on, babies start developing a skill called object permanence – they know that an object still exists even if they can’t see it. By approximately eight months most babies have mastered this skill.