The short answer: It’s fun! But there’s important learning going on behind your hands or that blanket. Peekaboo is a simple game that develops an understanding of the very sophisticated concept of object permanence. 

You can play this kind of hide-and-seek game with a younger baby, and he enjoys it because he’s always happy to see your face reappear. What a nice surprise! And until about 7 or 8 months old, it is a genuine surprise. Younger babies don’t think about things they can’t see right in front of them. The phrase “out of sight, out of mind” perfectly describes this earlier level of mental development. 

By around this time, though, your baby begins to understand that things he can’t see still exist. You hide your face behind a blanket, and although he can’t see you, he knows that you’re still there. This is a big step. He’s no longer uncurious or unconcerned about your disappearance. And the game becomes all the more exciting. 

Learning about the permanence of objects and people in the world doesn’t come as a sudden flash of insight; it’s a cognitive skill that develops gradually. That’s probably why peekaboo is such a source of delight. It helps your baby understand a key concept—and, even better, it involves you! Understanding that things continue to exist even when he can’t see them affects your baby in many ways. He knows that a favourite toy that has dropped from his crib is down there somewhere, even if he can’t see it, and he may whimper for it. And he knows that, when you leave the room, you’re still around—somewhere. 

Pop-up toys work on the same principle as peekaboo—now you don’t see it, now you do! You can build on the idea of object permanence by hiding a toy under a blanket. A younger baby will ignore it, but an 8-month-old knows that it’s still there and will work to uncover the toy. Later, your baby will love games that encourage him to look in slightly less obvious places for hidden toys, such as under one of several baskets or beneath a jumble of blankets.