Thinking & learning
Object permanence
Many babies — 8–12 months
Understanding that things still exist when hidden — why peekaboo and hide-the-toy suddenly delight them.
What’s happening
Understanding that things still exist even when hidden is why peekaboo suddenly gets a real reaction, and why they'll now look for a toy that rolled out of sight instead of losing interest. Before this clicks, 'out of sight' really does mean 'gone' to a baby — which is also part of why separations can suddenly feel harder around the same age.
How to support it
- Peekaboo and simple hide-the-toy games aren't just fun — they're direct practice for this exact skill.
- Narrate it: 'where did it go? there it is!' — the words reinforce what they're already figuring out.
- Hide a toy partially at first (with a corner sticking out) before hiding it completely — it's an easier version of the same puzzle.
When to ask your pediatrician
Looking for a dropped or hidden object is one of the CDC's checkpoints for 9 months. If your baby shows no interest in searching for something that's gone out of sight by around their first birthday, mention it at their next visit.
Often leads to pretend play
Where this comes from
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