Baby's Brain in Week 45
At this age, your child not only knows that objects continue to exist when out of sight, and that a partially covered item really does exist in its entirety under the cover, but she now also understands that when an object is completely covered, the shape of the covering reveals something about the object beneath it. During a game of hide and seek, hide behind a curtain and your child will easily find you: The shape of your body under the curtain gives you away to your ever-smarter baby.
What the Research Shows
In follow-up research to the object permanence studies, scientists first laid a piece of cloth flat on a table. Then they pushed a solid screen in front of the cloth (perpendicular to the table) so that the babies couldn't see the cloth or the researchers, who then set a teddy bear next to the cloth. As soon as they did so, they pulled the screen away. The nine-month-old babies were eager to see what had been under the cloth, so they were perplexed upon seeing the bear: How could that bear have appeared from under the cloth, which had been laying flat? The babies knew that for the bear to appear, the cloth would have had a bear-shaped mass under it.
Then the researchers covered a small bear with a cloth. The babies could only see the cloth and that something was under it. The researchers set the screen in front of the cloth-covered bear, secretly removed the small bear, and put a large bear next to the cloth. The babies again were eager to see what had been hiding under the cloth. What the babies saw was a bear too big for the cloth which had been covering the small bear. This time the babies, however, didn't mind. It was impossible for the small cloth to have covered up the large bear, but at nine months the babies didn't notice this impossibility.
It's not until 12 months that babies know that the event is impossible—that is, to see a large bear appear when only a small one had been under the cloth—and look perplexed. By this age, babies know that a covering takes on the shape of the item underneath it, and that the size of the shape determines the size of the object once it's revealed.