WASHINGTON (AP) _ When a toy falls behind the chair has it vanished forever? The answer is no, of course, and a new study indicates babies can figure that out at a few months of age simply by watching.
Scott Johnson of New York University led a team that studied babies in an effort to determine when and how they realize that a rolling ball that disappears behind something is just playing peek-a-boo, and is going to reappear on the other side.
``What's truly amazing is how rapidly they're able to pick up these concepts,'' Johnson, who studied babies aged four months and six months, said in a statement.
Experts have been divided over how babies learn about the behavior of objects. Some believe they learn by handling objects. Others, noting that some children seem to understand how objects work before they can handle them, argue that this understanding is innate.
The new findings, reported in this week's online issue of Proceedings of the National Academy of Science, indicate that babies can learn simply by watching.
The researchers tested 48 four-month-olds and 32 six-month-olds.
Each infant sat in a parent's lap and watched a 32-inch computer screen showing a moving ball. The babies' eye movements were tracked and recorded by a special camera.
Four-month-old infants shown a ball that was obscured as it passed the center of the screen had little ability to anticipate where or if it would reappear.
Then they were shown the ball moving back and forth without being hidden at any time.
After just two minutes of watching, the ball was again hidden in the middle of the screen. Most infants had learned to expect the ball to reappear, the researchers said.
When the team tested six-month-olds they found that many already grasped the idea that the ball would reappear, suggesting that they had already learned from real-world experience viewing objects that roll behind something.