Show an infant something unusual or surprising—say, reveal a toy that had been hidden—and the baby will perk up and pay attention. A new study investigates why this is so and finds evidence that young children are wired to focus on the unexpected to learn how the physical world works.

Aimee Stahl, a Ph.D. candidate in psychology at Johns Hopkins University, and her colleagues studied a group of 110 11-month-old babies. Some of the babies were shown confusing vignettes: they saw a toy seemingly pass through a wall, defy gravity or appear in an unexpected place. Other babies observed a toy that behaved normally. Then the researchers introduced a new toy to all the babies while demonstrating that the first one made noise. Now faced with two toys, the babies who observed only ordinary toys were equally enamored of both—but the babies who saw the first toy do strange things paid more attention to it and ignored the new one.

Next the babies were given a chance to play with the toys that seemed to defy logic. The experimenters found that the babies who saw the toy pass through a wall were more likely to bang it on the table, but those who saw the toy defy gravity liked dropping it on the ground—perhaps in an attempt to understand more about the toy's baffling physical properties.

The findings, published in Science, suggest that “babies have predictions about the world that they can use to guide their behavior, as well as what and how they learn,” Stahl explains. Granted, objects in the real world do not often defy gravity. But Stahl suspects that babies also learn from more typical unexpected events, such as changes of routine and hearing new verbal phrases, and she is designing experiments to test this idea. “Our hunch is that these kinds of improbable events would also influence learning,” she says.