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Breakthroughs

How Babies Learn

By Andrea Appleton
Drawing of Lisa Feigenson
Lisa Feigenson is a professor of psychology and co-director of the Johns Hopkins Laboratory for Child Development.

A ball rolls through a solid wall. Another is released in midair and hovers there, unassisted. Decades of research have shown that babies react much as adults do to magic tricks like these. They do a double take, and then they pay closer attention. Infants as young as 2 or 3 months tend to look longer at seemingly impossible events. Hundreds of studies on infant cognition have relied on this convenient behavior, known as the looking-time measure. Yet until recently, researchers had not asked why babies focus for more time on something surprising.

“No one had ever explicitly asked, ‘So what? Why do babies produce this behavior that’s extremely systematic?’” says Aimee Stahl, a former graduate student of the Johns Hopkins Department of Psychological and Brain Sciences. She and Lisa Feigenson, co-director of the Johns Hopkins Laboratory for Child Development, wondered if the act of being surprised might help babies zero in on a learning opportunity.

Babies, by definition, have a lot to learn, and they are under constant bombardment by new stimuli. How do they decide what to concentrate on and what to ignore? “The number of possible things that we could be learning at any given moment is literally infinite,” Feigenson says. “You have to carve that learning space down somehow.” Perhaps, the researchers thought, surprise somehow helps babies decide what to focus on.

Feigenson and Stahl conducted a study, published this past April in Science, proving just that hypothesis. Eleven-month-old babies shown magic tricks (such as a ball hovering in midair) subsequently learned about the object better than babies who were shown predict-able events (such as a ball falling to the ground upon release).

Babies who had seen  an object hover in  midair were more likely to repeatedly drop that object, as if testing its reaction to gravity. 

The study involved several experiments. In the first, one group of babies was shown a predictable event, like a ball rolling down a ramp, hitting a wall, and stopping. The other group, through sleight of hand, was shown something related but impossible, like a ball rolling down a ramp and seemingly passing through a solid wall. Then both groups were taught something about the object, for instance that the ball made a squeaking noise. The babies shown the magic trick were more likely to absorb that information than were those who saw the mundane event. Further experiments revealed that the surprised infants were primed not only to learn but to learn specifically about the particular object that had defied their expectations.

“Seeing something that violates your expectations might signal a special opportunity for you to update or revise the knowledge that you have,” says Stahl, who was the paper’s lead author. 

The researchers then tested whether babies would prefer to play with objects that had surprised them. When they gave babies that object alongside a new, unrelated toy, they found babies did indeed prefer the object that had confounded their expectations. What happened next is the most provocative finding of all: Babies who had seen an object hover in midair were more likely to repeatedly drop that object, as if testing its reaction to gravity. Those who had seen an object pass through a solid wall tended to bang it on a highchair afterward, as if testing its solidity. The babies, it seems, were conducting trials of their own. 

“It’s the same thing scientists do,” Feigenson says.“When I run an experiment and it doesn’t turn out the way I thought, it leads me to want to dig deeper to understand why I was wrong.”

Their findings suggest that infant cognition is even richer than we imagined. “Not only do babies have really sophisticated knowledge about the world, which we have known for a little while now, [but] our results show that they then can use that knowledge to figure out what they should learn about in the future,” Stahl says. 

The lab’s related studies with older children are yet to be published, but Feigenson says the results could also have implications for education. For instance, she says, “if you get children to generate predictions and those predictions are wrong, that may actually be an incredibly useful learning opportunity.”

For now, parents should give babies dropping Cheerios off their highchairs for the umpteenth time some credit. Perhaps they’re testing a hypothesis. 

Illustration of a baby reaching for a red ball in the air
Image above by Francesco Bongiorni; Feigenson drawing by Caroline Andrieu
Infants as young as 2 months tend to look longer at seemingly impossible events, but until recently, no one had asked why babies focus for more time on something surprising. A new study shows that babies conduct their own experiments and that seeing something novel signals an opportunity to learn.

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