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Brainiac babies

Infant studies indicate 'intuitive physics' knowledge is present soon after birth

Northwestern University

EVANSTON, Ill. -- A Northwestern University study has found that the evidence for intuitive physics occurs in infants as young as two months - the earliest age at which testing can occur.

Intuitive physics includes skills that adults use all the time. For example, when a glass of milk falls off the table, a person might try to catch the cup, but they are not likely to try to catch the milk that spills out. The person doesn't have to consciously think about what to do because the brain processes the information and the person simply reacts.

The majority of an adult's everyday interactions with the world are automatic, and researchers believe infants have the same ability to form expectations, predicting the behavior of objects and substances with which they interact.

But the world is not made up of objects alone, and Northwestern researchers looked at whether babies can distinguish between objects that can be held or thrown versus substances such as liquids that can flow and are drinkable.

According to a review of literature, infants show an understanding that unsupported objects will fall and that hidden objects do not cease to exist. Scientific testing also has shown that by five months, infants have an expectation that non-cohesive substances like sand or water are not solid.

"I think liquid is the best example of a non object that you interact with --- a baby has to drink liquid every single day," said lead author Susan J. Hespos, associate professor of psychology at Northwestern's Weinberg College of Arts and Sciences. "It's a universal experience with milk or water. We did studies on whether babies expected water to pour or tumble from an upended cup. By five months of age, babies expect both water and sand to pour, so we have clear evidence that this type of physical knowledge is available early in development."

While the intuitive physics knowledge is believed to be present at birth, co-author Kristy vanMarle, assistant professor of psychology at the University of Missouri, believes parents can assist skill development through normal interaction, such as playing and talking with the child and encouraging him or her to interact with objects.

"Natural interaction with the child, such as talking to hi or her, playing peek-a-boo and allowing him or her to handle safe objects, is the best method for child development," vanMarle said. "Natural interaction with the parent and objects in the world gives the child all the input that evolution has prepared the child to seek, accept and use to develop intuitive physics."


The study, "Physics for Infants: Characterizing the Origins of Knowledge About Objects, Substances, and Number," is published in the January issue of WIREs Cognitive Science.

(Source contact: Susan J. Hespos, email:; 847-467-1394)


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