Your Brain Has A 'Physics Engine' And Scientists Have Located It

The brain knows instinctively how to predict when accidents are about to happen.

10/08/2016 12:26 AM AEST | Updated 11/08/2016 4:12 AM AEST

If you’ve never been particularly good at physics in school, it might make you feel better to know that at the very least, your brain comes with a built-in “physics engine.”

In a new study published Monday in Proceedings of the National Academy of Sciences, scientists have located a set of brain areas that become active when people predict how objects move in the world based on physical laws.

Granted, your physics intuition is not going to help you very much in solving textbook physics problems involving quantum mechanics or planetary motion. But it does something arguably more important: by instantly carrying out physics calculations, it allows you to deal with the physical world in daily life in numerous ways—from walking more carefully on slippery ground on a rainy day to catching a falling stack of dishes to filling up a plastic bag with just enough items so it doesn’t break.

It’s also what makes you really nervous when looking at this photo:

Vstock LLC/Getty

And what helps you pick just the right fruit from the pile without causing an embarrassing scene at the grocery store:

Jason Fischer

Oh, and it helps you play Jenga well.

“It’s hard to appreciate just what a role physical reasoning plays in your daily life until you start paying attention to the things that you do,” Jason Fischer, a cognitive scientist at Johns Hopkins University and co-author of the study, told The Huffington Post.

To find where these physics simulations run in the brain, Fischer and his colleagues at MIT asked 12 people to watch a series of videos of an unsteady tower of blocks. In some trials the participants had to pay attention to just the visual information and answer how many blocks were blue and how many were yellow. In other trials, they had to predict which way the blocks would fall if the tower collapsed.

Here you can watch an example of this game and test your own physical intuitions:

When the participants tried to predict the unfolding of physical events, several brain regions activated on the brain scans. Additional experiments revealed the same brain areas light up on the scan even when people passively watch video that involves a lot of physical actions such as rolling and colliding objects.

These regions were found in the premotor cortex and the supplementary motor area, the areas thought to be involved in planning actions such as reaching to grab objects.  

Jason Fischer/Johns Hopkins University

The findings suggest that physics intuition and action planning are “intimately linked in the brain,” Fischer said in a press release. “We believe this might be because infants learn physics models of the world as they hone their motor skills, handling objects to learn how they behave.”

Previous research probing physics intuition in infants has revealed that babies follow a systematic time course during the first year of life in which they acquire an understanding about different kinds of physical relationships in the world. 

Take two simple objects, for example. First babies learn the objects have to be touching each other to have any physical effects on one another. A bit after that they learn that an object has to be actually on top of another to be supported by it. Then they learn about the importance of an object’s center of mass and other properties, further deepening their implicit knowledge of physical laws.

A lot of other animals, too, likely have sophisticated physics engines.

“From a standpoint of survival it might be even more critical to animals that it is to us,” Fischer said. “Animals need to know what surfaces they can jump onto that can support them. They know they can’t walk on water and have to go around it. Animals are really good at these kinds of basic stuff.”

If you have any doubts about that, just watch the Jenga cat:

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