Sep 1 2016
Researchers have discovered the parts of the brain responsible for comprehending and computing real time physics calculations, which help us better understand the world around us. The research is coming out of a combined effort of Johns Hopkins Krieger School of Arts and Sciences and the Massachusetts Institute of Technology (MIT).
“We run physics simulations all the time to prepare us for when we need to act in the world,” said lead author Jason Fischer, an assistant professor of psychological and brain sciences in the Krieger School of Arts and Sciences, in a news release. “It is among the most important aspects of cognition for survival. But there has been almost no work done to identify and study the brain regions involved in this capability.”
The study was published in the journal Proceedings of the National Academy of Sciences.
The researchers out of Johns Hopkins and MIT conducted a series of fMRI experiments to try to engage the part of the brain responsible for making physics calculations. They recruited 12 subjects to look at a video of a Jenga tower and predict where the blocks would fall as well as if there were more yellow or blue blocks, while their brains were being monitored. Guessing the positions of the blocks was a physics question, while the color question was merely visual.
The second experiment had people look at a screen with two bouncing dots and had them predict the direction the dots would head, based on physics or social reasoning.
The researchers found that in both experiments, when the subjects tried to predict physical outcomes, the most responsive brain areas were the premotor cortex and the supplementary motor area. This is the brain’s action planning region. The article’s abstract describes this as the “physics engine” in the brain.
However, the functions of these regions of the brain are not exclusive to physical inferences or even to scene understanding. The function of these regions of the brain overlap with what is described as the “multiple demand” system, especially those engaged with action planning and tool use.
“Our findings suggest that physical intuition and action planning are intimately linked in the brain,” Fischer said in the news 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. Also, to reach out and grab something in the right place with the right amount of force, we need real-time physical understanding.”
For the last part of the experiment, the researchers asked the subjects to watch video clips, while their brains were being monitored. Some of the video clips included lots of physics content, others very little. They found that the more physics content in the video, the more the key regions in the brain were activated.
“The brain activity reflected the amount of physical content in a movie, even if people weren’t consciously paying attention to it,” Fischer said in the news release. “This suggests that we are making physical inferences all the time, even when we’re not even thinking about it.”
The results offer insights into disorders such as apraxia, a movement disorder caused by damage to the brain, in which someone has difficulty with motor planning to perform tasks or movements when asked. It’s possible people with damage to the motor areas also have trouble making physical judgments.
Knowing which parts of the brain are responsible for physics calculations could also help with robot design. A robot built with a physics model could navigate the world more fluidly.