An intuitive understanding of physical objects and events is critical for successfully interacting with the world. Does the brain achieve this understanding by running simulations in a mental physics engine, which represents variables such as force and mass, or by analyzing patterns of motion without encoding underlying physical quantities? To investigate, we scanned participants with fMRI while they viewed videos of objects interacting in scenarios indicating their mass. Decoding analyses in brain regions previously implicated in intuitive physical inference revealed mass representations that generalized across variations in scenario, material, friction, and motion energy. These invariant representations were found during tasks without action planning, and tasks focusing on an orthogonal dimension (object color). Our results support an account of physical reasoning where abstract physical variables serve as inputs to a forward model of dynamics, akin to a physics engine, in parietal and frontal cortex.
- Nancy Kanwisher
- Sarah Schwettmann
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: All participants provided informed consent before participation. The Massachusetts Institute of Technology Institutional Review Board approved all experimental protocols (protocol number: 0403000096).
- Thomas Yeo, National University of Singapore, Singapore
- Received: March 6, 2019
- Accepted: December 10, 2019
- Accepted Manuscript published: December 17, 2019 (version 1)
© 2019, Schwettmann et al.
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