Thomas Brewitt¹ (), RT Pramod¹, Vivian Paulun², Nancy Kanwisher¹; ¹MIT, ²University of Wisconsin-Madison

Previous studies have identified a fronto-parietal Physics Network (PN) that is preferentially activated when people view or engage in physical reasoning. These studies have used only visual stimuli, but our intuitive understanding of physics is not limited to vision alone: think glass clinking or water splashing. We previously showed that the PN doesn’t respond when subjects passively listen to physics-related sounds. Here we tested this finding in PN further when subjects are encouraged to attend to physical properties of our stimuli through an “odd-one-out” task. We gathered short (3-sec) naturalistic audio and video clips of physical and social conditions, each condition having 3 subconditions: collisions, flowing, and spinning for the physical condition, and speech, social interactions, and nonverbal sounds (crying, laughing, etc.) for the social condition. Stimuli were presented in a 2 (modality) x 6 (subcondition) blocked fMRI design, with interleaved fixation baseline blocks, while subjects (N=5) performed an “odd-one-out” task requiring them to identify a non-matching stimulus. The same participants also performed two additional experiments (one visual, one auditory) in which the same stimuli were presented along with blocks of their scrambled versions that were not recognizable but retained low-level features. The independently localized PN showed a stronger response to physical videos than social videos (p<0.005). All auditory conditions produced a PN response near baseline. The PN showed a stronger response to intact than scrambled physical videos (p<0.05). Remaining conditions responded near baseline. These findings show that the PN doesn’t respond preferentially to auditory physical events (compared to auditory social or scrambled physical events, or to baseline) even when the task requires discriminating event types. These findings suggest that PN doesn’t engage in multimodal processing of physical information, and that intuitive physical information from auditory cues may be processed elsewhere in the brain.