Electrophysiology reveals that intuitive physics guides visual tracking and working memory

Starting in early infancy, our perception and predictions are rooted in strong expectations about the behavior of everyday objects. These intuitive physics expectations have been demonstrated in numerous behavioral experiments, showing that even pre-verbal infants are surprised when something impossible happens (e.g., when objects magically appear or disappear). However, it remains unclear whether and how physical expectations shape different aspects of moment-by-moment online visual scene processing, unrelated to explicit physical reasoning. In two EEG experiments, people watched short videos like those used in behavioral studies with adults and infants, and more recently in AI benchmarks. Objects moved on a stage, and were briefly hidden behind an occluder, with the scene either unfolding as expected, or violating object permanence (adding or removing an object). We measured the contralateral delay activity, an electrophysiological marker of online processing, to examine participants' working memory (WM) representations, as well as their ability to continuously track the objects in the scene. We found that both types of object permanence violation disrupted tracking, even though violations involved perceptually non-salient events (magical vanishing) or new objects that weren't previously tracked (magical creation). Physical violations caused WM to reset, i.e., to discard the original scene representation before it could recover and represent the updated number of items. Providing a physical explanation for the violations (a hole behind the occluder) restored object tracking, and we found evidence that WM continued to represent items that disappeared 'down the hole'. Our results show how intuitive physical expectations shape online representations, and form the basis of dynamic object tracking.