Physics and mind are two major causes of motion. In a leash-chasing display, a disc (“sheep") is being chased by another disc (“wolf"), which is physically constrained by a leash attached to a third disc (“master"). A number of interesting motions can emerge from this simple system, such as a wolf being dragged away from its target. Therefore, it is important for vision to jointly infer a physics-mind combination that can best explain the motions. Here we reported two discoveries from studying this display to support this theory. First, an intuitive physical system like a leash can greatly lessen the detrimental effects of spatial deviation and the diminishing objecthood on perceived chasing, strengthening its robustness. Second, a mutual dependency exists between physics and mind, where disrupting one will inevitably result in an impaired perception on the other. These results collectively support a joint perception of physics and mind
