Visual Perception of Relative Mass in Dynamic Events

Two experiments are reported which examine how the dynamic property of relative mass in collision events is specified by kinematic properties of a visual motion display. In most cases observers are accurate at detecting the 'heavier' of two objects, although they do not take advantage of the completely general optic information that is available. Instead, they rely on limited information that breaks down at extreme values of elasticity and relative initial velocity. In addition, observers appear to utilize different information for relative mass with different types of collisions. It is suggested that reliance on such limited information may be appropriate for perceivers operating in the restricted context of a terrestrial environment.