The visual perception of relative mass from object collisions

Previous research has shown that observers can make reliable judgments about the relative mass of moving objects that collide in animated displays. One popular explanation of this is that observers' judgments are based on an internal model of Newtonian dynamics. An alternative explanation is that these judgments are based on measurable optical properties that are correlated with relative mass. To better understand this issue, the present investigation reanalyzed the data from three previous studies by Mitko and Fischer (2023), Sanborn et al. (2013), and Todd and Warren (1982), and it replicated an additional study by Hamrick et al. (2016). These new analyses demonstrate that observers' judgments of relative mass are most likely based on the post-collision optical velocities of objects without having to invoke an implausible mental representation of Newtonian dynamics as has been argued by several previous investigators.