Effect of velocity on judgments of relative mass.

Research indicates that people can accurately judge the relative mass of colliding objects, i.e., which is heavier, if the collisions viewed involve actual physical objects. This study explored whether such judgements are affected by the image velocity of the colliding objects. Videotaped collisions involving different screen velocities were shown to observers. The accuracy of judgments of collision decreased significantly at slower velocities. A velocity-threshold hypothesis is offered as a possible account for this finding.