Visual perception of bouncing and jumping

We systematically explored the degree of consistency between the physical and the perceptual laws of the events of bouncing and jumping. Several parameters of the animation were manipulated across four experiments. Participants were presented with animations showing a small disk moving vertically back and forth repeatedly along the vertical axis of the screen, and had to indicate if the display showed the bounce of a physical inanimate object, the animated motion of a living creature, or an undefined motion. The results revealed that uniform acceleration tended to enhance visual impressions of a physical bounce, although this effect was more evident in the case of one bouncing cycle than in the case of three bouncing cycles, and for values of acceleration much smaller than 9.81 m/s2; moreover, physical bounce impressions were more likely for values of C (coefficient of restitution) < 1, and by delays at the impact in the range 0-30 ms. The animated jump impressions were more likely for values of C > 1 and by delays between 90-150 ms. Interestingly, neither physical bounces nor animated jumps were affected by the presence or the absence of a bouncing surface. Overall, the results indicate that visual impressions of physical bounce and animated jump strongly depend on kinematics, can be visually perceived in a relatively direct and automatic manner, and are largely independent of the corresponding physical laws, consistently with the Gestalt-theoretic account of event perception.