Event dynamics were investigated as a determinant of the perceptual significance of forms of motion. Patch-light displays were recorded for 9 simple events selected to represent different kinds of dynamics including rigid body dynamics, biodynamics, hydrodynamics, and aerodynamics. Observers of the displays described the events in both a free response task and in tasks in which observers circled properties in a list. Results of cluster analyses performed on frequencies for descriptors reflected the underlying dynamics rather than crude kinematic similarities among the displays. Observers recognized specific types of nonrigid events and discriminated animate versus inanimate versions of rigid body events where only the form of the phase trajectories differed. A forced choice task confirmed the ability to discriminate animate motions based only on the form of phase space trajectories. The event kinematics were measured and investigated as information. The event dynamics were modeled to discover the properties which revealed animate activity.
Orientation was manipulated in 3 viewing conditions: 1) upright displays and observers; 2) inverted displays and upright observers; and 3) upright displays and inverted observers. Perceived event identities varied with the absolute orientation of the displays, but were unaffected by the relative orientation of display and observer. The result implies that visual event perception is, in fact, multimodal.