The importance of event dynamics in determining the perceptual significance of motions in events was investigated. 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 duster analyses performed on frequencies for descriptors reflected the underlying dynamics rather than crude kinematic similarities among the displays. Observers discriminated animate versus inanimate versions of rigid body events where only the form of the phase trajectories differed.
Three viewing conditions were used as a between-subjects manipulation including upright displays and observers, inverted displays and upright observers, and upright displays and inverted observers. Perceived event identities varied with the absolute orientation of the displays with respect to gravity, but were unaffected by the relative orientation of display and observer.
Finally, the event kinematics were measured and investigated as the source of information for event identities. A force choice task confirmed the ability to discriminate animate motions based only on the form of phase space trajectories. The dynamics of these events was modeled to discover the properties which revealed animate activity.