Factors influencing the perception of depth ambiguous apparent motion.

Abstract

what does it mean to say that an object moves? A simple answer would be to say that an object moves when it changes its spatial location during some interval of time. However, the concept of motion is considerably more complex than this simplistic definition would imply. The subtlety of the concept of motion was evident to Zeno of Elea who proposed a set of paradoxes concerning motion some 2500 years ago. Zeno's paradoxes were not resolved until the advent of modern mathematics, particularly differential calculus (Russell, 1938, pp. 347—354). An intuitive grasp of the nature of space and time is insufficient to accurately describe the motion of objects in the real world but in the phenomenal world a simple definition‘ will suffice. Despite some shortcomings, the definition of motion adopted for this discussion is that "an object appears to move when it changes its apparent spatial location during a given interval of time".