Towards a theory of apparent visual motion

Abstract

The existence of two separate mechanisms for the processing of apparent motion, the short- and long-range processes, as proposed by O. Braddick (1974), has been analyzed through many different psychophysical experiments. In particular, the fact that for the short-range process there exists an upper bound for the spatial displacement and temporal interstimulus interval between successive stimulus presentations was confirmed by various experiments. Here, the author attempts to obtain a more formal understanding of these issues by analyzing the phenomenon of apparent motion from the point of view of a reconstruction problem. This makes it possible to use the sampling theorem to analyze the problem of temporal (spatial) reconstruction of uniformly translating patterns. In the case where the velocity field can only be extracted with uncertainty, it can be shown that there exists a maximum temporal (spatial) sampling interval, such that aliasing does not occur. It is argued that, in the case of short-range process, due to its temporal (spatial) reconstruction ability, a similar effect could intervene in the limitation of its activity to a small spatiotemporal scale.<>