Conceptualizations of Short-Range and Long-Range Processes in Apparent Movement

Abstract

The two-process distinction in apparent movement posits the existence of competitive `short-range' and `long-range' processes. It was proposed to account for the fact that the visual system seems to generate different qualitative percepts under different spatiotemporal conditions of stimulation. It has been shown to be in accord with empirical data from random-dot cinematogram experiments and bistable-percept experiments, as well as with subjective experience. Although it has been developed by some into a model of motion perception, the two-process distinction is perhaps best conceptualized as a metatheoretical perspective rather than a theory. That is, the two-process distinction has guided the development of a number of theories, all of which share the notion of a basic processing dichotomy. The present paper elaborates these ideas and addresses criticisms of the two-process distinction, arguing that they inappropriately test the processes against fixed `criteria'. It is claimed here that, like all complex perceptual processes, those associated with the two-process distinction cannot be easily isolated by manipulations of individual stimulus parameters in the search for criterion behavior. The nature of perceptual theories is discussed in this context, and the notion of modes of perceiving is used as a conceptualization for the two-process distinction. Consistency between the two-process distinction and other theoretical conceptualizations is shown. Conclusions are drawn and suggestions are made for the future of the two-process distinction.