Local and Global Motion Signals and their Interaction in Space and Time

Abstract

The general issue of how we integrate local (isolated) signals into what is often termed a global percept is fundamental within vision research. The contribution by Braddick and Qian (this volume) deals specifically with the integration of local motion signals into a global motion percept but the combination of dispersed signals is a general problem with which the visual system must deal continuously. To address both the issues of general signal integration and the specific case of motion-signal integration, this commentary takes three parts. Firstly, an experimental stimulus is usually designed to simulate some component of a natural scene, so the definition of “global motion” will be discussed in the context of these artificial stimuli and also in relation to a natural image. Secondly, the parameters of the elementary local inputs to the global percept will be outlined in order to link the current commentary to the fundamental motion-detecting operations discussed in the first chapter of this book. Thirdly, I will discuss a recent discovery regarding interconnections in V1, their influence upon spatial-orientation coding and their potential relationship to the resultant percept of transparency or coherence between orthogonal motion signals in the same restricted area of space and time. I will outline a hypothesis that relates to the interaction of different fundamental image features, such as form and motion, in the process of image segmentation.