Perceptual atoms: proximal motion vector-structures and the perception of object motion in depth

Abstract

This paper proposes a framework for analyzing the perception of motion in depth produced by simple proximal motion patterns of two to four points. The goal is to provide a single framework for understanding the perception of rigid object motions produced by the moving points as well as nonrigid outcomes such as shrinking, stretching, bending, and folding. The framework includes input structure, perceptual system constraints, and a depth scaling mechanism. The input consists of relational stimulation described by two proximal dimensions, orientation and separation, that can change or remain constant over the course of a motion pattern. Combinations of change or no-change in these dimensions yield four basic patterns describing the motion of two proximal points: parallel, circular, perspective, and parallax patterns. Pairs of points are processed automatically according to operating characteristics of the perceptual system described as unity and rigidity constraints. The processing includes a depth scaling mechanism to maintain perceived rigidity and induce the perception of motion in depth. Although this framework is sufficient to explain perceptions produced by Perceptual atoms: proximal motion vector-structures and the perception of object motion in depth ABSTRACT Keywords: Perception; Motion; Rigidity; Vectors; Depth A framework is proposed for analyzing the perception of motion in depth produced by simple proximal motion patterns of two to four points. The framework includes input structure, perceptual system constraints, and a depth scaling mechanism. The input is relational stimulation described by two proximal dimensions, orientation and separation, that can change or remain constant over the course of a motion pattern. Combinations of change or no-change in these dimensions yield four basic patterns of proximal stimulation: parallel, circular, perspective, and parallax. These primary patterns initiate automatic processing mechanisms -a unity constraint that treats pairs of points as connected and a rigidity constraint that treats the connection as rigid. When the constraints are activated by perspective or parallax patterns, the rigid connection between the points also appears to move in depth. A scaling mechanism governs the degree to which the objects move in depth in order to maintain the perceived rigidity. Although this framework is sufficient to explain perceptions produced by three-and four-point motion patterns in most cases, some patterns require additional configurational factors to supplement the framework. Nevertheless, perceptual qualities such as shrinking, stretching, bending, and folding emerge from the application of the same processing constraints and depth scaling factors as those that produce the perception of rigid objects moving in depth.