... This article presents one alternative to the computer metaphor suggesting that brains are organized into independent modules. Evidence is reviewed that brains are organized into parallel processing streams with complementary properties. Hierarchical interactions within each stream and parallel interactions between streams create coherent behavioral representations that overcome the complementary deficiencies of each stream and support unitary conscious experiences. This perspective suggests how brain design reflects the organization of the physical world with which brains interact. Examples from perception, learning, cognition, and action are described, and theoretical concepts and mechanisms by which complementarity is accomplished are presented.

Abstract not found

The geometry of binocular projection is analyzed in relation to the primate visual system. An oculomotor parameterization that includes the classical vergence and version angles is defined. It is shown that the epipolar geometry of the system is constrained by binocular coordination of the eyes. A local model of the scene is adopted in which depth is measured relative to a plane containing the fixation point. These constructions lead to an explicit parameterization of the binocular disparity field involving the gaze angles as well as the scene structure. The representation of visual direction and depth is discussed with reference to the relevant psychophysical and neurophysiological literature. © 2008 Optical Society of America OCIS codes: 330.1400, 330.2210. 1.

... This article presents one alternative to the computer metaphor suggesting that brains are organized into independent modules. Evidence is reviewed that brains are organized into parallel processing streams with complementary properties. Hierarchical interactions within each stream and parallel interactions between streams create coherent behavioral representations that overcome the complementary deficiencies of each stream and support unitary conscious experiences. This perspective suggests how brain design reflects the organization of the physical world with which brains interact. Examples from perception, learning, cognition, and action are described, and theoretical concepts and mechanisms by which complementarity is accomplished are presented.

Theories of cue combination suggest the possibility of constructing visual stimuli that evoke different patterns of neural activity in sensory areas of the brain, but that cannot be distinguished by any behavioral measure of perception. Such stimuli, if they exist, would be interesting for two reasons. First, one could know that none of the differences between the stimuli survive past the computations used to build the percepts. Second, it can be difficult to distinguish stimulus-driven components of measured neural activity from top-down components (such as those due to the interestingness of the stimuli). Changing the stimulus without changing the percept could be exploited to measure the stimulusdriven activity. Here we describe stimuli in which vertical and horizontal disparities trade during the construction of percepts of slanted surfaces, yielding stimulus equivalence classes. Equivalence class membership changed after a change of vergence eye posture alone, without changes to the retinal images. A formal correspondence can be drawn between these "perceptual metamers" and more familiar "sensory metamers" such as color metamers.