Large scale stereopsis and optic flow: Depth enhanced by speed and opponent-motion

To understand better the range of conditions supporting stereoscopic vision, we explored the effects of speed, as well as specific optic flow patterns, on judgments of the depth, near or far of fixation, of large targets briefly presented in the upper periphery, They had large disparities (1-6 deg) and moved at high speeds (20-100 deg/sec). Motion was either vertical or horizontal, as well as either unidirectional or layered in bands of alternating directions (opponent-motion), High stimulus speeds can extend d(max) The effects are explained by models having linear filters that signal both faster speeds and larger disparities. Stereo depth localization can also be enhanced by opponent-motion even when kinetic depth itself is not apparent. Improvements are greatest with wide-field, horizontal opponent-motion. The results imply functions such as vection, posture-control, and vergence may benefit from disparity information enhanced by optic flow patterns that are commonly available to a moving, binocular observer. (C) 1998 Elsevier Science Ltd. All rights reserved.