The processing of linear perspective and binocular information for action and perception.
Yonas and his colleagues looked for evidence for Goodale’s theory that there are two pathways in the visual system; 1) a ventral pathway that is dependent on recognition of patterns, produces representations of subjective experiences ; and 2) a dorsal pathway that controls rapid action. The processing of linear perspective and binocular information for action and for the perceptual judgment of depth was investigated by presenting viewers with a static Ames trapezoidal window (see figure on right). The display was presented perpendicular to the line of sight but it created an illusion of a rectangular window slanted in depth, on the other hand binocular information specified a non-slanted surface.
We compared pointing towards the display-edges with perceptual judgment of their positions in depth as the display orientation was varied under monocular and binocular view. On monocular trials, pointing and depth judgment were based on the perspective information and failed to respond accurately to changes in display orientation because pictorial information did not vary sufficiently to specify the small differences in orientation. For binocular trials, pointing was based on binocular information and precisely matched the changes in display orientation whereas depth judgment was short of such adjustment and based upon both binocular and perspective-specified slant information. The finding, that on binocular trials pointing was considerably less responsive to the illusion than perceptual judgment, supports an account of two separate processing streams in the human visual system, a ventral pathway involved in object recognition and a dorsal pathway that produces visual information for the control of actions. Previously, similar differences between perception and action were explained by an alternate explanation, that is, viewers selectively attend to different parts of a display in the two tasks. The finding that under monocular view participants responded to perspective information in both the action and the perception task rules out the attention-based argument.
The purpose of the snowplow experiment is to investigate the effects of various lighting schemes on the ability of drivers to detect the presence of snowplow in front of them using a computer generated program. The results of the experiment will help us understand how to design the lighting scheme on snowplows to reduce rear-end crashes.
Research was conducted by lab staff and the results were presented to the Minnesota Department of Transportation.