The organization of behavior: A neuropsychological theory

The computational brain: Patricia S. Churchland and Terrence J. Sejnowski (MIT Press, Cambridge, MA, 1992); xi, 544 pages, $39.95

Three-dimensional (3D) displays have become important for many applications including vision research, operation of remote devices, medical imaging, surgical training, scientific visualization, virtual prototyping, and more. In many of these applications, it is important for the graphic image to create a faithful impression of the 3D structure of the portrayed object or scene. Unfortunately, 3D displays often yield distortions in perceived 3D structure compared with the percepts of the real scenes the displays depict. A likely cause of such distortions is the fact that computer displays present images on one surface. Thus, focus cues-accommodation and blur in the retinal image-specify the depth of the display rather than the depths in the depicted scene. Additionally, the uncoupling of vergence and accommodation required by 3D displays frequently reduces one's ability to fuse the binocular stimulus and causes discomfort and fatigue for the viewer. We have developed a novel 3D display that presents focus cues that are correct or nearly correct for the depicted scene. We used this display to evaluate the influence of focus cues on perceptual distortions, fusion failures, and fatigue. We show that when focus cues are correct or nearly correct, (1) the time required to identify a stereoscopic stimulus is reduced, (2) stereoacuity in a time-limited task is increased, (3) distortions in perceived depth are reduced, and (4) viewer fatigue and discomfort are reduced. We discuss the implications of this work for vision research and the design and use of displays.

Vergence-accommodation conflicts hinder visual performance and cause visual fatigue.

Lasing in disordered media presents both theoretical challenges and practical opportunities.

/pdf/the-physics-and-applications-of-random-lasers-12d4cwd4vp.pdf

The physics and applications of random lasers

Binocular vision and ocular motility , Binocular vision and ocular motility , کتابخانه دیجیتال جندی شاپور اهواز

Binocular Vision and Ocular Motility

Spatio-temporal properties of Panum's fusional area.

Failure of rivalry at low contrast: Evidence of a suprathreshold binocular summation process

We have used stimuli with difference-of-Gaussian (DOG) luminance profiles to measure depth-increment thresholds within postulated spatial channels as functions of depth from the fixation plane. Stereoacuity was best with high-frequency DOG’s presented at the fixation plane. Performance was relatively constant for spatial frequency above 2.4 cycles/deg, but it deteriorated as spatial frequency was decreased. Regardless of spatial frequency, stereo sensitivity declined rapidly as stimuli were presented away from the horopter. The falloff occurred more rapidly over the 0–20-arc-min range than over the 20–80-arc-min range. Depth was perceived over a broader range of disparity pedestals with low-spatial-frequency stimuli; however, the lowest thresholds were always obtained with the highest-frequency stimuli. Both the falloff of sensitivity with disparity pedestal and the disparity range of quantitative stereo depth lead to the conclusion that different size-tuned channels process disparity differently.

Clifton M. Schor

Papers

Spatio-temporal properties of Panum's fusional area.

Failure of rivalry at low contrast: Evidence of a suprathreshold binocular summation process

Depth-increment detection function for individual spatial channels.

Spatial tuning of static and dynamic local stereopsis

Negative feedback control model of proximal convergence and accommodation.