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

Vergence eye movements : basic and clinical aspects

Binocular sensory fusion is limited by spatial resolution

Disparity range for local stereopsis as a function of luminance spatial frequency

The relationship between fusional vergence eye movements and fixation disparity.

Horizontal and vertical small-field optokinetic nystagmus (OKN) were examined in persons with strabismic or anisometropic amblyopia. Reduced velocity for the slow phase of OKN driven by temporalward and upward target motion presented monocularly was observed in both the amblyopic and nonamblyopic eyes of some subjects. Several experiments were conducted in search of a sensory disturbance of perceived motion sensitivity which could account for the abnormal OKN. Comparisons between the frequency response for OKN and the contrast sensitivity function for perceived motion revealed that amblyopes with asymmetric OKN had equal sensitivity to nasal and temporal target motion. Contrast thresholds for driving the temporal slow phase of OKN were elevated by over 1 log unit above contrast thresholds for perceived temporal target motion, whereas contrast thresholds for stimulating nasal movement and driving the nasalward slow phase of OKN were equal. Contrast sensitivity to nasal and temporal target motion was symmetrical at thefovea and parafovea of the amblyopic eye. These studies did not reveal a sensory anomaly as the basis for abnormal OKN in amblyopia. Directional asymmetries in OKN were also observed in both eyes of persons with congenital strabismus without amblyopia and in the nondeprived eye in monocular congenital cataract. These observations suggest a relationship between directional asymmetries of OKN and the incomplete development of binocular vision.

Clifton M. Schor

Papers

Vergence eye movements : basic and clinical aspects

Binocular sensory fusion is limited by spatial resolution

Disparity range for local stereopsis as a function of luminance spatial frequency

The relationship between fusional vergence eye movements and fixation disparity.

Disturbances of small-field horizontal and vertical optokinetic nystagmus in amblyopia.