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VISION SCIENCE .

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Some Aspects of the Basis of Stereoscopic Vision Kenneth N. Ogle 1953 This report discusses whether simultaneity is a factor associated with disparity between the images in the two eyes and is necessary for the emergence of the stereoscopic experience. It is well known that stereop- sis can be obtained from disparate afterimages that are induced in each eye separately. Experiments show, however, that stereoscopic depth from afterimages is experienced only as long as the disparate retinal elements involved are in an excited state at the same time. Simultaneity with respect to retinal location concerns the question whether the disparate stimuli, at least in part, must fall on specific horizon- tally associated disparate retinal elements. In 1873, van der Meulen and van Dooremaal reported their observations that bear on this question. They used the Hering "falling sphere" test. In this test, through a horizontal slit-aperture, the subject views a vertical thread (plumb line) as a fixation object and judges whether a small sphere dropped by an assistant appears to fall in front of or behind the fixed plumb line. A prism was placed base down before one eye so that the image of the slit to the eye would be seen entirely above the actual slit seen by the other eye. The images of the plumb line would be uninfluenced and would appear just the same as before. A small sphere now dropped near the plumb tide would not be seen simultaneously by the two eyes. The upper half of the path of the fall would be seen by one eye, the lower half of the path would be seen by the other eye. It was reported that the path of the falling sphere nevertheless could always be correctly judged nearer or farther than the plumb line. These authors concluded that stereoscopic depth is not to be conceived as a direct physiological phenomenon but as a psychical one, that is, the depth is produced by a psychophysical process. In this experiment, the stereoscopic vision arises solely through the means of imagined prolongations of the half- images, which then in the usual stereoscopic manner would be referred to horizontally disparate retinal points. 6 pp. no figures no tables 6 references Availabiliy: Committee on Vision, 2101 Constitution Ave., N.W., Wash- ington, D.C. 20418. 81

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An Annotated Bibliography of Flicker-Fusion Phenomena: Covering the Period 1740-1952 Carney Landis 1953 In 1948, evaluation of the experimental findings of the Columbia- Greystone Brain Research Project suggested that the critical flicker-fusion threshold was probably lowered as a result of surgical ablation of portions of the human frontal lobes. A search for information in textbooks, hand- books, and monographs dealing with the physiological psychology of vision nowhere provided either an explanation of the observation nor indeed a comprehensive treatment of the flicker-fusion phenomena. It became ap- parent that many investigations had been made of flicker-fusion phenomena but there was no comprehensive theory or review of the topic. Flicker-fusion phenomena have been investigated by one or more persons working in various disciplines, e.g., physics, chemistry, mathemat- ics, physiology, zoology, botany, neurology, ophthalmology, optometry, as- tronomy, anatomy, pathology, internal medicine, endocrinology, nutrition, pharmacology, biology, biophysics, biochemistry, electrical engineering, il- luminating engineering, and psychology. Flicker-fusion phenomena have been discussed under titles such as: persistence of vision, photopic versus scotopic vision, visual beats, visual ripple, intermittent vision, and duration of retinal impressions. They have been studied in many states of physical and mental pathology. The effect of a wide variety of drugs, chemicals, hormones, and the like on flicker-fusion phenomena has been reported. Yet, despite the fact that it has entered into such a wide variety of inves- tigations, there is no comprehensive theory of flicker. The general theory of Plateau (1834) is as complete as that of any of his successors. Marbe, V. Kries, Sherrington, McDougall, Ives, Hecht, Crazier, and Ross have theorized, but in each instance in a limited fashion that encompassed only part of the available factual evidence. Even such a simple point as whether the flicker-fusion threshold is dependent on retinal functional limitations or on limitations imposed by the central nervous system has never been clearly answered. 130 pp. no figures no tables 1,300 annotated entries (2,000 references) Availability: National Technical Information Sentence ~S), 5285 Port Royal Road, Springfield, VA 22161. 82

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The Measurement of Visual Function Milton ~ Whitcomb and William Benson, Editors 1965 The purpose of this report is to provide a basis for reevaluating the testing procedures for each of the different visual parameters useful in visual classifications. A working group of the Committee on Vision reevaluated some of the aspects of the visual requirements for flying and made some general conclusions and recommendations regarding visual requirements, visual standards for performance tasks in general, and the role of the visual scientists in assessing visual capabilities and in assisting the agencies and services with their needs for visual classification systems. The laboratory methods of assessing each visual function are presented in order to update the awareness of all possible testing techniques available in assessing the considered visual parameter. The clinical presentations are directed toward assessing those techniques best suited for practical utilization in measuring the considered visual parameter by (a) professional personnel, (b) nonprofessional (technical) personnel, and (c) machine or semiautomated methods. Special reference is made to updating techniques such as the utilization of electrodes, machines (orthorator types), and other semiautomated techniques capable of quantifying or scaling the test scores. Where appropriate, comments are made relative to training of the visual function and predictability of change with age. The material presented provides a basis for making judgments relative to the preferred testing techniques best suited for the needs of the different agencies and services requiring visual classification and testing. These conclusions are derived from, or compared with, the array of laboratory techniques available. The concern is with the testing techniques most suitable for scoring and classification. The papers presented in this volume are concerned with ideal and practical techniques for the measurement of each of the selected visual functions and cover the following topics: visual acuity; refractive error; color vision; distance vision; phoria and ocular rotation; accommodative amplitude; night vision; visual fields; intraocular tension; stress tolerance; and clinical and laboratory measurement of visual functions (other than those mentioned). 260 pp. 89 figures 4 tables 361 references Availabiluy: National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161. 83

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Eye Movements and Psychological Processes Richard ~ Montr and John W. Senders, Editors 1976 This volume brings together scientists from such disciplines as neurol- ogy, physiology, engineering, medicine, and psychology to examine many aspects of eye movement. It begins with an examination of the physiology of eye movement control and then examines the role of eye movements in vision, methods of recording eye movements, the relation of eye movements to the perception of motion, position, and kinds of visual stimuli. Specific fields such as target detection, search and scanning, reading behavior, and highest cognitive processes are examined. 550 pp. 22 figures 21 tables 497 references Availabilz~y: Lawrence Erlbaum Associates, Hillsdale, N.J. 84

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Electrophysiological Techniques in Vision 1977 This volume, the proceedings of a 1975 symposium, includes papers presented at the symposium on five major topics relevent to electrophysi- ological techniques for studying human visual functions. First, a historical overview provides a brief description and appraisal of the techniques that have been developed for stimulating and recording the visual responses of the human eye and brain. Second, psychophysical applications of hu- man electroretinography are given: rapid developments in human elec- troretinography during recent decades have greatly increased its value for investigating psychophysical problems. This review of the current status of electroretinography considers the response waveform, recording tech- niques, and data analysis. Several examples of electroretinal data that have psychophysical significance are presented. Third, transient visually evoked potentials are discussed. Fourth, steady-state evoked potentials are treated. Finally, spatiotemporal mapping of scalp potentials are covered. 43 pp. 84 figures no tables 154 references Availability: The Journal of the Opacal Society of America Vol. 67, No. 11, pp. 1451-1494, 1977. 85

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Effects of Microwave Radiation on the Lens of the Eye 1981 A working group of the Committee on Vision was formed in response to concern expressed by representatives of several federal agencies about workers who may be exposed to microwave radiation. The committee was requested to review the scientific literature concerning ocular effects of microwave radiation and to comment on the adequacy of existing studies, particularly in regard to the potential for ocular damage from microwave exposure below the current standard. The Department of the Air Force also requested comment on the desirability of routine screening for ocular changes in all its personnel working around microwave devices. Potential hazards of human exposure to microwave radiation are of considerable concern because large numbers of people in the military ser- vices and in industry work in the vicinity of microwave generators and also because people may be exposed to radiation from devices such as microwave ovens and diathermy devices used in physical therapy. Cataractogenesis is the most clearly documented irreversible effect of overexposure to mi- crowave radiation, but the mechanisms underlying this effect are poorly understood. The current standard for maximum permissible occupational exposure to microwave radiation, recommended by the American National Stan- dards Institutes (ANSI), is lOmW/cm2. This report surveys existing studies of cataract induction by microwave radiation exposure and discusses the im- plications of this literature for human exposure at levels below l()mW/cm2. The report also suggests the kinds of study still needed. The report does not comment on the appropriateness of the existing standard. Standards for whole-body exposure are based on considerations of all possible biological effects and also on policy issues such as degree of acceptable nsk, margin of safety, and cost-benefit considerations. 13 pp. no figures no tables 55 references Availability: Committee on Vision, 2101 Constitution Ave., N.W., Ubsh- ington, D.C. 20418. 86

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Emergent Techniques for Assessment of Visual Performance 1985 Recent vision research has led to the emergence of new techniques that offer exciting potential for a more complete assessment of vision in clinical, industrial, and military settings. Four areas of vision testing are examined in this report: (1) contrast sensitivity function; (2) dark focus of accommodation; (3) dynamic visual acuity and dynamic depth tracking; and (4) ambient and focal vision. Each of these topics is discussed in a separate section of the report; each section focuses on issues related to screening industrial and military visual functions. The report concludes with summary recommendations for research. The report text is followed by four appendices that give additional information and detail on spatial contrast sensitivity, detection sensitivity and response bias, Founer analysis, and the use of tests for screening and selection. 66 pp. 23 figures no tables 181 references Availability: Pubh~tion on Demand, National Academy Press, 2101 Con- stitution Ave., N.W., Washington, D.C. 20418. 87

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Vision Research Reports E. Porter Horne and Milton ~ Whitcomb, Editors 1960 The purpose of this volume is to bring together the summaries of the scientific papers that were presented at the 36th, 37th, and 39th annual meetings of the Committee on Vision. The papers presented at the 38th annual meeting, which was devoted primarily to the symposium on visual search, were included in the proceedings of that symposium (see Visual Search Techniques). At the 37th annual meeting, in addition to papers summarized herein, a symposium on illumination and visibility of radar and sonar displays was held. That portion of the meeting is also reported in Illumination and Visibility of Radar and Sonar Displays (see below). This report includes such topics as: recognition of forms against a complex background; accommodation levels in emptier visual fields; the status of research on the effect of pre-exposure on dark adaptation; the intensity factors in vision; and, general color-vision theory. 182 pp. 97 figures 4 tables 260 references Availability: National Technical Information Service ~IS), 5285 Port Royal Road, Springfield, VA 22161. 88

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Recent Developments in Vision Research Milton ~ Whitcomb, Editor 1966 The papers presented in this report concern recent developments in vision research. Topics covered include: (1) recent advances in the study of physiological reflex mechanisms in vision, (2) recent advances in instrumentation and procedures in vision research, and (3) the effects of drugs on vision. The papers presented are the following: "Focusing Responses of the Human Eye," G. Westheimer; "Pupilla~y Movements Associated with Light and Near Vision: An Experimental Review of the Literature," I.E. Loewen- feld; "The Fusion Reflex," KN. Ogle; "Vestibular Mechanisms and Vision," E.F. Miller II and ~ Graybiel; "Visual Psychophysics with Animals," D.S. Though; "Measurements of Light Reflected from the Retina," J. Krauskopf; "Stabilized Image Techniques," T.N. Cornsweet; "Principles of Neurological Feedback Control Systems for Eye Muscles," L. Stark; "Ocular Pharmaco- dynamics," NM. Potts; "The Sensory Effects of Drugs: Electrophysiologi- cal Investigations of the Mechanism of the Action of Drugs on the Eye," G.B. Arden; "Studies in the Pharmacology of Extraocular Muscles," G.M. Breinin and J.H. Perryman; "Drug and Eye Movement Responses in Man," G. Westheimer; "The Effects of Drugs on Vision," IFS. Otis; and "Some Potential of Research on Drugs and Vision," R. Trumbull. 227 pp. 88 figures 10 tables 509 references Availabd~: AD 627186, National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161. 89

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Vision Research in Military and Government Laboratories John Lott Brown 1967 Fairly extensive research on a variety of aspects of vision is conducted within service laboratories in the Air Force, the Army, and the Navy. There is also some research on visual processes conducted in laboratories by the Coast Guard and by the National Aeronautics and Space Administration. The Committee on Vision requested information concerning their in-house research; this report summarizes the results of that survey and describes the type and amount of vision research being done in the military and government laboratories. References cited in this report indude those received as a result of that survey. They are neither complete nor a representative sample of all the work in military laboratories. 22 pp. no figures no tables 63 references Availability: Committee on Vision, 2101 Constitution Ave., N.W., Wash- ington, D.C. 20418. 90

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Frontiers of Visual Science: Proceedings of the 1985 Symposium 1987 Vision research is a science in transition. The improved understanding of genetics at the molecular level and rapid advances in computer architec- ture suggest that vision scientists are no longer limited in the methods and models available to them to tackle the most challenging research questions. The rate of advance in our understanding of the visual system is not yet equal, however, to that of technical advance. The transition will be com- plete when vision research has fully integrated the most promising of these new approaches and renewed the expansion of its knowledge base. On December 11, 1985, the Committee on Vision brought together 14 leading investigators in vision research whose work embodies the integration of some of these newer models and methods. Participants illustrated how new approaches to fundamental visual processes have significantly improved our understanding of.spatial vision, stereoscopic depth perception, color consistency, and color vision. The advantages of these new models are discussed with methods for attacking problems of vision along many fronts. The pitfalls and areas in which some of these new approaches fail to explain visual function are also considered. The symposium report is divided into three parts, reflecting the three- part structure of the program: (1) developments in the ideal observer concept; (2) computational theories for vision research; and (3) cone pigments and color vision polymorphism. 198 pp. 40 figures 1 table 192 references Availability: National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161. 91

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Advances in the Modularity of Vision: Selections From a Symposium on Frontiers of Visual Science 1990 Converging lines of evidence indicate that the brain contains multiple neural representations (i.e., maps) of visual space, with different maps devoted to the analysis of different aspects of the visual scene. From a computational standpoint, such a processing arrangement makes good sense given the properties of the brain. Moreover, neurophysiologists have actually documented that the primate cortex is divisible into distinct visual maps, with as much as 60 percent of the cortex concerned with vision. Others are now using noninvasive techniques (e.g., positron emission tomography) to study local regions of brain activity in alert humans. And neurologists have known for some time that focal lesions can produce highly specific losses of visual function. This is the report of a 1987 symposium that brought together in- dividuals from these fieldscomputational theory, neurophysiology, and neurologyto discuss: (1) evidence for the modularity of vision; (2) topo- graphic versus nontopographic mapping; (3) the plasticity of modules (i.e., to what extend can one module take over the function of another?; (4) means by which perceptual unification of the visual world occurs; and (5) the relation of the modularity concept to other functional concepts, such as focaVambient distinction. Approve: 70 pp. 31 figures no tables 52 references Availability: Committee on Vision, 2101 Constitution Ave., N.W., Wash- ington, D.C. 20418. 92

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Advances in Photoreception: Proceedings of a Symposium on Frontiers of Visual Science 1990 Vision begins with the transduction of light into neural signals by photoreceptors. Significant recent advances in our understanding of this process of photoreception include the precise measurement of the wave- lengths absorbed by visual pigments in the human eye and the role of the molecule cyclic GMP in the transduction of light to photocurrent. Another area of recent progress is the analysis of the spatial mosaic of photoreceptors. The sampling of the visual image by the photoreceptor lat- tice influences visual acuity and sensitivity. Disorders of the array of cones as a consequence of retinal disease may well be the cause of perceptual deficits. Future research on vision will depend upon these new fundamental findings about photoreception. This volume presents the work of scientific leaders on this frontier of vision research. The 1988 symposium speakers included visual physiolo- gists and psychophysicists. The volume covers: (1) wavelength specificity of visual pigments; (2) receptor transduction in health and disease; (3) adaptation of photoreceptors to light; (4) variations of the photoreceptor lattice across the retina; and (5) photoreceptor sampling of visual images and aliasing. Compansons between human and animal retinas are offered, and differences between photoreceptor function in normal and diseased eyes are emphasized. 156 pp. 39 figures 2 tables 214 references Availability: National Academy Press, 2101 Constitution Ave., N.W., Wash- ington, D.C. 20418. 93 .

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