Download or read book Parallel Processing in the Visual System written by Jonathan Stone and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the mid-sixties, John Robson and Christina Enroth-Cugell, without realizing what they were doing, set off a virtual revolution in the study of the visual system. They were trying to apply the methods of linear systems analysis (which were already being used to describe the optics of the eye and the psychophysical performance of the human visual system) to the properties of retinal ganglion cells in the cat. Their idea was to stimulate the retina with patterns of stripes and to look at the way that the signals from the center and the antagonistic surround of the respective field of each ganglion cell (first described by Stephen Kuffier) interact to generate the cell's responses. Many of the ganglion cells behaved themselves very nicely and John and Christina got into the habit (they now say) of calling them I (interesting) cells. However. to their annoyance, the majority of neurons they recorded had nasty, nonlinear properties that couldn't be predicted on the basis of simple summ4tion of light within the center and the surround. These uncoop erative ganglion cells, which Enroth-Cugell and Robson at first called D (dull) cells, produced transient bursts of impulses every time the distribution of light falling on the receptive field was changed, even if the total light flux was unaltered.

Download or read book Applications of Parallel Processing in Vision written by J.R. Brannan and published by Elsevier. This book was released on 1992-01-23 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: Considerable evidence exists that visual sensory information is analyzed simultaneously along two or more independent pathways. In the past two decades, researchers have extensively used the concept of parallel visual channels as a framework to direct their explorations of human vision. More recently, basic and clinical scientists have found such a dichotomy applicable to the way we organize our knowledge of visual development, higher order perception, and visual disorders, to name just a few. This volume attempts to provide a forum for gathering these different perspectives.

Download or read book The Primate Visual System written by Jon H. Kaas and published by CRC Press. This book was released on 2003-07-28 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last 20 years of research have been marked by exceptional progress in understanding the organization and functions of the primate visual system. This understanding has been based on the wide application of traditional and newly emerging methods for identifying the functionally significant subdivisions of the system, their interconnections, the

Download or read book New Methods of Sensory Visual Testing written by Michael Wall and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurement of visual acuity has been the cornerstone of visual testing since Snellen began quantitating visual acuity using letter optotypes in the 1860s. Bjerrum in the 1880s brought sophistication and quantitation to the assessment of the visual field with tangent screen examination using differently sized and colored targets. Further advances in visual testing did not occur until the Goldmann perimeter and the Farnsworth Munsell 100 Hue test were introduced in the 1940s, permitting further refinement in the detection and quantitation of acquired visual loss. An explosion of interest in sensory visual function testing followed the demonstration by Quigley and his colleagues in 1982 that despite the loss of more than 40% of the axons in the optic nerve, Snellen acuity and kinetic perimetry remained normal. Much of this interest has focused on a search for more sensitive and disease-specific sensory visual tests. Previously, novel tests used to probe visual function remained in the province of the visual physiologist and psychophysicist. These tests are now being introduced by the ophthalmologist into clinical practice. Concomitantly, the mass production of microcomputers and other technical advances have made tests such as automated perimetry and visual evoked response testing affordable for most offices. The clinician is presently being inundated with a plethora of visual function tests that may require a knowledge of visual psychophysics and statistics to understand and interpret. The purpose of this book is to acquaint the clinician with these new tests so that they may be used to maximum benefit.

Download or read book Vision and the Visual System written by Peter H. Schiller and published by Oxford University Press, USA. This book was released on 2015 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'Vision and the Visual System' offers students, teachers and researchers a rigorous, yet accessible account of how the brain analyses the visual scene. Schiller and Tehovnik describe key aspects of visual perception such as colour, motion, pattern and depth while explaining the relationship between eye movements and neural structures in the brain.

Download or read book Contributions of Early Parallel Pathways to Extrastriate Visual Cortex in Macaque Monkey written by Jonathan J. Nassi and published by . This book was released on 2007 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: All together, these studies provide strong evidence for the existence of multiple circuits between LGN and MT. Each pathway receives a different combination of M and P inputs and is uniquely suited to convey visual information with varying degrees of spatial and temporal resolution, contrast sensitivity, and color selectivity. Distinct cell types underlie many of these circuits, overcoming the lack of spatial compartmentalization of V1 outputs. Functional studies that can target these specialized cell types and circuits will be necessary to elucidate the contributions of each pathway to response properties in MT and, ultimately, to visual perception and behavior.

Download or read book Higher Order Processing in the Visual System written by Gregory R. Bock and published by John Wiley & Sons. This book was released on 2008-04-30 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Foremost neurophysiologists and psychophysicists provide pertinent information on the nature of representation at the earliest stages as this will constrain the disposition of all subsequent processing. This processing is discussed in several different types of visual perception.

Download or read book Brain and Visual Perception written by David H. Hubel M.D. and published by Oxford University Press. This book was released on 2004-10-14 with total page 739 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the story of a hugely successful and enjoyable 25-year collaboration between two scientists who set out to learn how the brain deals with the signals it receives from the two eyes. Their work opened up a new area of brain research that led to their receiving the Nobel Prize in 1981. The book contains their major papers from 1959 to 1981, each preceded and followed by comments telling how and why the authors went about the study, how the work was received, and what has happened since. It begins with short autobiographies of both men, and describes the state of the field when they started. It is intended not only for neurobiologists, but for anyone interested in how the brain works-biologists, psychologists, philosophers, physicists, historians of science, and students at all levels from high school to graduate level.

Download or read book Webvision written by Helga Kolb and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Parallel and Competitive Processes in Low Level Vision and Their Impact on Awareness written by Rachel Denison and published by . This book was released on 2013 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perception consists of the brain's single best interpretation of the sensory world at a given moment in time. Multiple channels of visual input - be they from the two eyes or from the many parallel visual pathways that originate as early as the retina - must be reconciled to arrive at a unified percept. The fact that this must occur in roughly real time as the visual scene changes poses special challenges and constraints. I investigated two classes of visual processes relevant for the perception of time-varying visual stimuli: prediction, with a probable neural substrate in early visual cortical areas, and parallel processing in the magnocellular (M) and parvocellular (P) pathways. In Chapters 2 and 3, I asked how prediction and parallel pathways, respectively, contribute to perceptual selection using dynamic binocular rivalry stimuli. In binocular rivalry, incompatible images presented to the two eyes result in just one of the images being selected for awareness at any given time. This bistability makes rivalry a useful tool for the study of perceptual selection. In Chapter 2, we found that predictive context in the form of an unambiguous rotating grating biased perceptual selection during subsequent rivalry towards the expected next grating in the rotation sequence, compared to an orthogonal grating. This provided evidence that a prediction-like process influences perceptual selection during rivalry between gratings, which other work has shown is likely resolved at early stages of visual processing. In Chapter 3, we studied spatial, temporal, luminance, and chromatic factors influencing perceptual selection during interocular switch rivalry. In this type of rivalry, flickering orthogonal gratings are periodically exchanged between the two eyes, resulting in either the perception of a fast, regular alternation between orthogonally oriented gratings (similar to the display presented to a single eye) or a slow, irregular alternation, a percept that requires integration across the two eyes over time. We found that stimuli biased toward the M pathway increased the prevalence of fast, regular alternations, while stimuli biased toward the P pathway increased the prevalence of slow, irregular alternations. This finding suggested that the M and P pathways can make distinct contributions to perception during binocular rivalry and led us to propose a new framework for understanding perceptual selection during interocular switch rivalry. Physiological measurement of activity in the M and P pathways can lead to greater understanding of how these pathways contribute to perceptual experience, but methods for measuring functional signals from the M and P pathways of humans have been lacking. Therefore, in Chapter 4, we developed a procedure for functionally mapping the M and P subdivisions of human LGN, the site where these pathways are most clearly segregated, using functional magnetic resonance imaging (fMRI). We observed a gradient of more M-like to more P-like responses across the LGN. Importantly, this gradient had a spatial layout consistent with known LGN anatomical organization. This new method for localizing the M and P subdivisions of the LGN provides a way forward for investigating the function of these pathways in human visual perception, in both healthy and clinical populations. In summary, prediction and parallel processing are two classes of mechanisms that contribute to perception of dynamic visual stimuli. Here we have shown how such mechanisms operating at low levels of the visual system can help resolve competition between percepts, thereby affecting the contents of visual awareness. In addition, we developed a method for the physiological study of the M and P LGN subdivisions in the human brain, which is a promising technique for the future investigation of the roles of the M and P pathways in human visual perception, among other applications.

Download or read book Visual Perception written by Lothar Spillmann and published by Elsevier. This book was released on 2012-12-02 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an interdisciplinary overview of the main facts and theories that guide contemporary research on visual perception. While the chapters cover virtually all areas of visual science, from philosophical foundations to computational algorithms, and from photoreceptor processes to neuronal networks, no attempt has been made to provide an exhaustive treatment of these topics. Rather, researchers from such diverse disciplines as psychology, neurophysiology, anatomy, and clinical vision sciences have worked together to review some of the most important correlations between perceptual phenomena and the underlying neurophysiological processes and mechanisms. The book is thus intended to serve as an advanced text for graduate students and as a guide for all vision researchers to understanding current progress outside their specialized fields of interest.ï Examines parallel processing of visual informationï Discusses links between physiologically-measured receptive fields and psychophysically-measured perceptive fieldsï Presents a spatial sampling by the retina and cortical modulesï Covers signal transduction and the sites of adaptationï Describes a single-cell analysis of attentionï Discusses computational models of vision

Download or read book Describing Nature Through Visual Data written by Ursyn, Anna and published by IGI Global. This book was released on 2020-07-03 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: People have described nature since the beginning of human history. They do it for various purposes, including to communicate about economic, social, governmental, meteorological, sustainability-related, strategic, military, and survival issues as well as artistic expression. As a part of the whole world of living beings, we use various types of senses, known and unknown, labeled and not identified, to both communicate and create. Describing Nature Through Visual Data is a collection of impactful research that discusses issues related to the visualization of scientific concepts, picturing processes, and products, as well as the role of computing in advancing visual literacy skills. Organized into four sections, the book contains descriptions, theories, and examples of visual and music-based solutions concerning the selected natural or technological events that are shaping present-day reality. The chapters pertain to selected scientific fields, digital art, computer graphics, and new media and confer the possible ways that visuals, visualization, simulation, and interactive knowledge presentation can help us to understand and share the content of scientific thought, research, artistic works, and practice. Featuring coverage on topics that include mathematical thinking, music theory, and visual communication, this reference is ideal for instructors, professionals, researchers, and students keen on comprehending and enhancing the role of knowledge visualization in computing, sciences, design, media communication, film, advertising, and marketing.

Download or read book Foundations of Neuroscience written by Casey Henley and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Cost of Parallel Processing in the Human Visual System written by Reuben Rideaux and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our environment is visually rich, containing a multitude of objects that can be defined by many different features, e.g. shape, colour, and motion. To navigate and interact with the environment, we must process this information efficiently. The human visual system can process information either serially or in parallel. While there is a clear timesaving benefit of parallel processing, its cost is less well understood. Consequently, the aim of this thesis is to address three key theoretical questions underlying the cost of parallel processing. The first aim was to determine how the capacity of parallel processing varies as a function of the detail of information extraction. Previous research has demonstrated that brief presentations of five and six motion signals can be differentiated; this suggests that up to five signals can be simultaneously processed. However, it is unclear how much information is being extracted, i.e. whether observers are extracting direction information from all five signals. To examine this we presented observers with multiple moving objects and evaluated their parallel processing capacity as a function of the information required to perform the task. We found that the resolution of parallel motion processing varies as a function of the information that is extracted; specifically, as information extraction becomes more detailed, the capacity to process multiple signals is reduced. The second aim was to investigate whether there is a cost to the fidelity of information that is processed in parallel. Previous research suggests that there may not be a cost associated with parallel consolidation of information from sensory to visual shortterm memory (VSTM). Here we examined this by first determining that motion direction, and possibly orientation, can be consolidated in parallel, then explicitly evaluating the cost to the fidelity of information consolidated in parallel, compared to serially. We found that there is a twofold cost associated with parallel consolidation: a reduction in resolution of encoded items due to spreading of spatial attention, and an increase in the likelihood of consolidation failure due to interference between items. The third aim was to examine whether the cost associated with parallel processing can ultimately explain its capacity. We extended our previous findings regarding the cost associated with parallel consolidation to examine whether the capacity of parallel consolidation results from biased competition, the same mechanism proposed to account for spatial attention and VSTM storage, as evidenced from the interference between items presented simultaneously. This was achieved by demonstrating that parallel consolidation performance is influenced by factors predicted by a biased competition model. Furthermore, we found evidence suggesting that the capacity may be as high as three, with increasingly poorer resolution and higher consolidation failure-rates. Together, these results demonstrate that a) parallel processing is limited by the complexity of information to be processed, b) there is a twofold cost of processing information in parallel, and c) that increasing the amount of information processed in parallel also increases this cost to the fidelity of the information and ultimately leads to the capacity of this process.

Download or read book Introduction to Psychology written by Jennifer Walinga and published by Hasanraza Ansari. This book was released on with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is designed to help students organize their thinking about psychology at a conceptual level. The focus on behaviour and empiricism has produced a text that is better organized, has fewer chapters, and is somewhat shorter than many of the leading books. The beginning of each section includes learning objectives; throughout the body of each section are key terms in bold followed by their definitions in italics; key takeaways, and exercises and critical thinking activities end each section.

Download or read book Vision written by David Marr and published by MIT Press. This book was released on 2010-07-09 with total page 429 pages. Available in PDF, EPUB and Kindle. Book excerpt: Available again, an influential book that offers a framework for understanding visual perception and considers fundamental questions about the brain and its functions. David Marr's posthumously published Vision (1982) influenced a generation of brain and cognitive scientists, inspiring many to enter the field. In Vision, Marr describes a general framework for understanding visual perception and touches on broader questions about how the brain and its functions can be studied and understood. Researchers from a range of brain and cognitive sciences have long valued Marr's creativity, intellectual power, and ability to integrate insights and data from neuroscience, psychology, and computation. This MIT Press edition makes Marr's influential work available to a new generation of students and scientists. In Marr's framework, the process of vision constructs a set of representations, starting from a description of the input image and culminating with a description of three-dimensional objects in the surrounding environment. A central theme, and one that has had far-reaching influence in both neuroscience and cognitive science, is the notion of different levels of analysis—in Marr's framework, the computational level, the algorithmic level, and the hardware implementation level. Now, thirty years later, the main problems that occupied Marr remain fundamental open problems in the study of perception. Vision provides inspiration for the continuing efforts to integrate knowledge from cognition and computation to understand vision and the brain.

Download or read book Programming Massively Parallel Processors written by David B. Kirk and published by Newnes. This book was released on 2012-12-31 with total page 519 pages. Available in PDF, EPUB and Kindle. Book excerpt: Programming Massively Parallel Processors: A Hands-on Approach, Second Edition, teaches students how to program massively parallel processors. It offers a detailed discussion of various techniques for constructing parallel programs. Case studies are used to demonstrate the development process, which begins with computational thinking and ends with effective and efficient parallel programs. This guide shows both student and professional alike the basic concepts of parallel programming and GPU architecture. Topics of performance, floating-point format, parallel patterns, and dynamic parallelism are covered in depth. This revised edition contains more parallel programming examples, commonly-used libraries such as Thrust, and explanations of the latest tools. It also provides new coverage of CUDA 5.0, improved performance, enhanced development tools, increased hardware support, and more; increased coverage of related technology, OpenCL and new material on algorithm patterns, GPU clusters, host programming, and data parallelism; and two new case studies (on MRI reconstruction and molecular visualization) that explore the latest applications of CUDA and GPUs for scientific research and high-performance computing. This book should be a valuable resource for advanced students, software engineers, programmers, and hardware engineers. - New coverage of CUDA 5.0, improved performance, enhanced development tools, increased hardware support, and more - Increased coverage of related technology, OpenCL and new material on algorithm patterns, GPU clusters, host programming, and data parallelism - Two new case studies (on MRI reconstruction and molecular visualization) explore the latest applications of CUDA and GPUs for scientific research and high-performance computing