Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Spatial Feature And Temporal Attentional Mechanisms In Visual Motion Processing
Download Spatial Feature And Temporal Attentional Mechanisms In Visual Motion Processing full books in PDF, epub, and Kindle. Read online Spatial Feature And Temporal Attentional Mechanisms In Visual Motion Processing ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Spatial, Feature and Temporal Attentional Mechanisms in Visual Motion Processing by :
Download or read book Spatial, Feature and Temporal Attentional Mechanisms in Visual Motion Processing written by and published by . This book was released on 2012 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: The three projects documented in this thesis investigated the role of three forms of attention in visual processing. Spatial, feature-based and temporal attention. The spatial and feature-based attentional characteristics were studied by conducting extracellular recordings from neurons of area MT and MSTd of macaque visual cortex. While the role of temporal attention was studied in a human psychophysics project. In the physiology projects we first defined the tuning characteristics of neurons from area MT and MSTd for two stimulus dimensions, namely spiral motion stimuli (SMS) and linear mo...
Book Synopsis Effects of Attention on Visual Motion Processing by : Amira Amina Rezec
Download or read book Effects of Attention on Visual Motion Processing written by Amira Amina Rezec and published by . This book was released on 2004 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamics of Visual Motion Processing by : Guillaume S. Masson
Download or read book Dynamics of Visual Motion Processing written by Guillaume S. Masson and published by Springer Science & Business Media. This book was released on 2009-12-02 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Motion processing is an essential piece of the complex brain machinery that allows us to reconstruct the 3D layout of objects in the environment, to break camouflage, to perform scene segmentation, to estimate the ego movement, and to control our action. Although motion perception and its neural basis have been a topic of intensive research and modeling the last two decades, recent experimental evidences have stressed the dynamical aspects of motion integration and segmentation. This book presents the most recent approaches that have changed our view of biological motion processing. These new experimental evidences call for new models emphasizing the collective dynamics of large population of neurons rather than the properties of separate individual filters. Chapters will stress how the dynamics of motion processing can be used as a general approach to understand the brain dynamics itself.
Book Synopsis Investigating Mechanisms of Spatial and Temporal Selective Visual Attention by : Mary E. Smith
Download or read book Investigating Mechanisms of Spatial and Temporal Selective Visual Attention written by Mary E. Smith and published by . This book was released on 2017 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selective attention in vision undoubtedly uses many different types of mechanisms to achieve better processing of behaviorally relevant visual information. The present dissertation inspects two such possible mechanisms. The first proposed mechanism is through selective spatial attention. We proposed that "attentional control" regions of the brain send selective attention signals that relate to the differential attentional modulation measured in visual cortex, corresponding to the attended and ignored sides of visual space. We find, surprisingly, that the BOLD signal of attentional control regions do not appear to code for selective spatial attention in this manner. fMRI signals therefore appear to prioritize general arousal effects of attention more so than the types of attentional control signals that frontoparietal regions send to early visual cortex. The second proposed mechanism is through sampling visual information through time. It is hypothesized that intrinsic neural oscillations represent inhibitory waves of cortical processing ability, in which subjects are more or less able to detect visual stimuli depending on the phase of [alpha] oscillations in the brain. We used a paradigm involving visual entrainment; this paradigm has been used in the past to support the "pulsed inhibition of [alpha]" hypothesis. We find that the behavioral effects of this paradigm cannot strongly be supported by the pulsed inhibition of [alpha] because the neural effects of visual entrainment are transient and do not carry over into the target period.
Book Synopsis Visual Attention Mechanisms by : Virginio Cantoni
Download or read book Visual Attention Mechanisms written by Virginio Cantoni and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the Fifth International School on Neural Networks "E.R. Caianiello" on Visual Attention MechaProceedings of the Fifth International School on Neural Networks "E.R. Caianiello" on Visual Attention Mechanisms, held 23-28 October 2000 in Vietri sul Mare, Italy.nisms, held 23-28 October 2000 in Vietri sul Mare, Italy. The book covers a number of broad themes relevant to visual attention, ranging from computer vision to psychology and physiology of vision. The main theme of the book is the attention processes of vision systems and it aims to point out the analogies and the divergences of biological vision with the frameworks introduced by computer scientists in artificial vision.
Book Synopsis Investigating Attentional Mechanisms Underlying Feature Integration: Evidence from Within- and Cross-modality Behavioral and Eye Movement Studies by :
Download or read book Investigating Attentional Mechanisms Underlying Feature Integration: Evidence from Within- and Cross-modality Behavioral and Eye Movement Studies written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work is aimed at contributing to a better understanding of the spatial and temporal mechanisms underlying integration of feature signals within and between sensory modalities under search conditions. Furthermore, it investigates the respective contribution of feature signals in the elaboration of memory for the search context in a complex visual search task. Chapter 2 presents an introduction to selection and integration of information coming from one or more sensory modality, and discusses recent research on the topic. Chapter 3 concerns the temporal organization of visual feature integration (color, orientation, and motion), somewhat neglected by current cognitive models focusing primarily on spatial mechanisms of feature integration. To evaluate the relative temporal contribution of feature signals defining the to-be-found object, an adapted version of the visual search paradigm (in which an odd object has to be detected among distractor objects) involving redundantly defined items (i.e., objects differing from their neighbors in more than one feature, e.g., a red vertical bar among green horizontal bars) was used, in which all items are identical at the search display onset and the target item is revealed after feature changes of one of the searched items; feature changes are separated by variable time intervals. This procedure allows using the race model inequality (RMI; Miller, 1986) to differentiate two different integration models. Both assume that feature signals are processed independently and in parallel, but diverge concerning the mechanisms that generate the response associated to the target detection. A first model postulates that redundancy gains, referring to the faster detection of redundantly defined targets (compared to singly defined targets), result from a parallel race of independent signals, whose winner triggers the response (race model; Raab, 1962), whereas an alternative account assumes that both features contribute to the respo.
Book Synopsis Visual Spatial Attention by : Lana Haynes
Download or read book Visual Spatial Attention written by Lana Haynes and published by Novinka Books. This book was released on 2016 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many events in our daily lives require that we allocate attentional resources towards relevant information in the environment. However, we are constantly presented with more information than we can possibly attend to at any given moment. Visual spatial attention is the prioritization of visual processing to a particular spatial region in one's environment, and is therefore an important component of attention (more broadly construed) and information-processing. Once a region of space has been selected by visual spatial attention, the objects and features within that region can be processed. In this book, Chapter One examines visual spatial attention and its functional role in a variety of cognitive tasks. Chapter Two reviews the different ways in which the various mechanisms of selective attention have been cortically and otherwise classified into low and high levels of processing and to disentangle some of the confusion that may have arisen as a result of inconsistent usage of terminology and concepts in the field. The last chapter discusses studies which use computer simulations to estimate the effect of noise correlation upon the performance benefit gained from cues.
Book Synopsis The Effects of Feature-based Attention on Perception by : Xiaohua Zhuang
Download or read book The Effects of Feature-based Attention on Perception written by Xiaohua Zhuang and published by . This book was released on 2010 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: Feature-based attention is one of the mechanisms that can facilitate the processing of many aspects of our visual perception. A variety of paradigms were employed in the current dissertation to further investigate how feature-based attention modulates motion perception, visual search and temporal processing of stimuli. The first set of experiments aimed to explore the effects of feature-based attention on the processing of motion speed and motion direction separately. Speed and direction discrimination tasks were used in separate experiments. Results showed that feature-based attention has more dramatic influence on direction perception than on speed perception. This may be taken as evidence that humans are more sensitive to motion speed change than to motion direction change. The second set of experiments was designed to study how performance in color-orientation conjunctive searches changes when observers attend to a pre-cued location, or a pre-cued feature (color or orientation), as well as the temporal characteristics of these precue effects. Color (sensory and symbolic) and location precues improved search performance. The magnitude of improvement did not vary as the inter-stimulus interval (ISI) changed for color and location cues. The sensory color and location cues exhibited their effect in directing visual search as early as 0 ms of ISI. However, orientation precue did not facilitate nor inhibit the search processing. These results may imply that color is a better feature to base the segmentation processing on and thereby facilitate the visual search processing. The third set of experiments explored the existence of feature-based attentional prior-entry effect, which refers to the hypothesis that attended objects are perceived prior to unattended ones. Temporal order judgment (TOJ) and simultaneity judgment (SJ) tasks were employed to test this hypothesis. Prior-entry effect for objects with attended feature was found in TOJ task, the most frequently used paradigm in the literature to claim the spatial prior-entry effect, but the effect was absent in the SJ task. This could be due to a second-order response bias in the TOJ task, or to the fact that the SJ task is not as sensitive as the TOJ task.
Book Synopsis Visual Attention and Cortical Circuits by : Jochen Braun
Download or read book Visual Attention and Cortical Circuits written by Jochen Braun and published by MIT Press. This book was released on 2001 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: An attempt to derive a comprehensive theory of attention from both neurobiological and psychological data.
Book Synopsis Visual Motion Perception and Visual Information Processing by :
Download or read book Visual Motion Perception and Visual Information Processing written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the domain of motion perception, the implementation of a new pedestal paradigm and some critical subsidiary paradigms (interocular displays, stimulus superpositions with varying phases and directions, alternating-feature stimuli, and attentional manipulations) enabled the measurement in isolation of the spatial and temporal characteristics of the three main human motion perception mechanisms (the so-called first-, second, and third-order systems). The first- and second-order systems, known previously, were now shown to exist in duplicate, having a primarily left eye and a primarily right eye computational branch. Additionally, a purely binocular (third-order) motion mechanism was discovered and measured.
Book Synopsis Neurobiology of Attention by : Laurent Itti
Download or read book Neurobiology of Attention written by Laurent Itti and published by Elsevier. This book was released on 2005-03-31 with total page 757 pages. Available in PDF, EPUB and Kindle. Book excerpt: A key property of neural processing in higher mammals is the ability to focus resources by selectively directing attention to relevant perceptions, thoughts or actions. Research into attention has grown rapidly over the past two decades, as new techniques have become available to study higher brain function in humans, non-human primates, and other mammals. Neurobiology of Attention is the first encyclopedic volume to summarize the latest developments in attention research.An authoritative collection of over 100 chapters organized into thematic sections provides both broad coverage and access to focused, up-to-date research findings. This book presents a state-of-the-art multidisciplinary perspective on psychological, physiological and computational approaches to understanding the neurobiology of attention. Ideal for students, as a reference handbook or for rapid browsing, the book has a wide appeal to anybody interested in attention research. * Contains numerous quick-reference articles covering the breadth of investigation into the subject of attention* Provides extensive introductory commentary to orient and guide the reader* Includes the most recent research results in this field of study
Book Synopsis Visual Motion Perception, Visual Attention and Visual Information Processing by :
Download or read book Visual Motion Perception, Visual Attention and Visual Information Processing written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuing work on the three-systems-theory of visual motion perception: (I) Isoluminant chromatic motion is perceived by and only by the third-order motion system. (2) New illusion. Cancelling salience modulation in the third-order motion system causes brightly colored moving red-green gratings to appear to be motionless (motion standstill illusion) that gives considerable insight into the mechanisms of object perception. (3) A prediction that motion could be used to provide amplification of apparent contrast was verified, with amplifications>5x. (4) Amplification procedures were used to construct purified stimuli to stimulate each motion system individually, and (5) to measure the amplification produced by selective attention to a feature. (6) Developed computational models oi attentional amplification of features and of the movement dynamics of spatial attention. The spatial attentional mode was investigated with a new paradigm (gating spatial attention) to enable measurements of iconic memory uncontaminated by attention dynamics and to demonstrate that a new attention "window' open concurrently at all points within the window. (7) The spatial attention model predicts 90% of the variance in a huge data set (approximately 500 points per observer from>20,000 trials) and encompasses the major attention paradigms. (All items plus more are fully described in publications.).
Book Synopsis Neural Mechanisms of Spatial Attention by : Ashley Royston
Download or read book Neural Mechanisms of Spatial Attention written by Ashley Royston and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Elucidating the neural bases of selective attention continues to be a key challenge for psychologists, vision scientists and cognitive neuroscientists. It also represents an essential aim in translational efforts to measure, treat and prevent visual and attentional deficits, to improve teaching and learning, and to tailor automated situational awareness and alerting systems to human capabilities. Past human functional magnetic resonance imaging (fMRI) and electroencephalographic (EEG) studies, as well as animal electrophysiological studies, have provided considerable information about the temporal properties, neuroanatomical substrates, and cellular- and synaptic-level mechanisms underlying attention. Despite substantial convergence in the mechanisms of attention revealed by these different approaches, there remain significant unresolved quandaries in the scientific literature. In particular, it is currently debated whether attention can influence neural activity during the initial feedforward wave of visual processing in human primary visual cortex (V1). FMRI in humans and cellular recordings in monkeys both suggest spatial attention can influence afferent sensory processing in V1. In sharp contrast, however, such effects of attention have not been reliably reported for human EEG recordings; the short-latency C1 component of the visually evoked event-related potential (ERP) that is generated in V1 is typically not affected by selective attention. Given the fMRI findings and the animal studies, what can explain this discrepancy? FMRI activations are tied to slow changes in cerebral hemodynamics that cannot distinguish between attention effects on incoming signals and activations due to longer-latency feedback activation of V1 from higher stages of visual processing—therefore, fMRI evidence is equivocal regarding whether attention-related V1 activations represent modulations of feedforward or feedback V1 activity. However, human and animal electrophysiology both provide the temporal resolution to distinguished between initial afferent volleys and feedback activity, making it difficult to reconcile the positive findings in monkeys and the negative findings in humans. The overarching hypothesis of this dissertation is that differences in the methods and paradigms between monkey and human studies could contribute to the differences in attention effects in V1. Specifically, monkey studies typically use continuous stimulation that is arguably more similar to natural vision than the punctate stimulation paradigms (e.g., trial-by-trial spatial cuing) often used in humans to study the effects of attention on sensory processing. Ongoing stimulation may trigger attention-related feedback signals from higher areas onto V1 that might not arise, or might not be observable, when simple, single, isolated stimuli are used. To investigate whether the nature of ongoing visual stimulation may account for some of the discrepancies reported in the literature, this dissertation examines human ERPs recorded during selective attention in six variations of a novel spatial attention task that builds on a paradigm successfully used to reveal V1 attention effects in nonhuman primates. Using this task, significant effects of spatial attention were observed on the amplitude of the C1 ERP in humans (Chapter 2). The addition of high-resolution eye gaze monitoring, however, demonstrated that small, systematic deviations of eye gaze in the direction of the cue hemifield likely contributed to the Chapter 2 finding, and when data from trials with deviations of eye gaze were eliminated, no attentional modulation on the C1 ERP remained (Chapter 3). Therefore, the main hypothesis that stimulus-triggered feedback attentional modulation of V1 signals should be observed as changes in C1 ERP amplitude, was not supported. Although the present findings do not explain the differences between spatial attention effects in monkey and human V1, they do provide additional support for the model that spatial attention effects observed using fMRI in humans is likely not the result of changes in input signal processing in V1, but instead reflects later recurrent activation of V1 that serves other computational purposes.
Book Synopsis Neural Mechanisms of Visual Segmentation Using Motion and Depth Cues in Cortical Area MT by : Venkta Lakshmi Anjani Chakrala
Download or read book Neural Mechanisms of Visual Segmentation Using Motion and Depth Cues in Cortical Area MT written by Venkta Lakshmi Anjani Chakrala and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our dynamic world requires us to discern objects in complex environments to effectively interact with our surroundings. Our visual system has the remarkable ability to seamlessly segment objects from each other, unmatched by current machine vision systems, that enables us to understand visual scenes and guides actions. In natural vision, visual motion combined with other features like depth and cognitive abilities like attention is important to segment objects. Visual motion processing is widely studied at both perceptual and physiological levels. However, the neural mechanisms underlying the segmentation of multiple objects aided by motion combined with other features like depth and spatial location are not fully understood. The goal of this dissertation is to elucidate the neural mechanisms underlying the segmentation of multiple objects using motion direction, speed, depth (binocular disparity), and spatial location. Toward this, in chapter 2, I determined the neural representation of multiple objects, that differed in depth and motion direction and investigated the effect of selective attention on this representation. We designed a novel motion discrimination task, in which macaque monkeys selectively attended to one of two moving surfaces separated in depth. The task was paired with electrophysiological recordings from the middle temporal area (MT), known for its selectivity to visual motion and binocular disparity. Our results suggest that to represent multiple surfaces with different depths and motion direction, MT neurons leverage their preference to the binocular disparity of the constituent surfaces, so that the information about the two motion directions is distributed over neuronal subgroups defined by their disparity preferences (near and far-preferred neurons). Selective attention to one disparity enhanced the representation of the attended surface and its motion direction. In chapter 3, I investigated how MT neurons encoded two spatially separated stimuli moving at different speeds. Akin to chapter 2, we found that the MT neurons' spatial and speed preferences to single motion were preserved in their responses to two spatially separated speeds, which might help in their segmentation. Together, our results elucidate prevailing neural strategies of encoding multiple visual stimuli, and how the visual system exploits spatial cues either two-dimensional or three-dimensional, together with motion cues to segment multiple objects.
Book Synopsis Cognitive Electrophysiology of Attention by : George R. Mangun
Download or read book Cognitive Electrophysiology of Attention written by George R. Mangun and published by Academic Press. This book was released on 2013-08-31 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cognitive Electrophysiology of Attention explores the fundamental mechanisms of attention and related cognitive functions from cognitive neuroscience perspectives. Attention is an essential cognitive ability that enables humans to process and act upon relevant information while ignoring distracting information, and the capacity to focus attention is at the core of mental functioning. Understanding the neural bases of human attention remains a key challenge for neuroscientists and psychologists, and is essential for translational efforts to treat attentional deficits in a variety of neurological and psychiatric disorders. Cognitive electrophysiology is at the center of a multidisciplinary approach that involves the efforts of psychologists, neuroscientists, neuropsychologists, psychiatrists, and neurologists to identify basic brain mechanisms and develop translational approaches to improve mental health. This edited volume is authored by leading investigators in the field and discusses methods focused on electrophysiological recordings in humans, including electroencephalography (EEG) and event-related potential (ERP) methods, and also incorporates evidence from functional magnetic resonance imaging (fMRI). Cognitive Electrophysiology of Attention illuminates specific models about attentional mechanisms in vision, audition, multisensory integration, memory, and semantic processing in humans. Provides an exhaustive overview of attention processes, going from normal functioning to the pathological, and using a combination of methodological tools An important reference for electrophysiology researchers looking at underlying attention processes rather than the methods themselves Enables researchers across a broad range of cognitive-process and methodological specialties to stay current on particular hypotheses, findings, and methods Edited and authored by the worldwide leaders in the field, affording the broadest, most expert coverage available
Book Synopsis The Cognitive Neurosciences, fifth edition by : Michael S. Gazzaniga
Download or read book The Cognitive Neurosciences, fifth edition written by Michael S. Gazzaniga and published by MIT Press. This book was released on 2014-10-24 with total page 1187 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fifth edition of a work that defines the field of cognitive neuroscience, with entirely new material that reflects recent advances in the field. Each edition of this classic reference has proved to be a benchmark in the developing field of cognitive neuroscience. The fifth edition of The Cognitive Neurosciences continues to chart new directions in the study of the biological underpinnings of complex cognition—the relationship between the structural and physiological mechanisms of the nervous system and the psychological reality of the mind. It offers entirely new material, reflecting recent advances in the field. Many of the developments in cognitive neuroscience have been shaped by the introduction of novel tools and methodologies, and a new section is devoted to methods that promise to guide the field into the future—from sophisticated models of causality in brain function to the application of network theory to massive data sets. Another new section treats neuroscience and society, considering some of the moral and political quandaries posed by current neuroscientific methods. Other sections describe, among other things, new research that draws on developmental imaging to study the changing structure and function of the brain over the lifespan; progress in establishing increasingly precise models of memory; research that confirms the study of emotion and social cognition as a core area in cognitive neuroscience; and new findings that cast doubt on the so-called neural correlates of consciousness.
Book Synopsis High-level Motion Processing by : Takeo Watanabe
Download or read book High-level Motion Processing written by Takeo Watanabe and published by MIT Press. This book was released on 1998 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contributors to this book focus on such key aspects of motion processing as interaction and integration between locally measured motion units, structure from motion, heading in an optical flow, and second-order motion. They also discuss the interaction of motion processing with other high-level visual functions such as surface representation and attention.
