Effects of Bottom-up and Top-down Manipulations on Visual Object Processing Across the Brain PDF Download
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Author: Lior Bugatus
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Object recognition is an incredibly important process in day to day life, and is accomplished by the human visual system automatically and effortlessly. However, this process is rarely done in isolation from goal-oriented behavior (or task) performed by the subject. Though much is known about the passive processing of objects in the visual system, far less is understood in both: (1) How tasks affect known responses to objects in visual cortex, and (2) How objects are represented in regions of higher cognition such as prefrontal cortex. Chapter I provides an overview of the existing knowledge regarding object recognition and visual processing of objects, the effects of task engagement on responses in high-level visual cortex, and what is currently known on representations of objects in prefrontal cortex. The study described in chapter II examined how the information content of object classes, or category representations, in different cortical regions changed across three qualitatively different tasks. Here we find that while responses in high-level visual cortex contain robust and task-general representations of visual categories, responses in prefrontal cortex are flexible and task-dependent, supporting their respective functional roles. The study in chapter III further dives into the effects of top-down signals, as well as bottom-up signals, in finer increments and in smaller (and independently derived) of the cortical expanses explored in the first study. The findings from this study reveal a far richer functional heterogeneity in high-level visual cortex than was previously assumed, capturing a diverse set of response profiles to bottom-up and top-down manipulations, as well as their interactions. In prefrontal cortex, no areas are engaged by purely bottom-up manipulation of stimulus, and only a small subset is engaged by the on-task condition, alluding to hypothesized mechanisms of attention. Together, these results expand what is known about the effects of task in high-level visual cortex, as well as the involvement of prefrontal cortex in object processing.
Author: Lior Bugatus
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Object recognition is an incredibly important process in day to day life, and is accomplished by the human visual system automatically and effortlessly. However, this process is rarely done in isolation from goal-oriented behavior (or task) performed by the subject. Though much is known about the passive processing of objects in the visual system, far less is understood in both: (1) How tasks affect known responses to objects in visual cortex, and (2) How objects are represented in regions of higher cognition such as prefrontal cortex. Chapter I provides an overview of the existing knowledge regarding object recognition and visual processing of objects, the effects of task engagement on responses in high-level visual cortex, and what is currently known on representations of objects in prefrontal cortex. The study described in chapter II examined how the information content of object classes, or category representations, in different cortical regions changed across three qualitatively different tasks. Here we find that while responses in high-level visual cortex contain robust and task-general representations of visual categories, responses in prefrontal cortex are flexible and task-dependent, supporting their respective functional roles. The study in chapter III further dives into the effects of top-down signals, as well as bottom-up signals, in finer increments and in smaller (and independently derived) of the cortical expanses explored in the first study. The findings from this study reveal a far richer functional heterogeneity in high-level visual cortex than was previously assumed, capturing a diverse set of response profiles to bottom-up and top-down manipulations, as well as their interactions. In prefrontal cortex, no areas are engaged by purely bottom-up manipulation of stimulus, and only a small subset is engaged by the on-task condition, alluding to hypothesized mechanisms of attention. Together, these results expand what is known about the effects of task in high-level visual cortex, as well as the involvement of prefrontal cortex in object processing.
Author: Jan Theeuwes
Publisher: Cambridge University Press
ISBN: 1108864910
Category : Psychology
Languages : en
Pages : 132
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Book Description
In this Element, a framework is proposed in which it is assumed that visual selection is the result of the interaction between top-down, bottom-up and selection-history factors. The Element discusses top-down attentional engagement and suppression, bottom-up selection by abrupt onsets and static singletons as well as lingering biases due to selection-history entailing priming, reward and statistical learning. We present an integrated framework in which biased competition among these three factors drives attention in a winner-take-all-fashion. We speculate which brain areas are likely to be involved and how signals representing these three factors feed into the priority map which ultimately determines selection.
Author: Michael Dambacher
Publisher: Universitätsverlag Potsdam
ISBN: 3869560592
Category : Language Arts & Disciplines
Languages : en
Pages : 262
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Book Description
In reading, word frequency is commonly regarded as the major bottom-up determinant for the speed of lexical access. Moreover, language processing depends on top-down information, such as the predictability of a word from a previous context. Yet, however, the exact role of top-down predictions in visual word recognition is poorly understood: They may rapidly affect lexical processes, or alternatively, influence only late post-lexical stages. To add evidence about the nature of top-down processes and their relation to bottom-up information in the timeline of word recognition, we examined influences of frequency and predictability on event-related potentials (ERPs) in several sentence reading studies. The results were related to eye movements from natural reading as well as to models of word recognition. As a first and major finding, interactions of frequency and predictability on ERP amplitudes consistently revealed top-down influences on lexical levels of word processing (Chapters 2 and 4). Second, frequency and predictability mediated relations between N400 amplitudes and fixation durations, pointing to their sensitivity to a common stage of word recognition; further, larger N400 amplitudes entailed longer fixation durations on the next word, a result providing evidence for ongoing processing beyond a fixation (Chapter 3). Third, influences of presentation rate on ERP frequency and predictability effects demonstrated that the time available for word processing critically co-determines the course of bottom-up and top-down influences (Chapter 4). Fourth, at a near-normal reading speed, an early predictability effect suggested the rapid comparison of top-down hypotheses with the actual visual input (Chapter 5). The present results are compatible with interactive models of word recognition assuming that early lexical processes depend on the concerted impact of bottom-up and top-down information. We offered a framework that reconciles the findings on a timeline of word recognition taking into account influences of frequency, predictability, and presentation rate (Chapter 4).
Author: Gregory Hickok
Publisher: W. W. Norton & Company
ISBN: 0393244164
Category : Science
Languages : en
Pages : 251
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Book Description
An essential reconsideration of one of the most far-reaching theories in modern neuroscience and psychology. In 1992, a group of neuroscientists from Parma, Italy, reported a new class of brain cells discovered in the motor cortex of the macaque monkey. These cells, later dubbed mirror neurons, responded equally well during the monkey’s own motor actions, such as grabbing an object, and while the monkey watched someone else perform similar motor actions. Researchers speculated that the neurons allowed the monkey to understand others by simulating their actions in its own brain. Mirror neurons soon jumped species and took human neuroscience and psychology by storm. In the late 1990s theorists showed how the cells provided an elegantly simple new way to explain the evolution of language, the development of human empathy, and the neural foundation of autism. In the years that followed, a stream of scientific studies implicated mirror neurons in everything from schizophrenia and drug abuse to sexual orientation and contagious yawning. In The Myth of Mirror Neurons, neuroscientist Gregory Hickok reexamines the mirror neuron story and finds that it is built on a tenuous foundation—a pair of codependent assumptions about mirror neuron activity and human understanding. Drawing on a broad range of observations from work on animal behavior, modern neuroimaging, neurological disorders, and more, Hickok argues that the foundational assumptions fall flat in light of the facts. He then explores alternative explanations of mirror neuron function while illuminating crucial questions about human cognition and brain function: Why do humans imitate so prodigiously? How different are the left and right hemispheres of the brain? Why do we have two visual systems? Do we need to be able to talk to understand speech? What’s going wrong in autism? Can humans read minds? The Myth of Mirror Neurons not only delivers an instructive tale about the course of scientific progress—from discovery to theory to revision—but also provides deep insights into the organization and function of the human brain and the nature of communication and cognition.
Author: Stephen M. Kosslyn
Publisher: MIT Press
ISBN: 9780262611244
Category : Psychology
Languages : en
Pages : 532
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Book Description
This long-awaited work by prominent Harvard psychologist Stephen Kosslyn integrates a twenty-year research program on the nature of high-level vision and mental imagery. Image and Brain marshals insights and empirical results from computer vision, neuroscience, and cognitive science to develop a general theory of visual mental imagery, its relation to visual perception, and its implementation in the human brain. It offers a definitive resolution to the long-standing debate about the nature of the internal representation of visual mental imagery. Kosslyn reviews evidence that perception and representation are inextricably linked, and goes on to show how "quasi-pictorial" events in the brain are generated, interpreted, and used in cognition. The theory is tested with brain-scanning techniques that provide stronger evidence than has been possible in the past. Known for his work in high-level vision, one of the most empirically successful areas of experimental psychology, Kosslyn uses a highly interdisciplinary approach. He reviews and integrates an extensive amount of literature in a coherent presentation, and reports a wide range of new findings using a host of techniques. A Bradford Book
Author: Nelson Cowan
Publisher: Oxford University Press
ISBN: 0195344251
Category : Psychology
Languages : en
Pages : 342
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Book Description
Attention and Memory brings together and assesses past and present research on information processing, to formulate a model of this entire system.
Author: Bessel A. Van der Kolk
Publisher: Penguin Books
ISBN: 0143127748
Category : Medical
Languages : en
Pages : 466
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Book Description
Originally published by Viking Penguin, 2014.
Author: Bradley S. Gibson
Publisher:
ISBN:
Category : Psychology
Languages : en
Pages : 276
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Book Description
The notion that certain mental or physical events can capture attention has been one of the most enduring topics in the study of attention owing to the importance of understanding how goal-directed and stimulus-driven processes interact in perception and cognition. Despite the clear theoretical and applied importance of attentional capture, a broad survey of this field suggests that the term "capture" means different things to different people. In some cases, it refers to covert shifts of spatial attention, in others involuntary saccades, and in still others general disruption of processing by irrelevant stimuli. The properties that elicit "capture" can also range from abruptly onset or moving lights, to discontinuities in textures, to unexpected tones, to emotionally valenced words or pictures, to directional signs and symbols. Attentional capture has been explored in both the spatial and temporal domains as well as the visual and auditory modalities. There are also a number of different theoretical perspectives on the mechanisms underlying "capture" (both functional and neurophysiological) and the level of cognitive control over capture. This special issue provides a sampling of the diversity of approaches, domains, and theoretical perspectives that currently exist in the study of attentional capture. Together, these contributions should help evaluate the degree to which attentional capture represents a unitary construct that reflects fundamental theoretical principles and mechanisms of the mind.
Author: Jess Hartcher-O'Brien
Publisher: Frontiers Media SA
ISBN: 2889451933
Category :
Languages : en
Pages : 141
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Book Description
The integration of information from various sensory modalities influences behaviour. It can induce behavioural benefits such as faster reaction times and enhanced detection of noisy signals but may also produce illusions, all of which have been characterized by specific neuronal signatures. Yet, while these effects of multisensory integration are largely accepted, the role of attention in this process is still the object of intense debate. On the one hand, it has been suggested that attention may guide multisensory integration in a top-down fashion by selection of specific inputs to be integrated out of the plethora of information in our environment. On the other hand, there is evidence that integration could occur in a bottom-up manner, based on temporal and spatial correlations, and outside the focus of attention. An extreme example is the multisensory enhancement of neural responses in anesthetised animals. Attention itself is not a unitary construct, and may refer to a range of different selection mechanisms. Therefore, the interplay between attention and multisensory integration can take many forms which explain, in part, the diversity of findings and the disputes in the literature. The goal of this Research Topic is to help clarify the picture by trying to answer the following questions from various perspectives: Under which circumstances does multisensory integration take place without attention?, and, When does attention determine the fate of multisensory integration?
Author: Wolfgang Prinz
Publisher: MIT Press
ISBN: 0262312980
Category : Science
Languages : en
Pages : 467
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Book Description
An overview of today's diverse theoretical and methodological approaches to action and the relationship of action and cognition. The emerging field of action science is characterized by a diversity of theoretical and methodological approaches that share the basic functional belief that evolution has optimized cognitive systems to serve the demands of action. This book brings together the constitutive approaches of action science in a single source, covering the relation of action to such cognitive functions as perception, attention, memory, and volition. Each chapter offers a tutorial-like description of a major line of inquiry, written by a leading scientist in the field. Taken together, the chapters reflect a dynamic and rapidly growing field and provide a forum for comparison and possible integration of approaches. After discussing core questions about how actions are controlled and learned, the book considers ecological approaches to action science; neurocogntive approaches to action understanding and attention; developmental approaches to action science; social actions, including imitation and joint action; and the relationships between action and the conceptual system (grounded cognition) and between volition and action. An emerging discipline depends on a rich and multifaceted supply of theoretical and methodological approaches. The diversity of perspectives offered in this book will serve as a guide for future explorations in action science. Contributors Lawrence W. Barsalou, Miriam Beisert, Valerian Chambon, Thomas Goschke, Patrick Haggard, Arvid Herwig, Herbert Heuer, Cecilia Heyes, Bernhard Hommel, Glyn W. Humphreys, Richard B. Ivry, Markus Kiefer, Günther Knoblich, Sally A. Linkenauger, Janeen D. Loehr, Peter J. Marshall, Andrew N. Meltzoff, Wolfgang Prinz, Dennis R. Proffitt, Giacomo Rizzolatti, David A. Rosenbaum, Natalie Sebanz, Corrado Sinigaglia, Sandra Sülzenbrück, Jordan A. Taylor, Michael T. Turvey, Claes von Hofsten, Rebecca A. Williamson
