Hemifield Asymmetries In The Spatial Distribution Of Selective Attention
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Hemifield Asymmetries In The Spatial Distribution Of Selective Attention
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Author : Afroditi Panagopoulos
language : en
Publisher:
Release Date : 2014
Hemifield Asymmetries In The Spatial Distribution Of Selective Attention written by Afroditi Panagopoulos and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Visual attention is involved in many everyday tasks, such as finding one’s shoes, driving, or looking for a face in a crowd. Often attention must be allocated or split onto more than one location. Yet how does the visual system accomplish this, and what cost does it have in terms of performance in visual tasks? This dissertation reports the results of an investigation of the claim that attention could be allocated to two or more non-contiguous locations simultaneously. This study uses a technique, which to the best of my knowledge, has not been used by other investigators studying the splitting of attention. The stimulus used in the current thesis consisted of four possible cue locations, with each potential location located in 45 degree increments (45, 135, 225, 315 degrees) at the same eccentricity. Experiment 1 replicated the results of previous attention studies, but using the new cueing paradigm. The results showed that the spotlight of attention could change location when multiple potential locations are present. The advantage of the new paradigm is the possibility of cueing different locations within and between visual hemifields. This was explored in Experiments 2 and 3, to examine the role of hemispheric asymmetries in the debate over multifocal attention. Specifically, two locations were cued in Experiment 2, and Experiment 3 examined the differences of splitting the attentional beam within and across hemifields. Finally, Experiment 4 investigated the effect of cueing all four locations at the same time. The results from the current thesis confirm that observers can allocate attention to two or more simultaneous locations, without observing any attentional enhancement coming from the in-between cued locations. However, these results stemmed from attending to two locations across hemifields. The present thesis provides more evidence in support of the ability to split attention, and describes the impact that multifocal attention plays in visual perception.
The Spatial Distribution Of Attention
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Author : Thomas John Lacki
language : en
Publisher:
Release Date : 1982
The Spatial Distribution Of Attention written by Thomas John Lacki and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1982 with categories.
Top Down Influences On Selective Attention Across The Extended Visual Field
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Author : Jing Feng
language : en
Publisher:
Release Date : 2011
Top Down Influences On Selective Attention Across The Extended Visual Field written by Jing Feng and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The research focuses on the role of top-down influences on selective attention across the attentional visual field. The attentional visual field is the subset of the visual field in which attentional processes take place. The size of the attentional visual field is relatively large compared to the areas considered by most empirical studies of visual attention to date. Three possible forms of top-down influence are examined: 1) the expectation of the size of the area in which the target is likely to occur; 2) the expectation of the direction in which the target is likely to occur; and 3) existing unconscious bias in the spatial distribution of attention. Results from Experiment 1 suggest that participants modify the size of the attended area according to their expectation of the location of the target. Experiment 2 demonstrates that focus of attention can be oriented toward the expected target direction. Experiment 3 reveals that, even when no conscious control is involved, the distribution of attention is biased toward certain areas. Theoretical considerations are discussed, including the introduction of a simple statistical model to assist in conceptualizing the modifications of the distribution of attention over the attentional visual field. Practical applications of the results are also discussed.
Spatial Distribution And Hemispheric Asymmetry Of Electrically Evoked Experiental Phenomena In The Human Brain
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Author : Michal Andelman
language : en
Publisher:
Release Date : 2019
Spatial Distribution And Hemispheric Asymmetry Of Electrically Evoked Experiental Phenomena In The Human Brain written by Michal Andelman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
Spatial Effects In Visual Selective Attention
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Author : Inge Fryklund Bennett
language : en
Publisher:
Release Date : 1971
Spatial Effects In Visual Selective Attention written by Inge Fryklund Bennett and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with Human information processing categories.
In many visual selection experiments, Ss view displays of colored letters and numbers. They are instructed to attend to some stimulus dimension (e.g., row location, color, class) and are cued to report the items indicated by one value (e.g., top row, red color) on that dimension. Accuracy is always highest for row report. Since the items cued by row are spatially connected and easily coded for memory, and those cued by color or class spatially scattered and difficult to code, it cannot be concluded that row selection is more efficient than, say, color selection. In these experiments, selection criterion is held constant, and the spatial arrangement of the targets is varied. In Exp. I, Ss reported the identities of the 5 red letters appearing in a 5 x 5 matrix. Four types of target arrangements were tested. Four backgrounds, varying in degree of confusability with the targets, were combined factorially with the four target patterns. The effects of pattern and background and their interaction were highly significant. It is suggested that spatial arrangement per se is not crucial; rather the target pattern serves to control the degree of background interference. Experiments II and III were detection analogs of the Letters background similarity condition of Exp. I. The Ss had to report whether an A or a T appeared among the red letters. The results for the pattern types were similar, indicating that there are spatial constraints on visual processing at a level low enough to be tapped in a detection task. (Author).
Hemispheric Asymmetry
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Author : Gina Geffen
language : en
Publisher:
Release Date : 1972
Hemispheric Asymmetry written by Gina Geffen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1972 with Perception categories.
Gradients And Ranges Of Visually Selective Attention Based On Location Objects Color And Size
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Author : William S. Bush
language : en
Publisher:
Release Date : 2012
Gradients And Ranges Of Visually Selective Attention Based On Location Objects Color And Size written by William S. Bush and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Attention categories.
Two interesting properties of the distribution of spatially selective attention have been noted in the behavioral and electrophysiological literature. First, there is a graded field of attention that expands from the center of the attended area. Second, the size of the attended area can be adjusted to be either larger or smaller in order to match the demands of the current task. Five event-related potential (ERP) studies are presented that extend these findings in several important ways; 1) The time frame of these two distribution properties is different. Results are consistent with a two stage model of spatial attention in which visual processing is initially enhanced for all stimuli presented near the center of the attended area as indexed by the amplitude of the first negative peak in the waveform (N1). Subsequently, the effects of narrowing or expanding the attentional field to the relevant size affects visual processing as indexed by the amplitude of the second negative peak (N2). 2) Object boundaries had limited impact on either the spread of the initial gradient of spatial selection or the scale of attention. 3) When selecting visual stimuli for attentive processing based on features such as color and size there is also a gradient of facilitation, but the impact of this graded selection on visual processing is not observed until later in processing, and is indexed by the amplitude of the selection negativity (SN). Furthermore, similar to the lack of interaction between object boundaries and the range of cued locations, the gradients of feature-based selection are not affected by the range of cued features.
Spatial And Non Spatial Aspects Of Neglect
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Author : Konstantinos Priftis
language : en
Publisher: Frontiers Media SA
Release Date : 2015-07-10
Spatial And Non Spatial Aspects Of Neglect written by Konstantinos Priftis and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-07-10 with Neurosciences. Biological psychiatry. Neuropsychiatry categories.
Neglect is one of the most impressive neuropsychological disorder, for both its theoretical and clinical relevance. Besides being very common and disabling, it is highly informative for understanding normal cognitive functioning. The hallmark of neglect is the failure to attend to the contralesional hemispace. However, several studies have recently highlighted that additional deficits, not attributable to a spatial bias, are associated to the impaired contralesional hemispace processing. Moreover, manifestations of neglect tend to be particularly heterogeneous and often dissociate according to the spatial domain being investigated (e.g., body space, space within reaching, space beyond reaching, imaginal space). Heterogeneity in neglect patients also means that dissociations across different tasks in a single patient are more the rule than the exception. Evidence suggests that some of these dissociations can be readily explained by taking into account the amount of available attentional resources as a major determinant for the presence and the severity of neglect. There is no doubt that neglect patients provide a wealth of information about the functioning of systems subserving attentional orienting and spatial processing. Moreover, their performance also show that some non-spatial deficits are tightly coupled with more classic contralesional spatial deficits. It seems however still unclear to what extent these non-spatial deficits are an intrinsic characteristic of neglect or whether they are to be considered unspecific effects of the often massive brain lesions suffered by the patients. From the clinical point of view, neglect is a disorder that dramatically affects patients and their caregivers, because it severely limits the individuals’ autonomy and motor recovery after brain damage. For these reasons neglect is a disorder that is worth rehabilitating. To be effective, neglect rehabilitation should be based on the knowledge of what cognitive aspects are impaired and it should be focused on improving daily-life performance. For these reasons, it is also important to detect and quantify subtle forms of neglect.
Neuroscience Letters
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Author :
language : en
Publisher:
Release Date : 2005
Neuroscience Letters written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Neurology categories.
Lateralization And Cognitive Systems
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Author : Sebastian Ocklenburg
language : en
Publisher: Frontiers Media SA
Release Date : 2015-02-24
Lateralization And Cognitive Systems written by Sebastian Ocklenburg and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-02-24 with Psychology categories.
Left-right asymmetries of structure and function are a common organization principle in the brains of humans and non-human vertebrates alike. While there are inherently asymmetric systems such as the human language system or the song system of songbirds, the impact of structural or functional asymmetries on perception, cognition and behavior is not necessarily limited to these systems. For example, performance in experimental paradigms that assess executive functions such as inhibition, planning or action monitoring is influenced by information processing in the bottom-up channel. Depending on the type of stimuli used, one hemisphere can be more efficient in processing than the other and these functional cerebral asymmetries have been shown to modulate the efficacy of executive functions via the bottom-up channel. We only begin to understand the complex neuronal mechanisms underlying this interaction between hemispheric asymmetries and cognitive systems. Therefore, it is the aim of this Research Topics to further elucidate how structural or functional hemispheric asymmetries modulate perception, cognition and behavior in the broadest sense.