The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Donatella Spinelli - One of the best experts on this subject based on the ideXlab platform.
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Loss of visual information in neglect: the effect of chromatic- versus Luminance-Contrast stimuli in a “what” task
Experimental Brain Research, 2005Co-Authors: Sabrina Pitzalis, Francesco Russo, Donatella SpinelliAbstract:One to four vertical bars were tachistoscopically presented at various eccentricities along the horizontal meridian to patients with right brain damage and neglect ( n =7) and to a control group of right brain damaged patients without neglect ( n =4). Luminance Contrast stimuli and isoluminant chromatic Contrast stimuli were used. The patients’ task was to report the number of bars. With Luminance stimuli the neglect patients’ discrimination in the left visual field was reduced, particularly at the most leftward position tested (ca 20°) where about 20% of the bars were omitted. The loss of information was limited to Luminance Contrast stimuli. When chromatic Contrast stimuli were used, accuracy was comparable in the two hemifields and between groups of patients. The differential pattern of results for chromatic and Luminance Contrast stimuli is consistent with the hypothesis of a selective deficit of the magno-cellular pathway in neglect.
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loss of visual information in neglect the effect of chromatic versus Luminance Contrast stimuli in a what task
Experimental Brain Research, 2005Co-Authors: Sabrina Pitzalis, Francesco Russo, Donatella SpinelliAbstract:One to four vertical bars were tachistoscopically presented at various eccentricities along the horizontal meridian to patients with right brain damage and neglect (n=7) and to a control group of right brain damaged patients without neglect (n=4). Luminance Contrast stimuli and isoluminant chromatic Contrast stimuli were used. The patients’ task was to report the number of bars. With Luminance stimuli the neglect patients’ discrimination in the left visual field was reduced, particularly at the most leftward position tested (ca 20°) where about 20% of the bars were omitted. The loss of information was limited to Luminance Contrast stimuli. When chromatic Contrast stimuli were used, accuracy was comparable in the two hemifields and between groups of patients. The differential pattern of results for chromatic and Luminance Contrast stimuli is consistent with the hypothesis of a selective deficit of the magno-cellular pathway in neglect.
Sabrina Pitzalis - One of the best experts on this subject based on the ideXlab platform.
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Loss of visual information in neglect: the effect of chromatic- versus Luminance-Contrast stimuli in a “what” task
Experimental Brain Research, 2005Co-Authors: Sabrina Pitzalis, Francesco Russo, Donatella SpinelliAbstract:One to four vertical bars were tachistoscopically presented at various eccentricities along the horizontal meridian to patients with right brain damage and neglect ( n =7) and to a control group of right brain damaged patients without neglect ( n =4). Luminance Contrast stimuli and isoluminant chromatic Contrast stimuli were used. The patients’ task was to report the number of bars. With Luminance stimuli the neglect patients’ discrimination in the left visual field was reduced, particularly at the most leftward position tested (ca 20°) where about 20% of the bars were omitted. The loss of information was limited to Luminance Contrast stimuli. When chromatic Contrast stimuli were used, accuracy was comparable in the two hemifields and between groups of patients. The differential pattern of results for chromatic and Luminance Contrast stimuli is consistent with the hypothesis of a selective deficit of the magno-cellular pathway in neglect.
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loss of visual information in neglect the effect of chromatic versus Luminance Contrast stimuli in a what task
Experimental Brain Research, 2005Co-Authors: Sabrina Pitzalis, Francesco Russo, Donatella SpinelliAbstract:One to four vertical bars were tachistoscopically presented at various eccentricities along the horizontal meridian to patients with right brain damage and neglect (n=7) and to a control group of right brain damaged patients without neglect (n=4). Luminance Contrast stimuli and isoluminant chromatic Contrast stimuli were used. The patients’ task was to report the number of bars. With Luminance stimuli the neglect patients’ discrimination in the left visual field was reduced, particularly at the most leftward position tested (ca 20°) where about 20% of the bars were omitted. The loss of information was limited to Luminance Contrast stimuli. When chromatic Contrast stimuli were used, accuracy was comparable in the two hemifields and between groups of patients. The differential pattern of results for chromatic and Luminance Contrast stimuli is consistent with the hypothesis of a selective deficit of the magno-cellular pathway in neglect.
Peter Konig - One of the best experts on this subject based on the ideXlab platform.
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Does Luminance‐Contrast contribute to a saliency map for overt visual attention?
The European journal of neuroscience, 2003Co-Authors: Wolfgang Einhauser, Peter KonigAbstract:In natural environments, humans select a subset of visual stimuli by directing their gaze to locations attended. In previous studies it has been found that at fixation points Luminance-Contrast is higher than average. This led to the hypothesis that Luminance-Contrast makes a major contribution to a saliency map of visual overt attention, consistent with a computation of stimulus saliency in early visual cortical areas. We re-evaluate this hypothesis by using natural and modified natural images to uncover the causal effects of Luminance-Contrast to human overt visual attention and: (i) we confirm that when viewing natural images, Contrasts are elevated at fixation points. This, however, only holds for low spatial frequencies and in a limited temporal window after stimulus onset; (ii) however, despite this correlation between overt attention and Luminance-Contrast, moderate modifications of Contrast in natural images do not measurably affect the selection of fixation points. Furthermore, strong local reductions of Luminance-Contrast do not repel but attract fixation; (iii) neither Contrast nor Contrast modification is correlated to fixation duration; and (iv), even the moderate Contrast modifications used fall into the physiologically relevant range, and subjects are well able to detect them in a forced choice paradigm. In summary, no causal contribution of Luminance-Contrast to a saliency map of human overt attention is detectable. In conjunction with recent results on the relation of Contrast sensitivity of neuronal activity to the level in the visual cortical hierarchy, the present study provides evidence that, for natural scenes, saliency is computed not early but late during processing.
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does Luminance Contrast contribute to a saliency map for overt visual attention
European Journal of Neuroscience, 2003Co-Authors: Wolfgang Einhauser, Peter KonigAbstract:In natural environments, humans select a subset of visual stimuli by directing their gaze to locations attended. In previous studies it has been found that at fixation points Luminance-Contrast is higher than average. This led to the hypothesis that Luminance-Contrast makes a major contribution to a saliency map of visual overt attention, consistent with a computation of stimulus saliency in early visual cortical areas. We re-evaluate this hypothesis by using natural and modified natural images to uncover the causal effects of Luminance-Contrast to human overt visual attention and: (i) we confirm that when viewing natural images, Contrasts are elevated at fixation points. This, however, only holds for low spatial frequencies and in a limited temporal window after stimulus onset; (ii) however, despite this correlation between overt attention and Luminance-Contrast, moderate modifications of Contrast in natural images do not measurably affect the selection of fixation points. Furthermore, strong local reductions of Luminance-Contrast do not repel but attract fixation; (iii) neither Contrast nor Contrast modification is correlated to fixation duration; and (iv), even the moderate Contrast modifications used fall into the physiologically relevant range, and subjects are well able to detect them in a forced choice paradigm. In summary, no causal contribution of Luminance-Contrast to a saliency map of human overt attention is detectable. In conjunction with recent results on the relation of Contrast sensitivity of neuronal activity to the level in the visual cortical hierarchy, the present study provides evidence that, for natural scenes, saliency is computed not early but late during processing.
Francesco Russo - One of the best experts on this subject based on the ideXlab platform.
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Loss of visual information in neglect: the effect of chromatic- versus Luminance-Contrast stimuli in a “what” task
Experimental Brain Research, 2005Co-Authors: Sabrina Pitzalis, Francesco Russo, Donatella SpinelliAbstract:One to four vertical bars were tachistoscopically presented at various eccentricities along the horizontal meridian to patients with right brain damage and neglect ( n =7) and to a control group of right brain damaged patients without neglect ( n =4). Luminance Contrast stimuli and isoluminant chromatic Contrast stimuli were used. The patients’ task was to report the number of bars. With Luminance stimuli the neglect patients’ discrimination in the left visual field was reduced, particularly at the most leftward position tested (ca 20°) where about 20% of the bars were omitted. The loss of information was limited to Luminance Contrast stimuli. When chromatic Contrast stimuli were used, accuracy was comparable in the two hemifields and between groups of patients. The differential pattern of results for chromatic and Luminance Contrast stimuli is consistent with the hypothesis of a selective deficit of the magno-cellular pathway in neglect.
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loss of visual information in neglect the effect of chromatic versus Luminance Contrast stimuli in a what task
Experimental Brain Research, 2005Co-Authors: Sabrina Pitzalis, Francesco Russo, Donatella SpinelliAbstract:One to four vertical bars were tachistoscopically presented at various eccentricities along the horizontal meridian to patients with right brain damage and neglect (n=7) and to a control group of right brain damaged patients without neglect (n=4). Luminance Contrast stimuli and isoluminant chromatic Contrast stimuli were used. The patients’ task was to report the number of bars. With Luminance stimuli the neglect patients’ discrimination in the left visual field was reduced, particularly at the most leftward position tested (ca 20°) where about 20% of the bars were omitted. The loss of information was limited to Luminance Contrast stimuli. When chromatic Contrast stimuli were used, accuracy was comparable in the two hemifields and between groups of patients. The differential pattern of results for chromatic and Luminance Contrast stimuli is consistent with the hypothesis of a selective deficit of the magno-cellular pathway in neglect.
Wolfgang Einhauser - One of the best experts on this subject based on the ideXlab platform.
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Does Luminance‐Contrast contribute to a saliency map for overt visual attention?
The European journal of neuroscience, 2003Co-Authors: Wolfgang Einhauser, Peter KonigAbstract:In natural environments, humans select a subset of visual stimuli by directing their gaze to locations attended. In previous studies it has been found that at fixation points Luminance-Contrast is higher than average. This led to the hypothesis that Luminance-Contrast makes a major contribution to a saliency map of visual overt attention, consistent with a computation of stimulus saliency in early visual cortical areas. We re-evaluate this hypothesis by using natural and modified natural images to uncover the causal effects of Luminance-Contrast to human overt visual attention and: (i) we confirm that when viewing natural images, Contrasts are elevated at fixation points. This, however, only holds for low spatial frequencies and in a limited temporal window after stimulus onset; (ii) however, despite this correlation between overt attention and Luminance-Contrast, moderate modifications of Contrast in natural images do not measurably affect the selection of fixation points. Furthermore, strong local reductions of Luminance-Contrast do not repel but attract fixation; (iii) neither Contrast nor Contrast modification is correlated to fixation duration; and (iv), even the moderate Contrast modifications used fall into the physiologically relevant range, and subjects are well able to detect them in a forced choice paradigm. In summary, no causal contribution of Luminance-Contrast to a saliency map of human overt attention is detectable. In conjunction with recent results on the relation of Contrast sensitivity of neuronal activity to the level in the visual cortical hierarchy, the present study provides evidence that, for natural scenes, saliency is computed not early but late during processing.
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does Luminance Contrast contribute to a saliency map for overt visual attention
European Journal of Neuroscience, 2003Co-Authors: Wolfgang Einhauser, Peter KonigAbstract:In natural environments, humans select a subset of visual stimuli by directing their gaze to locations attended. In previous studies it has been found that at fixation points Luminance-Contrast is higher than average. This led to the hypothesis that Luminance-Contrast makes a major contribution to a saliency map of visual overt attention, consistent with a computation of stimulus saliency in early visual cortical areas. We re-evaluate this hypothesis by using natural and modified natural images to uncover the causal effects of Luminance-Contrast to human overt visual attention and: (i) we confirm that when viewing natural images, Contrasts are elevated at fixation points. This, however, only holds for low spatial frequencies and in a limited temporal window after stimulus onset; (ii) however, despite this correlation between overt attention and Luminance-Contrast, moderate modifications of Contrast in natural images do not measurably affect the selection of fixation points. Furthermore, strong local reductions of Luminance-Contrast do not repel but attract fixation; (iii) neither Contrast nor Contrast modification is correlated to fixation duration; and (iv), even the moderate Contrast modifications used fall into the physiologically relevant range, and subjects are well able to detect them in a forced choice paradigm. In summary, no causal contribution of Luminance-Contrast to a saliency map of human overt attention is detectable. In conjunction with recent results on the relation of Contrast sensitivity of neuronal activity to the level in the visual cortical hierarchy, the present study provides evidence that, for natural scenes, saliency is computed not early but late during processing.
