The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Susana T L Chung - One of the best experts on this subject based on the ideXlab platform.
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sensory factors limiting horizontal and vertical visual span for Letter Recognition
Journal of Vision, 2014Co-Authors: Deyue Yu, Gordon E Legge, Gunther Wagoner, Susana T L ChungAbstract:Reading speed for English text is slower for text oriented vertically than horizontally. Yu, Park, Gerold, and Legge (2010) showed that slower reading of vertical text is associated with a smaller visual span (the number of Letters recognized with high accuracy without moving the eyes). Three possible sensory determinants of the size of the visual span are: resolution (decreasing acuity at Letter positions farther from the midline), mislocations (uncertainty about the relative position of Letters in strings), and crowding (interference from flanking Letters in recognizing the target Letter). In the present study, we asked which of these factors is most important in determining the size of the visual span, and likely in turn in determining the horizontal/vertical difference in reading when Letter size is above the critical print size for reading. We used a decomposition analysis to represent constraints due to resolution, mislocations, and crowding as losses in information transmitted (in bits) about Letter Recognition. Across vertical and horizontal conditions, crowding accounted for 75% of the loss in information, mislocations accounted for 19% of the loss, and declining acuity away from fixation accounted for only 6%. We conclude that crowding is the major factor limiting the size of the visual span, and that the horizontal/vertical difference in the size of the visual span is associated with stronger crowding along the vertical midline.
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size or spacing which limits Letter Recognition in people with age related macular degeneration
Vision Research, 2014Co-Authors: Susana T L ChungAbstract:Abstract Recent evidence suggests a double dissociation of size and spacing limit on Letter Recognition—it is limited by size in the fovea and critical spacing in the normal periphery. Here, we evaluated whether size or spacing limits Letter Recognition in people with age-related macular degeneration (AMD) who must use their peripheral vision. We measured the size threshold for recognizing lowercase Letters presented alone, or flanked by two Letters at various center-to-center nominal Letter spacings (multiples of Letter size) for 11 observers with AMD. For comparison, similar measurements were obtained at 5° and 10° eccentricity in the nasal and lower visual fields in three older adults with normal vision. Single-Letter size thresholds were worse for observers with AMD than at comparable retinal locations in the normal periphery. For flanked Letters, size threshold improved with larger nominal spacing up to the critical spacing, beyond which size threshold was unaffected by the flankers. Seven AMD observers had a nominal critical spacing between 1.25× and 1.80×, values close to those in the normal fovea, suggesting that their Letter Recognition is size-limited; two had a nominal critical spacing of 3–4×, values close to those in the normal periphery, implying that their Letter Recognition is limited by spacing; and another two had a nominal critical spacing of ∼2.3×, implying that their Letter Recognition is limited by both size and spacing. The wide range of nominal critical spacings observed in our AMD observers may reflect the degree of completeness of their adaptation process to vision loss.
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Letter Recognition and reading speed in peripheral vision benefit from perceptual learning
Vision Research, 2004Co-Authors: Susana T L Chung, Gordon E Legge, Singhang CheungAbstract:Visual-span profiles are plots of Letter-Recognition accuracy as a function of Letter position left or right of the midline. Previously, we have shown that contraction of these profiles in peripheral vision can account for slow reading speed in peripheral vision. In this study, we asked two questions: (1) can we modify visual-span profiles through training on Letter-Recognition, and if so, (2) are these changes accompanied by changes in reading speed? Eighteen normally sighted observers were randomly assigned to one of three groups: training at 10° in the upper visual field, training at 10° in the lower visual field and a no-training control group. We compared observers’ characteristics of reading (maximum reading speed and critical print size) and visual-span profiles (peak amplitude and bits of information transmitted) before and after training, and at trained and untrained retinal locations (10° upper and lower visual fields). Reading speeds were measured for six print sizes at each retinal location, using the rapid serial visual presentation paradigm. Visual-span profiles were measured using a trigram Letter-Recognition task, for a Letter size equivalent to 1.4 × the critical print size for reading. Training consisted of the repeated measurement of 20 visual-span profiles (over four consecutive days) in either the upper or lower visual field. We also tracked the changes in performance in a sub-group of observers for up to three months following training. We found that the visual-span profiles can be expanded (bits of information transmitted increased by 6 bits) through training with a Letter-Recognition task, and that there is an accompanying increase (41%) in the maximum reading speed. These improvements transferred, to a large extent, from the trained to an untrained retinal location, and were retained, to a large extent, for at least three months following training. Our results are consistent with the view that the visual span is a bottleneck on reading speed, but a bottleneck that can be increased with practice.
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psychophysics of reading xx linking Letter Recognition to reading speed in central and peripheral vision
Vision Research, 2001Co-Authors: Gordon E Legge, Stephen J Mansfield, Susana T L ChungAbstract:Abstract Our goal is to link spatial and temporal properties of Letter Recognition to reading speed for text viewed centrally or in peripheral vision. We propose that the size of the visual span — the number of Letters recognizable in a glance — imposes a fundamental limit on reading speed, and that shrinkage of the visual span in peripheral vision accounts for slower peripheral reading. In Experiment 1, we estimated the size of the visual span in the lower visual field by measuring RSVP (rapid serial visual presentation) reading times as a function of word length. The size of the visual span decreased from at least 10 Letters in central vision to 1.7 Letters at 15° eccentricity, in good agreement with the corresponding reduction of reading speed measured by Chung and coworkers (Chung, S. T. L., Mansfield, J. S., & Legge, G. E. (1998). Psychophysics of reading. XVIII. The effect of print size on reading speed in normal peripheral vision. Vision Research, 38, 2949–2962). In Exp. 2, we measured Letter Recognition for trigrams (random strings of three Letters) as a function of their position on horizontal lines passing through fixation (central vision) or displaced downward into the lower visual field (5, 10 and 20°). We also varied trigram presentation time. We used these data to construct visual-span profiles of Letter accuracy versus Letter position. These profiles were used as input to a parameter-free model whose output was RSVP reading speed. A version of this model containing a simple lexical-matching rule accounted for RSVP reading speed in central vision. Failure of this version of the model in peripheral vision indicated that people rely more on lexical inference to support peripheral reading. We conclude that spatiotemporal characteristics of the visual span limit RSVP reading speed in central vision, and that shrinkage of the visual span results in slower reading in peripheral vision.
Karin H. James - One of the best experts on this subject based on the ideXlab platform.
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Visual–motor symbol production facilitates Letter Recognition in young children
Reading and Writing, 2018Co-Authors: Deborah Zemlock, Sophia Vinci-booher, Karin H. JamesAbstract:Previous research has suggested that handwriting Letters may be an important exerciser to facilitate early Letter understanding. Experimental studies to date, however, have not investigated whether this effect is general to any visual–motor experience or specific to handwriting Letters. In the present work, we addressed this issue by testing Letter knowledge using three measures in preschool children before and after a school-based intervention. Participants were divided into four training groups (Letter-writing, digit-writing, Letter-viewing, digit-viewing) that either wrote Letters or digits or viewed Letters or digits, twice a week for 6 weeks. We hypothesized that the visual–motor experience of handwriting Letters or digits would improve Letter knowledge more than viewing experience and that this effect would not be specific to training with Letters. Our results demonstrated that the writing groups improved in Letter Recognition—one component of Letter knowledge—significantly more than the viewing groups. The Letter-writing group did not improve significantly more than the digit-writing group. These results suggest that visual–motor practice with any symbol could lead to increases in Letter Recognition. We interpret this novel finding as suggesting that any handwriting will increase Letter Recognition in part because it facilitates gains in visual–motor coordination.
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visual motor symbol production facilitates Letter Recognition in young children
Reading and Writing, 2018Co-Authors: Deborah Zemlock, Sophia Vincibooher, Karin H. JamesAbstract:Previous research has suggested that handwriting Letters may be an important exerciser to facilitate early Letter understanding. Experimental studies to date, however, have not investigated whether this effect is general to any visual–motor experience or specific to handwriting Letters. In the present work, we addressed this issue by testing Letter knowledge using three measures in preschool children before and after a school-based intervention. Participants were divided into four training groups (Letter-writing, digit-writing, Letter-viewing, digit-viewing) that either wrote Letters or digits or viewed Letters or digits, twice a week for 6 weeks. We hypothesized that the visual–motor experience of handwriting Letters or digits would improve Letter knowledge more than viewing experience and that this effect would not be specific to training with Letters. Our results demonstrated that the writing groups improved in Letter Recognition—one component of Letter knowledge—significantly more than the viewing groups. The Letter-writing group did not improve significantly more than the digit-writing group. These results suggest that visual–motor practice with any symbol could lead to increases in Letter Recognition. We interpret this novel finding as suggesting that any handwriting will increase Letter Recognition in part because it facilitates gains in visual–motor coordination.
Gabriel A De Erausquin - One of the best experts on this subject based on the ideXlab platform.
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a n400 erp study in Letter Recognition after passive tactile stimulation training in blind children and sighted controls
Restorative Neurology and Neuroscience, 2019Co-Authors: Tomas Ortiz, Laura Ortizteran, Agustin Turrero, Joaquin Pochbroto, Gabriel A De ErausquinAbstract:BACKGROUND: We previously demonstrated that using a sensory substitution device (SSD) for one week, tactile stimulation results in faster activation of lateral occipital complex in blind children than in seeing controls. OBJECTIVE: We used long-term haptic tactile stimulation training with an SSD to test if it results in stable cross-modal reassignment of visual pathways after six months, to provide high level processing of tactile semantic content. METHODS: We enrolled 12 blind and 12 sighted children. The SSD transforms images to a stimulation matrix in contact with the dominant hand. Subjects underwent twice-daily training sessions, 5 days/week for six months. Children were asked to describe line orientation, name Letters, and read words. ERP sessions were performed at baseline and 6 months to analyze the N400 ERP component and reaction times (RT). N400 sources were estimated with Low Resolution Electromagnetic Tomography (LORETA). SPM8 was used to make population-level inferences. RESULTS: We found no group differences in RTs, accuracy of identifications, N400 latencies or distributions with the line task at 1 week or at 6 months. RTs on the Letter Recognition task were also similar. After 6 months, behavioral training increased accurate Letter identification in both seeing and blind children (Chi 2 = 11906.934, p = 0.000), but the increase was larger in blind children (Chi 2 = 8.272, p = 0.004). Behavioral training shifted peak N400 amplitude to left occipital and bilateral parietal cortices in blind children, but to left precentral and postcentral and bilateral occipital cortices in sighted controls. CONCLUSIONS: Blind children learn to recognize SSD-delivered Letters better than seeing controls and had greater N400 amplitude in the occipital region. To the best of our knowledge, our results provide the first published example of standard Letter Recognition (not Braille) by children with blindness using a tactile delivery system.
Ronald A Cole - One of the best experts on this subject based on the ideXlab platform.
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spoken Letter Recognition
Neural Information Processing Systems, 1990Co-Authors: Mark Fanty, Ronald A ColeAbstract:Through the use of neural network classifiers and careful feature selection, we have achieved high-accuracy speaker-independent spoken Letter Recognition. For isolated Letters, a broad-category segmentation is performed Location of segment boundaries allows us to measure features at specific locations in the signal such as vowel onset, where important information resides. Letter classification is performed with a feed-forward neural network. Recognition accuracy on a test set of 30 speakers was 96%. Neural network classifiers are also used for pitch tracking and broad-category segmentation of Letter strings. Our research has been extended to Recognition of names spelled with pauses between the Letters. When searching a database of 50,000 names, we achieved 95% first choice name retrieval. Work has begun on a continuous Letter classifier which does frame-by-frame phonetic classification of spoken Letters.
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NIPS - Spoken Letter Recognition
1990Co-Authors: Mark Fanty, Ronald A ColeAbstract:Through the use of neural network classifiers and careful feature selection, we have achieved high-accuracy speaker-independent spoken Letter Recognition. For isolated Letters, a broad-category segmentation is performed Location of segment boundaries allows us to measure features at specific locations in the signal such as vowel onset, where important information resides. Letter classification is performed with a feed-forward neural network. Recognition accuracy on a test set of 30 speakers was 96%. Neural network classifiers are also used for pitch tracking and broad-category segmentation of Letter strings. Our research has been extended to Recognition of names spelled with pauses between the Letters. When searching a database of 50,000 names, we achieved 95% first choice name retrieval. Work has begun on a continuous Letter classifier which does frame-by-frame phonetic classification of spoken Letters.
Rabia Jafri - One of the best experts on this subject based on the ideXlab platform.
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electronic braille blocks a tangible interface based application for teaching braille Letter Recognition to very young blind children
International Conference on Computers for Handicapped Persons, 2014Co-Authors: Rabia JafriAbstract:A software solution for teaching Braille Letter Recognition to very young blind children is presented which allows them to interact with the computer by manipulating NFC-tag embedded blocks with Braille Letters embossed on their sides. Braille Letter Recognition is taught and reinforced through various exercises and games and auditory feedback is provided via a speech interface. By embedding interactivity into physical blocks, our system provides the best of both worlds: the manipulation and exploration of physical objects in accordance with the sensory dependence and developmental needs of young children and the exploitation of the power of digital technology to extend and enhance the learning process taking place through traditional exploratory play. Furthermore, this is a cost-effective solution and does not require children to have previous experience with computers. This system can be easily adapted in the future to teach other concepts such as Braille numbers, shape or texture Recognition.
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ICCHP (2) - Electronic Braille Blocks: A Tangible Interface-Based Application for Teaching Braille Letter Recognition to Very Young Blind Children
Lecture Notes in Computer Science, 2014Co-Authors: Rabia JafriAbstract:A software solution for teaching Braille Letter Recognition to very young blind children is presented which allows them to interact with the computer by manipulating NFC-tag embedded blocks with Braille Letters embossed on their sides. Braille Letter Recognition is taught and reinforced through various exercises and games and auditory feedback is provided via a speech interface. By embedding interactivity into physical blocks, our system provides the best of both worlds: the manipulation and exploration of physical objects in accordance with the sensory dependence and developmental needs of young children and the exploitation of the power of digital technology to extend and enhance the learning process taking place through traditional exploratory play. Furthermore, this is a cost-effective solution and does not require children to have previous experience with computers. This system can be easily adapted in the future to teach other concepts such as Braille numbers, shape or texture Recognition.
