The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Gordon E Legge - One of the best experts on this subject based on the ideXlab platform.
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common constraints limit korean and english character recognition in peripheral vision
Journal of Vision, 2018Co-Authors: Miyoung Kwon, Gordon E LeggeAbstract:The Visual Span refers to the number of adjacent characters that can be recognized in a single glance. It is viewed as a sensory bottleneck in reading for both normal and clinical populations. In peripheral vision, the Visual Span for English characters can be enlarged after training with a letter-recognition task. Here, we examined the transfer of training from Korean to English characters for a group of bilingual Korean native speakers. In the pre- and posttests, we measured Visual Spans for Korean characters and English letters. Training (1.5 hours × 4 days) consisted of repetitive Visual-Span measurements for Korean trigrams (strings of three characters). Our training enlarged the Visual Spans for Korean single characters and trigrams, and the benefit transferred to untrained English symbols. The improvement was largely due to a reduction of within-character and between-character crowding in Korean recognition, as well as between-letter crowding in English recognition. We also found a negative correlation between the size of the Visual Span and the average pattern complexity of the symbol set. Together, our results showed that the Visual Span is limited by common sensory (crowding) and physical (pattern complexity) factors regardless of the language script, providing evidence that the Visual Span reflects a universal bottleneck for text recognition.
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linking crowding Visual Span and reading
Journal of Vision, 2017Co-Authors: Gordon E LeggeAbstract:The Visual Span is hypothesized to be a sensory bottleneck on reading speed with crowding thought to be the major sensory factor limiting the size of the Visual Span. This proposed linkage between crowding, Visual Span, and reading speed is challenged by the finding that training to read crowded letters reduced crowding but did not improve reading speed (Chung, 2007). Here, we examined two properties of letter-recognition training that may influence the transfer to improved reading: the spatial arrangement of training stimuli and the presence of flankers. Three groups of nine young adults were trained with different configurations of letter stimuli at 10° in the lower Visual field: a flanked-local group (flanked letters localized at one position), a flanked-distributed group (flanked letters distributed across different horizontal locations), and an isolated-distributed group (isolated and distributed letters). We found that distributed training, but not the presence of flankers, appears to be necessary for the training benefit to transfer to increased reading speed. Localized training may have biased attention to one specific, small area in the Visual field, thereby failing to improve reading. We conclude that the Visual Span represents a sensory bottleneck on reading, but there may also be an attentional bottleneck. Reducing the impact of crowding can enlarge the Visual Span and can potentially facilitate reading, but not when adverse attentional bias is present. Our results clarify the association between crowding, Visual Span, and reading.
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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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effect of pattern complexity on the Visual Span for chinese and alphabet characters
Journal of Vision, 2014Co-Authors: Hui Wang, Gordon E LeggeAbstract:The Visual Span for reading is the number of letters that can be recognized without moving the eyes and is hypothesized to impose a sensory limitation on reading speed. Factors affecting the size of the Visual Span have been studied using alphabet letters. There may be common constraints applying to recognition of other scripts. The aim of this study was to extend the concept of the Visual Span to Chinese characters and to examine the effect of the greater complexity of these characters. We measured Visual Spans for Chinese characters and alphabet letters in the central vision of bilingual subjects. Perimetric complexity was used as a metric to quantify the pattern complexity of binary character images. The Visual Span tests were conducted with four sets of stimuli differing in complexity—lowercase alphabet letters and three groups of Chinese characters. We found that the size of Visual Spans decreased with increasing complexity, ranging from 10.5 characters for alphabet letters to 4.5 characters for the most complex Chinese characters studied. A decomposition analysis revealed that crowding was the dominant factor limiting the size of the Visual Span, and the amount of crowding increased with complexity. Errors in the spatial arrangement of characters (mislocations) had a secondary effect. We conclude that pattern complexity has a major effect on the size of the Visual Span, mediated in large part by crowding. Measuring the Visual Span for Chinese characters is likely to have high relevance to understanding Visual constraints on Chinese reading performance.
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sensory and cognitive influences on the training related improvement of reading speed in peripheral vision
Journal of Vision, 2013Co-Authors: Yingchen He, Gordon E Legge, Deyue YuAbstract:Reading speed in normal peripheral vision is slow but can be increased through training on a letter-recognition task. The aim of the present study is to investigate the sensory and cognitive factors responsible for this improvement. The Visual Span is hypothesized to be a sensory bottleneck limiting reading speed. Three sensory factors—letter acuity, crowding, and mislocations (errors in the spatial order of letters)—may limit the size of the Visual Span. Reading speed is also influenced by cognitive factors including the utilization of information from sentence context. We conducted a perceptual training experiment to investigate the roles of these factors. Training consisted of four daily sessions of trigram letter-recognition trials at 10° in the lower Visual field. Subjects' Visual-Span profiles and reading speeds were measured in pre- and posttests. Effects of the three sensory factors were isolated through a decomposition analysis of the Visual Span profiles. The impact of sentence context was indexed by context gain, the ratio of reading speeds for ordered and unordered text. Following training, Visual Spans increased in size by 5.4 bits of information transmitted, and reading speeds increased by 45%. Training induced a substantial reduction in the magnitude of crowding (4.8 bits) and a smaller reduction for mislocations (0.7 bits), but no change in letter acuity or context gain. These results indicate that the basis of the training-related improvement in reading speed is a large reduction in the interfering effect of crowding and a small reduction of mislocation errors.
Susana T L Chung - One of the best experts on this subject based on the ideXlab platform.
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Reading in the presence of macular disease: a mini-review.
eScholarship University of California, 2020Co-Authors: Susana T L ChungAbstract:PURPOSE:Reading is vital to full participation in modern society. To millions of people suffering from macular disease that results in a central scotoma, reading is difficult and inefficient, rendering reading as the primary goal for most patients seeking low vision rehabilitation. The goals of this review paper are to summarize the dependence of reading speed on several key Visual and typographical factors and the current methods or technologies for improving reading performance for people with macular disease. IMPORTANT FINDINGS:In general, reading speed for people with macular disease depends on print size, text contrast, size of the Visual Span, temporal processing of letters and oculomotor control. Attempts at improving reading speed by reducing the crowding effect between letters, words or lines; or optimizing properties of typeface such as the presence of serifs or stroke-width thickness proved to be futile, with any improvement being modest at best. Currently, the most promising method to improve reading speed for people with macular disease is training, including perceptual learning or oculomotor training. SUMMARY:The limitation on reading speed for people with macular disease is likely to be multi-factorial. Future studies should try to understand how different factors interact to limit reading speed, and whether different methods could be combined to produce a much greater benefit
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Music-reading expertise modulates the Visual Span for English letters but not Chinese characters.
eScholarship University of California, 2019Co-Authors: Susana T L Chung, Hsiao, Janet HAbstract:Recent research has suggested that the Visual Span in stimulus identification can be enlarged through perceptual learning. Since both English and music reading involve left-to-right sequential symbol processing, music-reading experience may enhance symbol identification through perceptual learning particularly in the right Visual field (RVF). In contrast, as Chinese can be read in all directions, and components of Chinese characters do not consistently form a left-right structure, this hypothesized RVF enhancement effect may be limited in Chinese character identification. To test these hypotheses, here we recruited musicians and nonmusicians who read Chinese as their first language (L1) and English as their second language (L2) to identify music notes, English letters, Chinese characters, and novel symbols (Tibetan letters) presented at different eccentricities and Visual field locations on the screen while maintaining central fixation. We found that in English letter identification, significantly more musicians achieved above-chance performance in the center-RVF locations than nonmusicians. This effect was not observed in Chinese character or novel symbol identification. We also found that in music note identification, musicians outperformed nonmusicians in accuracy in the center-RVF condition, consistent with the RVF enhancement effect in the Visual Span observed in English-letter identification. These results suggest that the modulation of music-reading experience on the Visual Span for stimulus identification depends on the similarities in the perceptual processes involved
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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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can reading specific training stimuli improve the effect of perceptual learning on peripheral reading speed
Vision Research, 2012Co-Authors: Jeanbaptiste Bernard, Amit Arunkumar, Susana T L ChungAbstract:Abstract In a previous study, Chung, Legge, and Cheung (2004) showed that training using repeated presentation of trigrams (sequences of three random letters) resulted in an increase in the size of the Visual Span (number of letters recognized in a glance) and reading speed in the normal periphery. In this study, we asked whether we could optimize the benefit of trigram training on reading speed by using trigrams more specific to the reading task (i.e., trigrams frequently used in the English language) and presenting them according to their frequencies of occurrence in normal English usage and observers’ performance. Averaged across seven observers, our training paradigm (4 days of training) increased the size of the Visual Span by 6.44 bits, with an accompanied 63.6% increase in the maximum reading speed, compared with the values before training. However, these benefits were not statistically different from those of Chung, Legge, and Cheung (2004) using a random-trigram training paradigm. Our findings confirm the possibility of increasing the size of the Visual Span and reading speed in the normal periphery with perceptual learning, and suggest that the benefits of training on letter recognition and maximum reading speed may not be linked to the types of letter strings presented during training.
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reading speed in the peripheral Visual field of older adults does it benefit from perceptual learning
Vision Research, 2010Co-Authors: Singhang Cheung, Gordon E Legge, Susana T L ChungAbstract:Enhancing reading ability in peripheral vision is important for the rehabilitation of people with central-Visual-field loss from age-related macular degeneration (AMD). Previous research has shown that perceptual learning, based on a trigram letter-recognition task, improved peripheral reading speed among normally-sighted young adults (Chung, Legge, & Cheung, 2004). Here we ask whether the same happens in older adults in an age range more typical of the onset of AMD. Eighteen normally-sighted subjects, aged 55-76years, were randomly assigned to training or control groups. Visual-Span profiles (plots of letter-recognition accuracy as a function of horizontal letter position) and RSVP reading speeds were measured at 10 degrees above and below fixation during pre- and post-tests for all subjects. Training consisted of repeated measurements of Visual-Span profiles at 10 degrees below fixation, in four daily sessions. The control subjects did not receive any training. Perceptual learning enlarged the Visual Spans in both trained (lower) and untrained (upper) Visual fields. Reading speed improved in the trained field by 60% when the trained print size was used. The training benefits for these older subjects were weaker than the training benefits for young adults found by Chung et al. Despite the weaker training benefits, perceptual learning remains a potential option for low-vision reading rehabilitation among older adults.
Randi Starrfelt - One of the best experts on this subject based on the ideXlab platform.
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Visual attention in posterior stroke and relations to alexia
Neuropsychologia, 2016Co-Authors: Anders Petersen, Signe Vangkilde, C Fabricius, Helle K Iversen, Tzvetelina Delfi, Randi StarrfeltAbstract:Impaired Visual attention is common following strokes in the territory of the middle cerebral artery, particularly in the right hemisphere, while attentional effects of more posterior lesions are less clear. Commonly, such deficits are investigated in relation to specific syndromes like Visual agnosia or pure alexia. The aim of this study was to characterize Visual processing speed and apprehension Span following posterior cerebral artery (PCA) stroke. In addition, the relationship between these attentional parameters and single word reading is investigated, as previous studies have suggested that reduced Visual speed and Span may explain pure alexia. Eight patients with unilateral PCA strokes (four left hemisphere, four right hemisphere) were selected on the basis of lesion location, rather than the presence of any Visual symptoms. Visual attention was characterized by a whole report paradigm allowing for hemifield-specific measurements of processing speed and apprehension Span. All patients showed reductions in Visual Span contralateral to the lesion site, and four patients showed bilateral reductions in Visual Span despite unilateral lesions (2L; 2R). Six patients showed selective deficits in Visual Span, though processing speed was unaffected in the same field (ipsi- or contralesionally). Only patients with right hemifield reductions in Visual Span were impaired in reading, and this could follow either right or left lateralized stroke and was irrespective of Visual field impairments. In conclusion, Visual Span may be affected bilaterally by unilateral PCA-lesions. Reductions in Visual Span may also be confined to one hemifield, and may be affected in spite of preserved Visual processing speed. Furthermore, reduced Span in the right Visual field seems to be related to reading impairment in this group, regardless of lesion lateralization.
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Too Little, Too Late: Reduced Visual Span and Speed Characterize Pure Alexia
Cerebral Cortex, 2009Co-Authors: Randi Starrfelt, Thomas Habekost, Alexander P. LeffAbstract:Whether normal word reading includes a stage of Visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general Visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central Visual field was impaired in all patients. Visual apprehension Span was also reduced for both letters and digits in all patients. The only cortical region lesioned across all 4 patients was the left fusiform gyrus, indicating that this region subserves a function broader than letter or word identification. We suggest that a seemingly pure disorder of reading can arise due to a general reduction of Visual speed and Span, and explain why this has a disproportionate impact on word reading while recognition of other Visual stimuli are less obviously affected.
Singhang Cheung - One of the best experts on this subject based on the ideXlab platform.
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reading speed in the peripheral Visual field of older adults does it benefit from perceptual learning
Vision Research, 2010Co-Authors: Singhang Cheung, Gordon E Legge, Susana T L ChungAbstract:Enhancing reading ability in peripheral vision is important for the rehabilitation of people with central-Visual-field loss from age-related macular degeneration (AMD). Previous research has shown that perceptual learning, based on a trigram letter-recognition task, improved peripheral reading speed among normally-sighted young adults (Chung, Legge, & Cheung, 2004). Here we ask whether the same happens in older adults in an age range more typical of the onset of AMD. Eighteen normally-sighted subjects, aged 55-76years, were randomly assigned to training or control groups. Visual-Span profiles (plots of letter-recognition accuracy as a function of horizontal letter position) and RSVP reading speeds were measured at 10 degrees above and below fixation during pre- and post-tests for all subjects. Training consisted of repeated measurements of Visual-Span profiles at 10 degrees below fixation, in four daily sessions. The control subjects did not receive any training. Perceptual learning enlarged the Visual Spans in both trained (lower) and untrained (upper) Visual fields. Reading speed improved in the trained field by 60% when the trained print size was used. The training benefits for these older subjects were weaker than the training benefits for young adults found by Chung et al. Despite the weaker training benefits, perceptual learning remains a potential option for low-vision reading rehabilitation among older adults.
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reading speed in the peripheral Visual field of older adults does it benefit from perceptual learning
Vision Research, 2010Co-Authors: Deyue Yu, Singhang Cheung, Gordon E Legge, Susana T L ChungAbstract:Abstract Enhancing reading ability in peripheral vision is important for the rehabilitation of people with central-Visual-field loss from age-related macular degeneration (AMD). Previous research has shown that perceptual learning, based on a trigram letter-recognition task, improved peripheral reading speed among normally-sighted young adults ( Chung, Legge, & Cheung, 2004 ). Here we ask whether the same happens in older adults in an age range more typical of the onset of AMD. Eighteen normally-sighted subjects, aged 55–76 years, were randomly assigned to training or control groups. Visual-Span profiles (plots of letter-recognition accuracy as a function of horizontal letter position) and RSVP reading speeds were measured at 10° above and below fixation during pre- and post-tests for all subjects. Training consisted of repeated measurements of Visual-Span profiles at 10° below fixation, in four daily sessions. The control subjects did not receive any training. Perceptual learning enlarged the Visual Spans in both trained (lower) and untrained (upper) Visual fields. Reading speed improved in the trained field by 60% when the trained print size was used. The training benefits for these older subjects were weaker than the training benefits for young adults found by Chung et al. Despite the weaker training benefits, perceptual learning remains a potential option for low-vision reading rehabilitation among older adults.
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relationship between Visual Span and reading performance in age related macular degeneration
Vision Research, 2008Co-Authors: Allen M Y Cheong, Gordon E Legge, Singhang Cheung, M G Lawrence, M A RuffAbstract:Purpose Visual-Span profiles are plots of letter-recognition accuracy as a function of letter position left and right of the point of fixation. Legge, Mansfield, and Chung [Legge, G. E., Mansfield, J. S., & Chung, S. T. L. (2001). Psychophysics of reading—XX. Linking letter recognition to reading speed in central and peripheral vision. Vision Research, 41(6), 725–743] proposed that reduced size of the Visual Span is a spatial factor limiting reading speed in patients with age-related macular degeneration (AMD). We have recently shown that a temporal property of letter recognition—the exposure time required for a high level of accuracy—is also a factor limiting reading speed in AMD [Cheong, A. M. Y., Legge, G. E., Lawrence, M. G., Cheung, S. H., & Ruff, M. (2007). Relationship between slow Visual processing and reading speed in people with macular degeneration. Vision Research, 47, 2943–2965]. We measured the Visual-Span profiles of AMD subjects and assessed the relationship of the spatial and temporal properties of these profiles to reading speed. Methods Thirteen AMD subjects and 11 age-matched normals were tested. Visual-Span profiles were measured by using the trigram letter-recognition method described by Legge et al. (2001). Each individual’s temporal threshold for letter recognition (80% accuracy criterion) was used as the exposure time for measuring the Visual-Span profile. Size of the Visual Span was computed as the area under the profile in bits of information transmitted. The information transfer rate in bits per second was defined as the Visual-Span size in bits divided by the exposure time in sec. Results AMD Visual-Span sizes were substantially smaller (median of 23.9 bits) than normal Visual-Span sizes in central vision (median of 40.8 bits, p < .01). For the nine AMD subjects with eccentric fixation, the Visual-Span sizes (median of 20.6 bits) were also significantly smaller than Visual Spans of normal controls at 10° below fixation in peripheral vision (median of 29.0 bits, p = .01). Information transfer rate for the AMD subjects (median of 29.5 bits/s) was significantly slower than that for the age-matched normals at both central and peripheral vision (median of 411.7 and 290.5 bits/s respectively, ps < .01). Information transfer rates were more strongly correlated with reading speed than the size of the Visual Span, and explained 36% of the variance in AMD reading speed. Conclusion Both Visual-Span size and information transfer rate were significantly impaired in the AMD subjects compared with age-matched normals. Information transfer rate, representing the combined effects of a reduced Visual Span and slower temporal processing of letters, was a better predictor of reading speed in AMD subjects than was the size of the Visual Span.
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the case for the Visual Span as a sensory bottleneck in reading
Journal of Vision, 2007Co-Authors: Gordon E Legge, Susana T L Chung, Singhang Cheung, Hye Won Lee, Daniel P OwensAbstract:The Visual Span for reading is the number of letters, arranged horizontally as in text, that can be recognized reliably without moving the eyes. The Visual-Span hypothesis states that the size of the Visual Span is an important factor that limits reading speed. From this hypothesis, we predict that changes in reading speed as a function of character size or contrast are determined by corresponding changes in the size of the Visual Span. We tested this prediction in two experiments in which we measured the size of the Visual Span and reading speed on groups of five subjects as a function of either character size or character contrast. We used a "trigram method" for characterizing the Visual Span as a profile of letter-recognition accuracy as a function of distance left and right of the midline (G. E. Legge, J. S. Mansfield, & S. T. L. Chung, 2001). The area under this profile was taken as an operational measure of the size of the Visual Span. Reading speed was measured with the Rapid Serial Visual Presentation (RSVP) method. We found that the size of the Visual Span and reading speed showed the same qualitative dependence on character size and contrast, reached maximum values at the same critical points, and exhibited high correlations at the level of individual subjects. Additional analysis of data from four studies provides evidence for an invariant relationship between the size of the Visual Span and RSVP reading speed; an increase in the Visual Span by one letter is associated with a 39% increase in reading speed. Our results confirm the Visual-Span hypothesis and provide a theoretical framework for understanding the impact of stimulus attributes, such as contrast and character size, on reading speed. Evidence for the Visual Span as a determinant of reading speed implies the existence of a bottom-up, sensory limitation on reading, distinct from attentional, motor, or linguistic influences.
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effect of letter spacing on Visual Span and reading speed
Journal of Vision, 2007Co-Authors: Singhang Cheung, Gordon E Legge, Susana T L ChungAbstract:S. T. L. Chung (2002) has shown that rapid serial Visual presentation (RSVP) reading speed varies with letter spacing, peaking near the standard letter spacing for text and decreasing for both smaller and larger spacings. In this study, we tested the hypothesis that the dependence of reading speed on letter spacing is mediated by the size of the Visual Span-the number of letters recognized with high accuracy without moving the eyes. If so, the size of the Visual Span and reading speed should show a similar dependence on letter spacing. We tested this prediction for RSVP reading and asked whether it generalizes to the reading of blocks of text requiring eye movements. We measured Visual-Span profiles and reading speeds as a function of letter spacing. Visual-Span profiles, measured with trigrams (strings of three random letters), are plots of letter-recognition accuracy as a function of letter position left or right of fixation. Size of the Visual Span was quantified by a measure of the area under the Visual-Span profile. Reading performance was measured using two presentation methods: RSVP and flashcard (a short block of text on four lines). We found that the size of the Visual Span and the reading speeds measured by the two presentation methods showed a qualitatively similar dependence on letter spacing and that they were highly correlated. These results are consistent with the view that the size of the Visual Span is a primary Visual factor that limits reading speed.
Eyal M Reingold - One of the best experts on this subject based on the ideXlab platform.
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controlling the spotlight of attention Visual Span size and flexibility in schizophrenia
Neuropsychologia, 2011Co-Authors: Ava Elahipanah, Bruce K Christensen, Eyal M ReingoldAbstract:Abstract The current study investigated the size and flexible control of Visual Span among patients with schizophrenia during Visual search performance. Visual Span is the region of the Visual field from which one extracts information during a single eye fixation, and a larger Visual Span size is linked to more efficient search performance. Therefore, a reduced Visual Span may explain patients’ impaired performance on search tasks. The gaze-contingent moving window paradigm was used to estimate the Visual Span size of patients and healthy participants while they performed two different search tasks. In addition, changes in Visual Span size were measured as a function of two manipulations of task difficulty: target–distractor similarity and stimulus familiarity. Patients with schizophrenia searched more slowly across both tasks and conditions. Patients also demonstrated smaller Visual Span sizes on the easier search condition in each task. Moreover, healthy controls’ Visual Span size increased as target discriminability or distractor familiarity increased. This modulation of Visual Span size, however, was reduced or not observed among patients. The implications of the present findings, with regard to previously reported Visual search deficits, and other functional and structural abnormalities associated with schizophrenia, are discussed.
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the Span of Visual processing in tactical displays
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2004Co-Authors: Jocelyn Keillor, Ipsa Desai, Justin G Hollands, Eyal M ReingoldAbstract:Visual Span, or the region of the Visual field from which information is extracted during a fixation, may vary as a function display complexity. As display technology evolves, military tactical displays show increasing quantities of information, often across large areas. To quantify the breadth with which an operator may process information presented in a tactical display, we related search performance to the amount of the display processed without an eye movement. The derived Visual Span measure was used to test the possibility that task requirements have an impact on the spatial extent of ”at a glance” processing. We compared Visual Span on searches based on threat affiliation (color) to those based on a combination of threat affiliation and heading (color and orientation) for two naval tactical symbol sets. We found that the task an operator engaged in while searching a complex tactical display affected the portion of the display that was processed ”at a glance”.
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Visual Span in expert chess players evidence from eye movements
Psychological Science, 2001Co-Authors: Eyal M Reingold, Neil Charness, Marc Pomplun, Dave M StampeAbstract:The reported research extends classic findings that after briefly viewing structured, but not random, chess positions, chess masters reproduce these positions much more accurately than less- skilled players. Using a combination of the gaze-contingent window paradigm and thechange blindness flicker paradigm, we documented dramatically larger Visual Spans for experts while processing struc- tured, but not random, chess positions. In addition, in a check- detection task, a minimized 3 ◊ 3 chessboard containing a King and potentially checking pieces was displayed. In this task, experts made fewer fixations per trial than less-skilled players, and had a greater proportion of fixations between individual pieces, rather than on pieces. Our results provide strong evidence for a perceptual encoding advantage for experts attributable to chess experience, rather than to a general perceptual or memory superiority. Simon and Chase (1973) proposed that much as Drosophila can be used as a model organism for the study of genetics, chess offers cognitive scientists an ideal task environment for the study of skilled performance. Since 1946, when de Groot (1978) conducted his pio- neering investigation showing that perception and memory are more important differentiators of expertise than is the ability to think ahead in the search for good moves, chess research has been instrumental in enhancing understanding of human expertise (Ericsson & Charness, 1994) and in contributing to the study of artificial intelligence (Char- ness, 1992). In a classic study, Chase and Simon (1973a, 1973b) replicated and extended de Groot's findings that after viewing chess positions for only a few seconds, chess masters were able to reproduce these positions much more accurately than less-skilled players. There was little difference in performance as a function of expertise when random board configurations were used, indicating that the superior immediate memory performance of the skilled players was not attrib- utable to a general superiority or unique structure of their memory systems or processes (e.g., photographic memory; see Binet, 1894). Rather, Chase and Simon postulated that experts use chess knowledge to create meaningful chunks consisting of several chess pieces, and are thus able to encode structured, but not random, chess configura- tions more quickly and accurately. More recently, a very small but reliable advantage in recall for random configurations has been shown for more expert players, though this is probably attributable to the occasional presence of familiar chunks in random positions (Gobet & Simon, 1996a). Further illustrating the critical importance of knowl- edge structures for performance, Chi's (1978) work comparing chil- dren who were skilled chess players with novice adults showed an advantage for children in chess recall, but an advantage for adults in digit recall. Chase and Simon (1973a, 1973b) hypothesized that much of the skilled chess player's advantage lies in the early perceptual organiza- tion and internal representation of the chess position. Specifically, they argued that the link between skilled perception and skilled prob- lem solving was to be found in the associations between perceptual chunks and generation of plausible moves. The size of an expert's vocabulary of chess-related configurations was initially estimated to be 50,000 to 100,000 chunks (Simon & Gilmartin, 1973), although small perceptual chunks are most likely supplemented by larger struc- tures termed templates (Gobet & Simon, 1996b).
