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Sylviane Valdois - One of the best experts on this subject based on the ideXlab platform.
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cross language modulation of visual attention span an arabic french spanish comparison in skilled adult readers
Frontiers in Psychology, 2016Co-Authors: Faris H R Awadh, Thierry Phenix, Alexia Antzaka, Marie Lallier, Manuel Carreiras, Sylviane ValdoisAbstract:In delineating the amount of orthographic information that can be processed in parallel during a single fixation, the visual attention (VA) span acts as a key component of the reading system. Previous studies focused on the contribution of VA span to normal and pathological reading in monolingual and bilingual children from different European languages, without direct cross-language comparison. In the current paper, we explored modulations of VA span abilities in three languages –French, Spanish, and Arabic– that differ in transparency, reading direction and writing systems. The participants were skilled adult readers who were native speakers of French, Spanish or Arabic. They were administered tasks of global and partial Letter report, single Letter Identification and text reading. Their VA span abilities were assessed using tasks that require the processing of briefly presented five consonant strings (e.g., R S H F T). All five consonants had to be reported in global report but a single cued Letter in partial report. Results showed that VA span was reduced in Arabic readers as compared to French or Spanish readers who otherwise show a similar high performance in the two report tasks. The analysis of VA span response patterns in global report showed a left-right asymmetry in all three languages. A leftward Letter advantage was found in French and Spanish but a rightward advantage in Arabic. The response patterns were symmetric in partial report, regardless of the language. Last, a significant relationship was found between VA span abilities and reading speed but only for French. The overall findings suggest that the size of VA span, the shape of VA span response patterns and the VA Span-reading relationship are modulated by language-specific features.
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A visual processing but no phonological disorder in a child with mixed dyslexia.
Cortex, 2011Co-Authors: Sylviane Valdois, Christel Bidet-ildei, Delphine Lassus-sangosse, Caroline Reilhac, Marie-ange N'guyen-morel, Eric Guinet, Jean-pierre OrliaguetAbstract:The case study of Martial, a French 9-year-old boy, who exhibits severe mixed dyslexia and surface dysgraphia is reported. Despite very poor pseudo-word reading, Martial has preserved phonological processing skills as his good oral language, good phoneme awareness and good verbal short-term memory show. He exhibited a strong length effect when reading briefly presented words but no sign of mini-neglect. His Letter-string processing abilities were assessed through tasks of whole and partial report. In whole report, Martial could only name a few Letters from briefly displayed 5-consonant strings. He showed an initial-position advantage and a sharper than expected left-to-right gradient of performance. He performed better when asked to report a single cued Letter within the string but then showed an atypical right-side advantage. The same rightward attentional bias was observed in whole report when top-down control was prevented. Otherwise, Martial showed preserved single Letter Identification skills and good processing of 5-Letter strings when Letters were sequentially displayed one at a time. His poor Letter-string processing thus reflects a parallel visual processing disorder that is compatible with either a visual attention (VA) span or a visual short-term memory disorder. Martial was further engaged in a complex reaching movement task involving VA and simultaneous processing. He performed motor sequences not as a whole but as a succession of independent motor units, suggesting that his attention was not allocated in parallel to the two to-be-reached targets prior to movement execution. Against a more basic motor disorder however, he showed good performance in a task of cyclical pointing movements. The overall findings suggest that Martial suffers from a visual simultaneous processing disorder that disturbs Letter Identification in strings. Instead of being restricted to Letter-string processing, this VA disorder might extend to non-verbal task.
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developmental dyslexia the visual attention span deficit hypothesis
Cognition, 2007Co-Authors: Marie-line Bosse, Marie-josephe Tainturier, Sylviane ValdoisAbstract:The visual attention (VA) span is defined as the amount of distinct visual elements which can be processed in parallel in a multi-element array. Both recent empirical data and theoretical accounts suggest that a VA span deficit might contribute to developmental dyslexia, independently of a phonological disorder. In this study, this hypothesis was assessed in two large samples of French and British dyslexic children whose performance was compared to that of chronological-age matched control children. Results of the French study show that the VA span capacities account for a substantial amount of unique variance in reading, as do phonological skills. The British study replicates this finding and further reveals that the contribution of the VA span to reading performance remains even after controlling IQ, verbal fluency, vocabulary and single Letter Identification skills, in addition to phoneme awareness. In both studies, most dyslexic children exhibit a selective phonological or VA span disorder. Overall, these findings support a multi-factorial view of developmental dyslexia. In many cases, developmental reading disorders do not seem to be due to phonological disorders. We propose that a VA span deficit is a likely alternative underlying cognitive deficit in dyslexia.
Jose Sahel - One of the best experts on this subject based on the ideXlab platform.
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the argus ii epiretinal prosthesis system allows Letter and word reading and long term function in patients with profound vision loss
British Journal of Ophthalmology, 2013Co-Authors: Lyndon Da Cruz, Brian Coley, Francesco Merlini, Eugene Filley, Punita Christopher, Fred K Chen, Varalakshmi Wuyyuru, Jose SahelAbstract:Background Retinal prosthesis systems (RPS) are a novel treatment for profound vision loss in outer retinal dystrophies. Ideal prostheses would offer stable, long-term retinal stimulation and reproducible spatial resolution in a portable form appropriate for daily life. Methods We report a prospective, internally controlled, multicentre trial of the Argus II system. Twenty-eight subjects with light perception vision received a retinal implant. Controlled, closed-group, forced-choice Letter Identification, and, open-choice two-, three- and four-Letter word Identification tests were carried out. Results The mean±SD percentage correct Letter Identification for 21 subjects tested were: Letters L, T, E, J, F, H, I, U, 72.3±24.6% system on and 17.7±12.9% system off; Letters A, Z, Q, V, N, W, O, C, D, M, 55.0±27.4% system on and 11.8%±10.7% system off, and Letters K, R, G, X, B, Y, S, P, 51.7±28.9% system on and 15.3±7.4% system off. (p Conclusions Multiple blind subjects fitted with the Argus II system consistently identified Letters and words using the device, indicating reproducible spatial resolution. This, in combination with stable, long-term function, represents significant progress in the evolution of artificial sight.
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the argus ii epiretinal prosthesis system allows Letter and word reading and long term function in patients with profound vision loss
British Journal of Ophthalmology, 2013Co-Authors: Lyndon Da Cruz, Brian Coley, Francesco Merlini, Eugene Filley, Punita Christopher, Fred K Chen, Varalakshmi Wuyyuru, Jose SahelAbstract:Background Retinal prosthesis systems (RPS) are a novel treatment for profound vision loss in outer retinal dystrophies. Ideal prostheses would offer stable, longterm retinal stimulation and reproducible spatial resolution in a portable form appropriate for daily life. Methods We report a prospective, internally controlled, multicentre trial of the Argus II system. Twenty-eight subjects with light perception vision received a retinal implant. Controlled, closed-group, forced-choice Letter Identification, and, open-choice two-, three- and fourLetter word Identification tests were carried out. Results The mean±SD percentage correct Letter Identification for 21 subjects tested were: Letters L, T, E, J, F, H, I, U, 72.3±24.6% system on and 17.7±12.9% system off; Letters A, Z, Q, V, N, W, O, C, D, M, 55.0 ±27.4% system on and 11.8%±10.7% system off, and Letters K, R, G, X, B, Y, S, P, 51.7±28.9% system on and 15.3±7.4% system off. (p<0.001 for all groups). A subgroup of six subjects was able to consistently read Letters of reduced size, the smallest measuring 0.9 cm (1.7°) at 30 cm, and four subjects correctly identify unrehearsed two-, three- and four-Letter words. Average implant duration was 19.9 months. Conclusions Multiple blind subjects fitted with the Argus II system consistently identified Letters and words using the device, indicating reproducible spatial resolution. This, in combination with stable, long-term function, represents significant progress in the evolution of artificial sight.
Fred K Chen - One of the best experts on this subject based on the ideXlab platform.
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the argus ii epiretinal prosthesis system allows Letter and word reading and long term function in patients with profound vision loss
British Journal of Ophthalmology, 2013Co-Authors: Lyndon Da Cruz, Brian Coley, Francesco Merlini, Eugene Filley, Punita Christopher, Fred K Chen, Varalakshmi Wuyyuru, Jose SahelAbstract:Background Retinal prosthesis systems (RPS) are a novel treatment for profound vision loss in outer retinal dystrophies. Ideal prostheses would offer stable, long-term retinal stimulation and reproducible spatial resolution in a portable form appropriate for daily life. Methods We report a prospective, internally controlled, multicentre trial of the Argus II system. Twenty-eight subjects with light perception vision received a retinal implant. Controlled, closed-group, forced-choice Letter Identification, and, open-choice two-, three- and four-Letter word Identification tests were carried out. Results The mean±SD percentage correct Letter Identification for 21 subjects tested were: Letters L, T, E, J, F, H, I, U, 72.3±24.6% system on and 17.7±12.9% system off; Letters A, Z, Q, V, N, W, O, C, D, M, 55.0±27.4% system on and 11.8%±10.7% system off, and Letters K, R, G, X, B, Y, S, P, 51.7±28.9% system on and 15.3±7.4% system off. (p Conclusions Multiple blind subjects fitted with the Argus II system consistently identified Letters and words using the device, indicating reproducible spatial resolution. This, in combination with stable, long-term function, represents significant progress in the evolution of artificial sight.
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the argus ii epiretinal prosthesis system allows Letter and word reading and long term function in patients with profound vision loss
British Journal of Ophthalmology, 2013Co-Authors: Lyndon Da Cruz, Brian Coley, Francesco Merlini, Eugene Filley, Punita Christopher, Fred K Chen, Varalakshmi Wuyyuru, Jose SahelAbstract:Background Retinal prosthesis systems (RPS) are a novel treatment for profound vision loss in outer retinal dystrophies. Ideal prostheses would offer stable, longterm retinal stimulation and reproducible spatial resolution in a portable form appropriate for daily life. Methods We report a prospective, internally controlled, multicentre trial of the Argus II system. Twenty-eight subjects with light perception vision received a retinal implant. Controlled, closed-group, forced-choice Letter Identification, and, open-choice two-, three- and fourLetter word Identification tests were carried out. Results The mean±SD percentage correct Letter Identification for 21 subjects tested were: Letters L, T, E, J, F, H, I, U, 72.3±24.6% system on and 17.7±12.9% system off; Letters A, Z, Q, V, N, W, O, C, D, M, 55.0 ±27.4% system on and 11.8%±10.7% system off, and Letters K, R, G, X, B, Y, S, P, 51.7±28.9% system on and 15.3±7.4% system off. (p<0.001 for all groups). A subgroup of six subjects was able to consistently read Letters of reduced size, the smallest measuring 0.9 cm (1.7°) at 30 cm, and four subjects correctly identify unrehearsed two-, three- and four-Letter words. Average implant duration was 19.9 months. Conclusions Multiple blind subjects fitted with the Argus II system consistently identified Letters and words using the device, indicating reproducible spatial resolution. This, in combination with stable, long-term function, represents significant progress in the evolution of artificial sight.
Faris H R Awadh - One of the best experts on this subject based on the ideXlab platform.
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cross language modulation of visual attention span an arabic french spanish comparison in skilled adult readers
Frontiers in Psychology, 2016Co-Authors: Faris H R Awadh, Thierry Phenix, Alexia Antzaka, Marie Lallier, Manuel Carreiras, Sylviane ValdoisAbstract:In delineating the amount of orthographic information that can be processed in parallel during a single fixation, the visual attention (VA) span acts as a key component of the reading system. Previous studies focused on the contribution of VA span to normal and pathological reading in monolingual and bilingual children from different European languages, without direct cross-language comparison. In the current paper, we explored modulations of VA span abilities in three languages –French, Spanish, and Arabic– that differ in transparency, reading direction and writing systems. The participants were skilled adult readers who were native speakers of French, Spanish or Arabic. They were administered tasks of global and partial Letter report, single Letter Identification and text reading. Their VA span abilities were assessed using tasks that require the processing of briefly presented five consonant strings (e.g., R S H F T). All five consonants had to be reported in global report but a single cued Letter in partial report. Results showed that VA span was reduced in Arabic readers as compared to French or Spanish readers who otherwise show a similar high performance in the two report tasks. The analysis of VA span response patterns in global report showed a left-right asymmetry in all three languages. A leftward Letter advantage was found in French and Spanish but a rightward advantage in Arabic. The response patterns were symmetric in partial report, regardless of the language. Last, a significant relationship was found between VA span abilities and reading speed but only for French. The overall findings suggest that the size of VA span, the shape of VA span response patterns and the VA Span-reading relationship are modulated by language-specific features.
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Cross-language modulation of visual attention span: An Arabic-French-Spanish comparison in adult skilled readers.
Frontiers Media S.A., 2016Co-Authors: Faris H R Awadh, Thierry Ephénix, Alexia Eantzaka, Marie Elallier, Manuel Ecarreiras, Sylviane EvaldoisAbstract:In delineating the amount of orthographic information that can be processed in parallel during a single fixation, the visual attention (VA) span acts as a key component of the reading system. Previous studies focused on the contribution of VA span to normal and pathological reading in monolingual and bilingual children from different European languages, without direct cross-language comparison. In the current paper, we explored modulations of VA span abilities in three languages --French, Spanish and Arabic-- that differ in transparency, reading direction and writing systems. The participants were adult skilled readers who were native speakers of French, Spanish or Arabic. They were administered tasks of global and partial Letter report, single Letter Identification and text reading. Their VA span abilities were assessed using tasks that require the processing of briefly presented 5 consonant strings (e.g., R S H F T). All five consonants had to be reported in global report but a single cued Letter in partial report. Results showed that the VA span was reduced in Arabic readers as compared to French or Spanish readers who otherwise show a similar high performance in the two report tasks. The analysis of VA span response patterns in global report showed a left-right asymmetry in all three languages. A leftward Letter advantage was found in French and Spanish but a rightward advantage in Arabic. The response patterns were symmetric in partial report, regardless of the language. Last, a significant relationship was found between visual attention span abilities and reading speed but only for French. The overall findings suggest that the size of VA span, the shape of VA span response patterns and the VA Span-reading relationship are modulated by language-specific features
Melanie Palomares - One of the best experts on this subject based on the ideXlab platform.
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grouping in object recognition the role of a gestalt law in Letter Identification
Cognitive Neuropsychology, 2009Co-Authors: Denis G Pelli, Najib J Majaj, Noah Raizman, Christopher Christian, Melanie PalomaresAbstract:The Gestalt psychologists reported a set of laws describing how vision groups elements to recognize objects. The Gestalt laws “prescribe for us what we are to recognize ‘as one thing’” (Kohler, 1920). Were they right? Does object recognition involve grouping? Tests of the laws of grouping have been favourable, but mostly assessed only detection, not Identification, of the compound object. The grouping of elements seen in the detection experiments with lattices and “snakes in the grass” is compelling, but falls far short of the vivid everyday experience of recognizing a familiar, meaningful, named thing, which mediates the ordinary Identification of an object. Thus, after nearly a century, there is hardly any evidence that grouping plays a role in ordinary object recognition. To assess grouping in object recognition, we made Letters out of grating patches and measured threshold contrast for identifying these Letters in visual noise as a function of perturbation of grating orientation, phase, and offset. We...
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The Role of Spatial Frequency Channels in Letter Identification
2007Co-Authors: Najib J Majaj, Denis G Pelli, Peri Kurshan, Melanie PalomaresAbstract:How we see is today explained by physical optics and retinal transduction, followed by feature detection, in the cortex, by a bank of parallel independent spatial-frequency-selective channels. It is assumed that the observer uses whichever channels are best for the task at hand. Our current results demand a revision of this framework: Observers are not free to choose which channels they use. We used critical-band masking to characterize the channels mediating Identification of broadband signals: Letters in a wide range of fonts (Sloan, Bookman, Knstler, Yung), alphabets (Roman and Chinese), and sizes (0.1 to 55 deg). We also tested sinewave and squarewave gratings. Masking always revealed a single channel, 1.60.7 octaves wide, with a center frequency that depends on Letter size and alphabet. We define an alphabet's stroke frequency as the average number of lines crossed by a slice through a Letter, divided by the Letter width. For sharp-edged (i.e. broadband) signals, we find that stroke frequency completely determines channel frequency, independent of alphabet, font, and size. Moreover, even though observers have multiple channels, they always use the same channel for the same signals, even after hundreds of trials, regardless of whether the noise is low-pass, high-pass, or all-pass. This shows that observers identify Letters through a single channel that is selected bottom-up, by the signal, not top-down by the observer. We thought shape would be processed similarly at all sizes. Bandlimited signals conform more to this expectation than do broadband signals. Here, we characterize processing by channel frequency. For sinewave gratings, as expected, channel frequency equals sinewave frequency ff channel = . For bandpass-filtered Letters, channel frequency is proportiona..
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the role of spatial frequency channels in Letter Identification
Vision Research, 2002Co-Authors: Najib J Majaj, Denis G Pelli, Peri Kurshan, Melanie PalomaresAbstract:Abstract How we see is today explained by physical optics and retinal transduction, followed by feature detection, in the cortex, by a bank of parallel independent spatial-frequency-selective channels. It is assumed that the observer uses whichever channels are best for the task at hand. Our current results demand a revision of this framework: Observers are not free to choose which channels they use. We used critical-band masking to characterize the channels mediating Identification of broadband signals: Letters in a wide range of fonts (Sloan, Bookman, Kunstler, Yung), alphabets (Roman and Chinese), and sizes (0.1–55°). We also tested sinewave and squarewave gratings. Masking always revealed a single channel, 1.6±0.7 octaves wide, with a center frequency that depends on Letter size and alphabet. We define an alphabet's stroke frequency as the average number of lines crossed by a slice through a Letter, divided by the Letter width. For sharp-edged (i.e. broadband) signals, we find that stroke frequency completely determines channel frequency, independent of alphabet, font, and size. Moreover, even though observers have multiple channels, they always use the same channel for the same signals, even after hundreds of trials, regardless of whether the noise is low-pass, high-pass, or all-pass. This shows that observers identify Letters through a single channel that is selected bottom-up, by the signal, not top-down by the observer. We thought shape would be processed similarly at all sizes. Bandlimited signals conform more to this expectation than do broadband signals. Here, we characterize processing by channel frequency. For sinewave gratings, as expected, channel frequency equals sinewave frequency fchannel=f. For bandpass-filtered Letters, channel frequency is proportional to center frequency fchannel∝fcenter (log–log slope 1) when size is varied and the band (c/Letter) is fixed, but channel frequency is less than proportional to center frequency fchannel∝fcenter2/3 (log–log slope 2/3) when the band is varied and size is fixed. Finally, our main result, for sharp-edged (i.e. broadband) Letters and squarewaves, channel frequency depends solely on stroke frequency, f channel /10 c/deg = f stroke /10 c/deg 2/3 , with a log–log slope of 2/3. Thus, large Letters (and coarse squarewaves) are identified by their edges; small Letters (and fine squarewaves) are identified by their gross strokes.
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The Role of Spatial Frequency Channels in Letter Identification
2002Co-Authors: Najib J Majaj, Denis G Pelli, Peri Kurshan, Melanie PalomaresAbstract:How we see is today explained by physical optics and retinal transduction, followed by feature detection, in the cortex, by a bank of parallel independent spatial-frequency-selective channels. It is assumed that the observer uses whichever channels are best for the task at hand. Our current results demand a revision of this framework: Observers are not free to choose which channels they use. We used critical-band masking to characterize the channels mediating Identification of broadband signals: Letters in a wide range of fonts (Sloan, Bookman, Knstler, Yung), alphabets (Roman and Chinese), and sizes (0.1 to 55 deg). We also tested sinewave and squarewave gratings. Masking always revealed a single channel, 1.60.7 octaves wide, with a center frequency that depends on Letter size and alphabet. We define an alphabet's stroke frequency as the average number of lines crossed by a slice through a Letter, divided by the Letter width. For sharp-edged (i.e. broadband) signals, we find that stroke frequency completely determines channel frequency, independent of alphabet, font, and size. Moreover, even though observers have multiple channels, they always use the same channel for the same signals, even after hundreds of trials, regardless of whether the noise is low-pass, high-pass, or all-pass. This shows that observers identify Letters through a single channel that is selected bottom-up, by the signal, not top-down by the observer. We thought shape would be processed similarly at all sizes. Bandlimited signals conform more to this expectation than do broadband signals. Here, we characterize processing by channel frequency. For sinewave gratings, as expected, channel frequency equals sinewave frequency ff channel = . For "Channels for Letters." Draft 35. Resubmitted to Vision R..
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The role of spatial frequency channels in Letter Identification
2002Co-Authors: Najib J Majaj, Denis G Pelli, Peri Kurshan, Melanie PalomaresAbstract:How we see is today explained by physical optics and retinal transduction, followed by feature detection, in the cortex, by a bank of parallel independent spatial-frequency-selective channels. It is assumed that the observer uses whichever channels are best for the task at hand. Our current results demand a revision of this framework: Observers are not free to choose which channels they use. We used critical-band masking to characterize the channels mediating Identification of broadband signals: Letters in a wide range of fonts (Sloan, Bookman, K€unstler, Yung), alphabets (Roman and Chinese), and sizes (0.1–55). We also tested sinewave and squarewave gratings. Masking always revealed a single channel, 1:6 0:7 octaves wide, with a center frequency that depends on Letter size and alphabet. We define an alphabet’s stroke frequency as the average number of lines crossed by a slice through a Letter, divided by the Letter width. For sharp-edged (i.e. broadband) signals, we find that stroke frequency completely determines channel frequency, independent of alphabet, font, and size. Moreover, even though observers have multiple channels, they always use the same channel for the same signals, even after hundreds of trials, regardless of whether the noise is low-pass, high-pass, or all-pass. This shows that observers identify Letters through a single channel that is selected bottom-up, by the signal, not top-down by the observer. We thought shape would be processed similarly at all sizes. Bandlimited signals conform more to this expectation than do broadband signals. Here, we characterize processing by channel frequency. For sinewave gratings, as expected, channel frequency equals sinewave frequency fchannel f. For bandpass-filtered Letters, channel frequency is proportional to center frequenc
