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Provazza S, Carretti B, Giofrè D, Adams AM, Montesano L, Roberts D. Shallow or deep? The impact of orthographic depth on visual processing impairments in developmental dyslexia. ANNALS OF DYSLEXIA 2022; 72:171-196. [PMID: 35286579 PMCID: PMC8942915 DOI: 10.1007/s11881-021-00249-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 11/28/2021] [Indexed: 06/14/2023]
Abstract
The extent to which impaired visual and phonological mechanisms may contribute to the manifestation of developmental dyslexia across orthographies of varying depth has yet to be fully established. By adopting a cross-linguistic approach, the current study aimed to explore the nature of visual and phonological processing in developmental dyslexic readers of shallow (Italian) and deep (English) orthographies, and specifically the characterisation of visual processing deficits in relation to orthographic depth. To achieve this aim, we administered a battery of non-reading visual and phonological tasks. Developmental dyslexics performed worse than typically developing readers on all visual and phonological tasks. Critically, readers of the shallow orthography were disproportionately impaired on visual processing tasks. Our results suggest that the impaired reading and associated deficits observed in developmental dyslexia are anchored by dual impairments to visual and phonological mechanisms that underpin reading, with the magnitude of the visual deficit varying according to orthographic depth.
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Affiliation(s)
- Serena Provazza
- School of Psychology, Liverpool John Moores University, Liverpool, UK
| | - Barbara Carretti
- Department of General Psychology, University of Padova, Padua, Italy
| | - David Giofrè
- School of Psychology, Liverpool John Moores University, Liverpool, UK
- Department of Educational Sciences, University of Genoa, Genoa, Italy
| | - Anne-Marie Adams
- School of Psychology, Liverpool John Moores University, Liverpool, UK
| | | | - Daniel Roberts
- Centre for Cognitive Neuroscience, Division of Psychology, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK.
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2
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Cohen L. Acquired dyslexias following temporal lesions. HANDBOOK OF CLINICAL NEUROLOGY 2022; 187:277-285. [PMID: 35964977 DOI: 10.1016/b978-0-12-823493-8.00003-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The acquisition of reading by children is supported by deep changes in the brain systems devoted to vision and language. The left temporal lobe contributes critically to both systems, and lesions affecting it may therefore cause both peripheral vision-related and central language-related reading impairments. The diversity of peripheral dyslexias reflects the anatomical and functional division of the visual cortex into early visual regions, whose lesions have a limited impact on reading; ventral regions, whose lesions are mostly associated to Pure Alexia; and dorsal regions, whose lesions may yield spatial, neglect-related, and attentional dyslexias. Similarly, central alexias reflect the broad distinction, within language processes, between phonological and lexico-semantic components. Phonological and surface dyslexias roughly result from impairment of the former and the latter processes, respectively, while deep dyslexia may be seen as the association of both. In this chapter, we review such types of acquired dyslexias, their clinical features, pathophysiology, and anatomical correlates.
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Affiliation(s)
- Laurent Cohen
- Paris Brain Institute, Hôpital de la Pitié-Salpêtrière, Paris, France.
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3
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Bonandrini R, Veronelli L, Licciardo D, Caporali A, Judica E, Corbo M, Luzzatti C. Can the right hemisphere read? A behavioral and disconnectome study on implicit reading in a patient with pure alexia. Neurocase 2020; 26:321-327. [PMID: 33026948 DOI: 10.1080/13554794.2020.1830118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Patients with pure alexia have major difficulties in reading aloud. However, they often perform above chance level in reading tasks that do not require overt articulation of the target word - like lexical decision or semantic judgment - a phenomenon usually known as "implicit reading." There is no agreement in the literature on whether implicit reading should be attributed to relative sparing of some left hemisphere (LH) reading centers or rather to signs of compensatory endeavors by the right hemisphere (RH). We report the case of an 81-year-old patient (AA) with pure alexia due to a lesion involving the left occipital lobe and the temporal infero-mesial areas, as well as the posterior callosal pathways. Although AA's reading was severely impaired and proceeded letter by letter, she showed an above-chance-level performance for frequent concrete words in a tachistoscopic lexical decision task. A structural disconnectome analysis revealed that AA's lesion not only affected the left occipital cortex and the splenium: it also disconnected white-matter tracts meant to connect the visual word-form system to decision-related frontal areas within the LH. We suggest that the RH, rather than the LH, may be responsible for patient AA's implicit reading.
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Affiliation(s)
- Rolando Bonandrini
- Department of Psychology, University of Milan-Bicocca , Milan, Italy.,Milan Center for Neuroscience , Milan, Italy
| | - Laura Veronelli
- Department of Neurorehabilitation Sciences, Casa di Cura del Policlinico , Milan, Italy
| | - Daniele Licciardo
- Department of Psychology, University of Milan-Bicocca , Milan, Italy.,Milan Center for Neuroscience , Milan, Italy.,School of Medicine and Surgery, University of Milan-Bicocca , Monza, Italy
| | - Alessandra Caporali
- Department of Neurorehabilitation Sciences, Casa di Cura del Policlinico , Milan, Italy
| | - Elda Judica
- Department of Neurorehabilitation Sciences, Casa di Cura del Policlinico , Milan, Italy
| | - Massimo Corbo
- Department of Neurorehabilitation Sciences, Casa di Cura del Policlinico , Milan, Italy
| | - Claudio Luzzatti
- Department of Psychology, University of Milan-Bicocca , Milan, Italy.,Milan Center for Neuroscience , Milan, Italy
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Provazza S, Adams AM, Giofrè D, Roberts DJ. Double Trouble: Visual and Phonological Impairments in English Dyslexic Readers. Front Psychol 2020; 10:2725. [PMID: 31920790 PMCID: PMC6927912 DOI: 10.3389/fpsyg.2019.02725] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 11/18/2019] [Indexed: 11/13/2022] Open
Abstract
Developmental dyslexia is a reading disorder characterized by problems in accurate or fluent reading. A deficiency in phonological processing is thought to underpin the reading difficulties of individuals with developmental dyslexia and a variety of explanations have been proposed including deficits in phonological awareness and verbal memory. Recent investigations have begun to suggest that developmental deficits in the acquisition of reading may also co-occur with visual processing deficits, which are particularly salient for visually complex stimuli, yet these deficits have received relatively little attention from researchers. To further explore the nature of phonological and visual processing in developmental dyslexia, we administered a series of non-reading tasks tapping both domains. Unsurprisingly, individuals with developmental dyslexia performed worse than typically developing readers in phonological tasks. More intriguingly, they also struggled with visual tasks, specifically when discriminating between novel visual patterns, and in visuo-spatial working memory, which requires greater attentional control. These findings highlight that individuals with developmental dyslexia present not only with phonological impairments but also difficulties in processing visual materials. This aspect has received limited attention in previous literature and represents an aspect of novelty of this study. The dual phonological and visual impairments suggest that developmental dyslexia is a complex disorder characterized by deficits in different cognitive mechanisms that underpin reading.
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Affiliation(s)
- Serena Provazza
- Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Anne-Marie Adams
- Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - David Giofrè
- Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom.,Department of Educational Sciences, University of Genoa, Genoa, Italy
| | - Daniel John Roberts
- Division of Psychology, Centre for Cognitive Neuroscience, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
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Provazza S, Giofrè D, Adams AM, Roberts DJ. The Clock Counts - Length Effects in English Dyslexic Readers. Front Psychol 2019; 10:2495. [PMID: 31780998 PMCID: PMC6861451 DOI: 10.3389/fpsyg.2019.02495] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/22/2019] [Indexed: 12/02/2022] Open
Abstract
In reading, length effects (LEs) are defined as an increment in the time taken to read as a function of word length and may indicate whether reading is proceeding in an efficient whole word fashion or by serial letter processing. LEs are generally considered to be a pathognomonic symptom of developmental dyslexia (DD) and predominantly have been investigated in transparent orthographies where reading impairment is characterized as slow and effortful. In the present study a sample of 18 adult participants with DD were compared to a matched sample of typical developing readers to investigate whether the LE is a critical aspect of DD in an opaque orthography, English. We expected that the DD group would present with marked LEs, in both words and non-words, compared to typical developing readers. The presence of LEs in the DD group confirmed our prediction. These effects were particularly strong in low frequency words and in non-words, as observed in reading speed. These preliminary findings may have important theoretical implications for current understanding of DD.
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Affiliation(s)
- S. Provazza
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - D. Giofrè
- Department of Education Sciences, School of Social Sciences, University of Genoa, Genoa, Italy
| | - A.-M. Adams
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - D. J. Roberts
- Division of Psychology, Centre for Cognitive Neuroscience, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
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Abstract
Reading causes widespread changes in the brain, but its effect on visual word representations is unknown. Learning to read may facilitate visual processing by forming specialized detectors for longer strings or by making word responses more predictable from single letters—that is, by increasing compositionality. We provided evidence for the latter hypothesis using experiments that compared nonoverlapping groups of readers of two Indian languages (Telugu and Malayalam). Readers showed increased single-letter discrimination and decreased letter interactions for bigrams during visual search. Importantly, these interactions predicted subjects’ overall reading fluency. In a separate brain-imaging experiment, we observed increased compositionality in readers, whereby responses to bigrams were more predictable from single letters. This effect was specific to the anterior lateral occipital region, where activations best matched behavior. Thus, learning to read facilitates visual processing by increasing the compositionality of visual word representations.
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Affiliation(s)
- Aakash Agrawal
- Centre for BioSystems Science and Engineering, Indian Institute of Science
| | - K V S Hari
- Department of Electrical Communication Engineering, Indian Institute of Science
| | - S P Arun
- Centre for Neuroscience, Indian Institute of Science
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7
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Mapping the intersection of language and reading: the neural bases of the primary systems hypothesis. Brain Struct Funct 2018; 223:3769-3786. [PMID: 30073420 DOI: 10.1007/s00429-018-1716-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/10/2018] [Indexed: 10/28/2022]
Abstract
The primary systems framework has been used to relate behavioural performance across many different language activities to the status of core underpinning domain-general cognitive systems. This study provided the first quantitative investigation of this account at both behavioural and neural levels in a group of patients with chronic post-stroke aphasia. Principal components analysis was used to distil orthogonal measures of phonological and semantic processing, which were then related to reading performance and the underlying lesion distributions using voxel-based correlational methodology. Concrete word reading involved both a ventral semantic pathway, and inferior and anterior aspects of the dorsal phonological pathway. Abstract word reading overlapped with the ventral semantic pathway but also drew more extensively on the superior and posterior aspects of the dorsal phonological pathway. Nonword reading was related to phonological processing along the dorsal pathway and was also supported by a more superior set of regions previously associated with speech motor output. The use of continuous measures of behavioural performance and neural integrity allowed us to elucidate for the first time both the lesion and behavioural correlates for the semantic and phonological components of the primary systems hypothesis and to extend these by identifying the importance of an additional dorsal speech motor output system. These results provide a target for future neuroanatomically constrained computational models of reading.
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Silkes JP. Masked Repetition Priming Treatment for Anomia. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2018; 61:690-712. [PMID: 29486491 PMCID: PMC6195064 DOI: 10.1044/2017_jslhr-l-17-0192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 10/03/2017] [Accepted: 11/25/2017] [Indexed: 06/08/2023]
Abstract
PURPOSE Masked priming has been suggested as a way to directly target implicit lexical retrieval processes in aphasia. This study was designed to investigate repeated use of masked repetition priming to improve picture naming in individuals with anomia due to aphasia. METHOD A single-subject, multiple-baseline design was used across 6 people with aphasia. Training involved repeated exposure to pictures that were paired with masked identity primes or sham primes. Two semantic categories were trained in series for each participant. Analyses assessed treatment effects, generalization within and across semantic categories, and effects on broader language skills, immediately and 3 months after treatment. RESULTS Four of the 6 participants improved in naming trained items immediately after treatment. Improvements were generally greater for items that were presented in training with masked identity primes than items that were presented repeatedly during training with masked sham primes. Generalization within and across semantic categories was limited. Generalization to broader language skills was inconsistent. CONCLUSION Masked repetition priming may improve naming for some individuals with anomia due to aphasia. A number of methodological and theoretical insights into further development of this treatment approach are discussed.
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Affiliation(s)
- JoAnn P. Silkes
- Department of Speech and Hearing Sciences, University of Washington, Seattle
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Woollams AM, Lambon Ralph MA, Madrid G, Patterson KE. Do You Read How I Read? Systematic Individual Differences in Semantic Reliance amongst Normal Readers. Front Psychol 2016; 7:1757. [PMID: 27920731 PMCID: PMC5118465 DOI: 10.3389/fpsyg.2016.01757] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 10/25/2016] [Indexed: 11/25/2022] Open
Abstract
The extent to which meaning is involved in reading aloud has proven an area of longstanding debate, and current computational models differ on this dimension. The connectionist triangle model proposes that normal individuals rely on semantic information for correct reading of words with atypical spelling-sound relationships, but to varying degrees. This proposed individual difference would account for the varying stage of decline at which patients with semantic dementia first show the reading impairment known as surface dyslexia. Recent neuroimaging data has provided validation of this view, showing that individual differences in degree of semantic reliance during exception word reading predict the amount of activation in left anterior temporal regions associated with semantic processing. This study aimed to establish the cognitive correlates of individual differences in semantic reliance during exception word reading. Experiment 1 used a subgrouping approach with 32 participants and found larger imageability and semantic priming effects specifically for exception word reading amongst high relative to low semantic reliance readers. High semantic reliance readers also tended to read nonwords more slowly than low semantic reliance readers. A second experiment used a regression approach with 129 readers and confirmed the relationship of degree of semantic reliance both to imageability effects in exception word reading and speed of nonword reading. Further, while the performance of the higher semantic readers revealed no significant association with semantic processing tasks, there was a negative relationship with rhyme processing tasks. We therefore speculate that differences in phonological abilities may be responsible for varying degrees of semantic reliance in reading aloud. This proposal accords with the results of functional imaging showing that higher semantic reliance during exception word reading corresponds to lower activation in left pre-central gyrus, an area associated with direct spelling sound mapping and phonological processing. Our results therefore establish the nature of systematic individual differences in degree of semantic involvement amongst normal readers, and suggest directions for future neuroimaging and computational modeling research to uncover their origins.
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Affiliation(s)
- Anna M Woollams
- Neuroscience and Aphasia Research Unit, University of ManchesterManchester, UK; MRC Cognition and Brain Sciences UnitCambridge, UK
| | | | - Gaston Madrid
- Neuroscience and Aphasia Research Unit, University of Manchester Manchester, UK
| | - Karalyn E Patterson
- MRC Cognition and Brain Sciences UnitCambridge, UK; Department of Clinical Neurosciences, University of CambridgeCambridge, UK
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10
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Johnson RL, Raphail AM. Untangling letter confusability and word length effects in pure alexia. Cogn Neuropsychol 2016; 32:442-56. [DOI: 10.1080/02643294.2015.1113945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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11
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Roberts DJ, Lambon Ralph MA, Kim E, Tainturier MJ, Beeson PM, Rapcsak SZ, Woollams AM. Processing deficits for familiar and novel faces in patients with left posterior fusiform lesions. Cortex 2015; 72:79-96. [PMID: 25837867 PMCID: PMC4643682 DOI: 10.1016/j.cortex.2015.02.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 01/30/2015] [Accepted: 02/03/2015] [Indexed: 11/25/2022]
Abstract
Pure alexia (PA) arises from damage to the left posterior fusiform gyrus (pFG) and the striking reading disorder that defines this condition has meant that such patients are often cited as evidence for the specialisation of this region to processing of written words. There is, however, an alternative view that suggests this region is devoted to processing of high acuity foveal input, which is particularly salient for complex visual stimuli like letter strings. Previous reports have highlighted disrupted processing of non-linguistic visual stimuli after damage to the left pFG, both for familiar and unfamiliar objects and also for novel faces. This study explored the nature of face processing deficits in patients with left pFG damage. Identification of famous faces was found to be compromised in both expressive and receptive tasks. Discrimination of novel faces was also impaired, particularly for those that varied in terms of second-order spacing information, and this deficit was most apparent for the patients with the more severe reading deficits. Interestingly, discrimination of faces that varied in terms of feature identity was considerably better in these patients and it was performance in this condition that was related to the size of the length effects shown in reading. This finding complements functional imaging studies showing left pFG activation for faces varying only in spacing and frontal activation for faces varying only on features. These results suggest that the sequential part-based processing strategy that promotes the length effect in the reading of these patients also allows them to discriminate between faces on the basis of feature identity, but processing of second-order configural information is most compromised due to their left pFG lesion. This study supports a view in which the left pFG is specialised for processing of high acuity foveal visual information that supports processing of both words and faces.
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Affiliation(s)
- Daniel J Roberts
- Research Centre in Brain and Behaviour, Liverpool John Moores University, UK
| | - Matthew A Lambon Ralph
- Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester, UK
| | - Esther Kim
- Department of Speech Pathology and Audiology, University of Alberta, Canada
| | | | - Pelagie M Beeson
- Department of Speech, Language, and Hearing Sciences, University of Arizona, USA
| | - Steven Z Rapcsak
- Department of Neurology, University of Arizona, USA; Neurology Section, Southern Arizona VA Health Care System, Tucson, AZ, USA
| | - Anna M Woollams
- Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester, UK.
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Silkes JP. Masked Repetition Priming in Treatment of Anomia: A Phase 2 Study. AMERICAN JOURNAL OF SPEECH-LANGUAGE PATHOLOGY 2015; 24:S895-S912. [PMID: 26381369 PMCID: PMC4698472 DOI: 10.1044/2015_ajslp-14-0138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 02/10/2015] [Accepted: 05/11/2015] [Indexed: 06/05/2023]
Abstract
PURPOSE Previous research has demonstrated that exposure to masked primes may improve naming accuracy for individuals with anomia. This study investigates the effect of repeated exposures to masked identity primes paired with pictures over multiple trials, sessions, and days on the ability of people with anomia to name those pictures. METHOD Four participants with anomia completed this single-subject, multiple-baseline design study. Twelve treatment sessions were conducted for each of 2 semantic categories. Comparisons of performance on naming probes were made between items that were primed, unprimed but seen the same number of times, and unprimed and seen only during naming probes. RESULTS All participants showed some gains in naming trained items although to varying degrees, and trained (primed) items generally showed greater improvement than untrained items seen the same number of times. Cross-category generalization was observed for some participants, but little to no within-category generalization occurred. Minimal changes occurred on measures of general language ability. CONCLUSIONS These data provide continued evidence that masked repetition priming can have a positive effect on naming for people with anomia. Factors that may influence participant response and additional questions that must be settled for this line of research to continue are discussed.
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Taylor JSH, Duff FJ, Woollams AM, Monaghan P, Ricketts J. How Word Meaning Influences Word Reading. CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 2015. [DOI: 10.1177/0963721415574980] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Understanding how we read is a fundamental question for psychology, with critical implications for education. Studies of word reading tend to focus on the mappings between the written and spoken forms of words. In this article, we review evidence from developmental, neuroimaging, neuropsychological, and computational studies that show that knowledge of word meanings is inextricably involved in word reading. Consequently, models of reading must better specify the role of meaning in skilled reading and its acquisition. Further, our review paves the way for educationally realistic research to confirm whether explicit teaching of oral vocabulary improves word reading.
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Affiliation(s)
- J. S. H. Taylor
- Department of Psychology, Royal Holloway, University of London
| | - Fiona J. Duff
- Department of Experimental Psychology, University of Oxford
| | | | | | - Jessie Ricketts
- Department of Psychology, Royal Holloway, University of London
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Woollams AM. Lexical is as lexical does: computational approaches to lexical representation. LANGUAGE, COGNITION AND NEUROSCIENCE 2015; 30:395-408. [PMID: 25893204 PMCID: PMC4396497 DOI: 10.1080/23273798.2015.1005637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In much of neuroimaging and neuropsychology, regions of the brain have been associated with 'lexical representation', with little consideration as to what this cognitive construct actually denotes. Within current computational models of word recognition, there are a number of different approaches to the representation of lexical knowledge. Structural lexical representations, found in original theories of word recognition, have been instantiated in modern localist models. However, such a representational scheme lacks neural plausibility in terms of economy and flexibility. Connectionist models have therefore adopted distributed representations of form and meaning. Semantic representations in connectionist models necessarily encode lexical knowledge. Yet when equipped with recurrent connections, connectionist models can also develop attractors for familiar forms that function as lexical representations. Current behavioural, neuropsychological and neuroimaging evidence shows a clear role for semantic information, but also suggests some modality- and task-specific lexical representations. A variety of connectionist architectures could implement these distributed functional representations, and further experimental and simulation work is required to discriminate between these alternatives. Future conceptualisations of lexical representations will therefore emerge from a synergy between modelling and neuroscience.
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Affiliation(s)
- Anna M. Woollams
- Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester, Zochonis Building, Brunswick Street, ManchesterM13 9PL, UK
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15
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Abstract
Pure alexia is a severe impairment of word reading in which individuals process letters serially with a pronounced length effect. Yet, there is considerable variation in the performance of alexic readers with generally very slow, but also occasionally fast responses, an observation addressed rarely in previous reports. It has been suggested that "fast" responses in pure alexia reflect residual parallel letter processing or that they may even be subserved by an independent reading system. Four experiments assessed fast and slow reading in a participant (DN) with pure alexia. Two behavioral experiments investigated frequency, neighborhood, and length effects in forced fast reading. Two further experiments measured eye movements when DN was forced to read quickly, or could respond faster because words were easier to process. Taken together, there was little support for the proposal that "qualitatively different" mechanisms or reading strategies underlie both types of responses in DN. Instead, fast responses are argued to be generated by the same serial-reading strategy.
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Affiliation(s)
- Tobias Bormann
- a Neurologische Universitätsklinik , Universitätsklinik Freiburg , Freiburg , Germany
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16
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Affiliation(s)
- Randi Starrfelt
- a Department of Psychology , University of Copenhagen , Copenhagen , Denmark
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17
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Abstract
The article is concerned with inferences from the behaviour of neurological patients to models of normal function. It takes the letter-by-letter reading strategy common in pure alexic patients as an example of the methodological problems involved in making such inferences that compensatory strategies produce. The evidence is discussed on the possible use of three ways the letter-by-letter reading process might operate: "reversed spelling"; the use of the phonological input buffer as a temporary holding store during word building; and the use of serial input to the visual word-form system entirely within the visual-orthographic domain such as in the model of Plaut [1999. A connectionist approach to word reading and acquired dyslexia: Extension to sequential processing. Cognitive Science, 23, 543-568]. The compensatory strategy used by, at least, one pure alexic patient does not fit with the third of these possibilities. On the more general question, it is argued that even if compensatory strategies are being used, the behaviour of neurological patients can be useful for the development and assessment of first-generation information-processing models of normal function, but they are not likely to be useful for the development and assessment of second-generation computational models.
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Affiliation(s)
- Tim Shallice
- a Institute of Cognitive Neuroscience , University College London , London , UK
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18
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Woollams AM, Hoffman P, Roberts DJ, Lambon Ralph MA, Patterson KE. What lies beneath: a comparison of reading aloud in pure alexia and semantic dementia. Cogn Neuropsychol 2014; 31:461-81. [PMID: 24702272 PMCID: PMC4131257 DOI: 10.1080/02643294.2014.882300] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Exaggerated effects of word length upon reading-aloud performance define pure alexia, but have also been observed in semantic dementia. Some researchers have proposed a reading-specific account, whereby performance in these two disorders reflects the same cause: impaired orthographic processing. In contrast, according to the primary systems view of acquired reading disorders, pure alexia results from a basic visual processing deficit, whereas degraded semantic knowledge undermines reading performance in semantic dementia. To explore the source of reading deficits in these two disorders, we compared the reading performance of 10 pure alexic and 10 semantic dementia patients, matched in terms of overall severity of reading deficit. The results revealed comparable frequency effects on reading accuracy, but weaker effects of regularity in pure alexia than in semantic dementia. Analysis of error types revealed a higher rate of letter-based errors and a lower rate of regularization responses in pure alexia than in semantic dementia. Error responses were most often words in pure alexia but most often nonwords in semantic dementia. Although all patients made some letter substitution errors, these were characterized by visual similarity in pure alexia and phonological similarity in semantic dementia. Overall, the data indicate that the reading deficits in pure alexia and semantic dementia arise from impairments of visual processing and knowledge of word meaning, respectively. The locus and mechanisms of these impairments are placed within the context of current connectionist models of reading.
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Affiliation(s)
- Anna M Woollams
- a School of Psychological Sciences , University of Manchester , Manchester , UK
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Abstract
Acquired reading problems caused by brain injury (alexia) are common, either as a part of an aphasic syndrome, or as an isolated symptom. In pure alexia, reading is impaired while other language functions, including writing, are spared. Being in many ways a simple syndrome, one would think that pure alexia was an easy target for rehabilitation efforts. We review the literature on rehabilitation of pure alexia from 1990 to the present, and find that patients differ widely on several dimensions, such as alexia severity and associated deficits. Many patients reported to have pure alexia in the reviewed studies, have associated deficits such as agraphia or aphasia and thus do not strictly conform to the diagnosis. Few studies report clear and generalisable effects of training, none report control data, and in many cases the reported findings are not supported by statistics. We can, however, tentatively conclude that Multiple Oral Re-reading techniques may have some effect in mild pure alexia where diminished reading speed is the main problem, while Tacile-Kinesthetic training may improve letter identification in more severe cases of alexia. There is, however, still a great need for well-designed and controlled studies of rehabilitation of pure alexia.
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Affiliation(s)
- Randi Starrfelt
- a Department of Psychology , University of Copenhagen , Denmark
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Ablinger I, Huber W, Schattka KI, Radach R. Recovery in a letter-by-letter reader: more efficiency at the expense of normal reading strategy. Neurocase 2013; 19:236-55. [PMID: 22519556 DOI: 10.1080/13554794.2012.667119] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Although changes in reading performance of recovering letter-by-letter readers have been described in some detail, no prior research has provided an in-depth analysis of the underlying adaptive word processing strategies. Our work examined the reading performance of a letter-by-letter reader, FH, over a period of 15 months, using eye movement methodology to delineate the recovery process at two different time points (T1, T2). A central question is whether recovery is characterized either by moving back towards normal word processing or by refinement and possibly automatization of an existing pathological strategy that was developed in response to the impairment. More specifically, we hypothesized that letter-by-letter reading may be executed with at least four different strategies and our work sought to distinguish between these alternatives. During recovery significant improvements in reading performance were achieved. A shift of fixation positions from the far left to the extreme right of target words was combined with many small and very few longer regressive saccades. Apparently, 'letter-by-letter reading' took the form of local clustering, most likely corresponding to the formation of sublexical units of analysis. This pattern was more pronounced at T2, suggesting that improvements in reading efficiency may come at the expense of making it harder to eventually return to normal reading.
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Affiliation(s)
- Irene Ablinger
- Department of Neuropsychology, RWTH Aachen University Hospital, Aachen, Germany.
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Roberts DJ, Woollams AM, Kim E, Beeson PM, Rapcsak SZ, Lambon Ralph MA. Efficient visual object and word recognition relies on high spatial frequency coding in the left posterior fusiform gyrus: evidence from a case-series of patients with ventral occipito-temporal cortex damage. ACTA ACUST UNITED AC 2012; 23:2568-80. [PMID: 22923086 PMCID: PMC3792736 DOI: 10.1093/cercor/bhs224] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent visual neuroscience investigations suggest that ventral occipito-temporal cortex is retinotopically organized, with high acuity foveal input projecting primarily to the posterior fusiform gyrus (pFG), making this region crucial for coding high spatial frequency information. Because high spatial frequencies are critical for fine-grained visual discrimination, we hypothesized that damage to the left pFG should have an adverse effect not only on efficient reading, as observed in pure alexia, but also on the processing of complex non-orthographic visual stimuli. Consistent with this hypothesis, we obtained evidence that a large case series (n = 20) of patients with lesions centered on left pFG: 1) Exhibited reduced sensitivity to high spatial frequencies; 2) demonstrated prolonged response latencies both in reading (pure alexia) and object naming; and 3) were especially sensitive to visual complexity and similarity when discriminating between novel visual patterns. These results suggest that the patients' dual reading and non-orthographic recognition impairments have a common underlying mechanism and reflect the loss of high spatial frequency visual information normally coded in the left pFG.
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Affiliation(s)
- Daniel J Roberts
- Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester, Manchester, UK
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Chang YN, Furber S, Welbourne S. Modelling normal and impaired letter recognition: implications for understanding pure alexic reading. Neuropsychologia 2012; 50:2773-2788. [PMID: 22841988 PMCID: PMC3657697 DOI: 10.1016/j.neuropsychologia.2012.07.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 07/18/2012] [Accepted: 07/21/2012] [Indexed: 11/24/2022]
Abstract
Letter recognition is the foundation of the human reading system. Despite this, it tends to receive little attention in computational modelling of single word reading. Here we present a model that can be trained to recognise letters in various spatial transformations. When presented with degraded stimuli the model makes letter confusion errors that correlate with human confusability data. Analyses of the internal representations of the model suggest that a small set of learned visual feature detectors support the recognition of both upper case and lower case letters in various fonts and transformations. We postulated that a damaged version of the model might be expected to act in a similar manner to patients suffering from pure alexia. Summed error score generated from the model was found to be a very good predictor of the reading times of pure alexic patients, outperforming simple word length, and accounting for 47% of the variance. These findings are consistent with a hypothesis suggesting that impaired visual processing is a key to understanding the strong word-length effects found in pure alexic patients.
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Affiliation(s)
- Ya-Ning Chang
- Neuroscience and Aphasia Research Unit (NARU), University of Manchester, Manchester M13 9PL, UK
| | - Steve Furber
- School of Computer Science, University of Manchester, Manchester M13 9PL, UK
| | - Stephen Welbourne
- Neuroscience and Aphasia Research Unit (NARU), University of Manchester, Manchester M13 9PL, UK.
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Number reading in pure alexia--a review. Neuropsychologia 2011; 49:2283-98. [PMID: 21554892 DOI: 10.1016/j.neuropsychologia.2011.04.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 03/31/2011] [Accepted: 04/22/2011] [Indexed: 11/23/2022]
Abstract
It is commonly assumed that number reading can be intact in patients with pure alexia, and that this dissociation between letter/word recognition and number reading strongly constrains theories of visual word processing. A truly selective deficit in letter/word processing would strongly support the hypothesis that there is a specialized system or area dedicated to the processing of written words. To date, however, there has not been a systematic review of studies investigating number reading in pure alexia and so the status of this assumed dissociation is unclear. We review the literature on pure alexia from 1892 to 2010, and find no well-documented classical dissociation between intact number reading and impaired letter identification in a patient with pure alexia. A few studies report strong dissociations, with number reading less impaired than letter reading, but when we apply rigorous statistical criteria to evaluate these dissociations, the difference in performance across domains is not statistically significant. There is a trend in many cases of pure alexia, however, for number reading to be less affected than letter identification and word reading. We shed new light on this asymmetry by showing that, under conditions of brief exposure, normal participants are also better at identifying digits than letters. We suggest that the difference observed in some pure alexic patients may possibly reflect an amplification of this normal difference in the processing of letters and digits, and we relate this asymmetry to intrinsic differences between the two types of symbols.
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Abstract
PURPOSE OF REVIEW Both monkey and human neuroimaging studies show that visual processing beyond the striate cortex involves a highly complex network of regions with modular functions. Lesions within this network lead to specific clinical syndromes. In this review we discuss studies on blindsight, which is the ability of remaining regions to support vision in the absence of striate cortex or visual awareness, recent work on 'ventral stream' syndromes such as object agnosia, alexia, prosopagnosia, and topographagnosia, which follow damage to medial occipitotemporal structures, and simultanagnosia, the classic 'dorsal stream' deficit related to bilateral occipitoparietal lesions. RECENT FINDINGS We highlight work on the anatomic basis of blindsight, the recent description of the new disorder developmental topographic disorientation, and studies contrasting global and local perception in simultanagnosia. SUMMARY These studies advance our understanding of the mechanisms of complex visual processing and provide an important neuropsychological complement to our expanding knowledge about vision from functional neuroimaging.
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