Visuographemic Alexia: A New Form of a Peripheral Acquired Dyslexia

Dalmás, J.Fernando; Dansilio, Sergio

doi:10.1006/brln.2000.2321

Cited by 18 publications

(15 citation statements)

References 41 publications

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“…These results may require postulation of separate left-and righthemisphere processes capable of digit identifi cation (e.g., Cohen 8c Dehaene, 1995;Dalmas 8c Dansilio, 2000;Miozzo 8c Caramazza, 1998); however, the results do not speak directly to the question of whether the (left-or right-hemi sphere) processes are shared between letter and digit identification. Cipolotti (1995) reported the case of an Alzheimer's dementia patient who was intact in letter identification and single-word reading, yet severely impaired in reading aloud Arabic numerals.…”

Section: Other Resultsmentioning

confidence: 67%

“…Half of the characters were real letters, and half were pseudo letters. The dissociation between impaired letter identi fication and intact letter decision has also been observed in other patients (e.g., Brunsdon, Coltheart, 8e Nickels, 2006;Caplan 80 HedleyWhyte, 1974;Chanoine, Teixeira Ferreira, Demonet, Nespoulous, 8c Poncet, 1998;Dalmas 8c Dansilio, 2000;Miozzo 8c Caramazza, 1998;Volpato, Bencini, Meneghello, Piron, 8c Semenza, 2012) and has been taken as evidence for a level of stored allograph representations prior to the level of abstract letter identities. As illustrated in Figure 4, Schubert and McCloskey (in press) proposed in particular that allograph rep resentations intervene between the character shape and abstract letter identity levels, such that charac ter shape representations first activate allograph representations, which in turn activate abstract letter identities.…”

Section: Letter Decision and Allograph Representationsmentioning

confidence: 58%

“…Several neuropsychological studies have reported intriguing dissociations within the digit realm, such that some aspects of a patient's per formance point to an impairment in digit identifi cation, whereas other aspects of performance suggest intact digit processing (e.g., Cohen 8c Dehaene, 1991, 1995Dalmas 8c Dansilio, 2000;Miozzo 8c Caramazza, 1998). These results may require postulation of separate left-and righthemisphere processes capable of digit identifi cation (e.g., Cohen 8c Dehaene, 1995;Dalmas 8c Dansilio, 2000;Miozzo 8c Caramazza, 1998); however, the results do not speak directly to the question of whether the (left-or right-hemi sphere) processes are shared between letter and digit identification.…”

Section: Other Resultsmentioning

confidence: 99%

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Shared versus separate processes for letter and digit identification

McCloskey

Schubert

2014

Cognitive Neuropsychology

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Letters and digits, although similar in many respects, also differ in potentially significant ways. Most importantly, letters are elements of an alphabetic writing system, whereas digits are logographs. In this article, we explore whether letters and digits are identified by a single character identification process that makes no fundamental distinction between the two types of characters, or whether instead letter and digit identification processes diverge at least in some respects. We present evidence from an acquired dyslexic patient, L.H.D., who is impaired in both letter and digit identification. Working within a theoretical framework specifying the levels of representation implicated in letter identification, we systematically compare L.H.D.'s letter and digit processing. The results provide evidence that letter and digit identification implicate the same levels of representation, and further that L.H.D.'s identification errors for both letters and digits arise at the same point in processing. On the basis of these results, we argue for a shared process that mediates identification of both letters and digits. Finally, we discuss relevant previous results in light of this conclusion.

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Section: Other Resultsmentioning

confidence: 67%

Section: Letter Decision and Allograph Representationsmentioning

confidence: 58%

Section: Other Resultsmentioning

confidence: 99%

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Shared versus separate processes for letter and digit identification

McCloskey

Schubert

2014

Cognitive Neuropsychology

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“…Several recent reports have described patients who are impaired at letter identification, yet nevertheless are able to distinguish real letters from other characters such as pseudoletters or misoriented letters (e.g., Brunsdon et al, 2006;Caplan & Hedley-Whyte, 1974;Chanoine et al, 1998;Dalmás & Dansilio, 2000;Miozzo & Caramazza, 1998;Volpato et al, 2012). We demonstrate that L.H.D.…”

Section: Allograph Representationssupporting

confidence: 45%

“…On the basis of the results, as well as findings from previous studies, we propose several significant elaborations and extensions of the Hillis (1990a, 1990b) theory. First, we build upon a growing body of work (e.g., Brunsdon, Coltheart, & Nickels, 2006;Caplan & Hedley-Whyte, 1974;Chanoine, Teixeira Ferreira, Demonet, Nespoulous, & Poncet, 1998;Dalmás & Dansilio, 2000;Miozzo & Caramazza, 1998;Rapp & Caramazza, 1989;Volpato, Bencini, Meneghello, Piron, & Semenza, 2012) that demonstrates the need to posit a level of representation not included in the original Caramazza and Hillis theory: an allograph level that represents each distinct visual form of a letter (e.g., g and G for the letter G). As well as showing that L.H.D.…”

Section: Goals Of the Studymentioning

confidence: 99%

Prelexical representations and processes in reading: Evidence from acquired dyslexia

Schubert¹,

McCloskey²

2013

Cognitive Neuropsychology

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We report a detailed and extensive single-case study of an acquired dyslexic patient, L.H.D., who suffered a left-hemisphere lesion as a result of a ruptured aneurysm. We present evidence that L.H.D.'s reading errors stem from a deficit in visual letter identification, and we use her deficit as a basis for exploring a variety of issues concerning prelexical representations and processes in reading. First, building on the work of other researchers, we present evidence that the prelexical reading system includes an allograph level of representation that represents each distinct visual shape of a letter (e.g., a, A, etc., for the letter A). We extend a theory proposed by Caramazza and Hillis [Caramazza, A., & Hillis, A. (1990a). Spatial representation of words in the brain implied by studies of a unilateral neglect patient. Nature, 346, 267-269] to include an allograph level, and we probe the nature of the allograph representations in some detail. Next, we explore the implications of visual similarity effects and letter perseverations in L.H.D.'s reading performance, arguing that these effects shed light on activation dynamics in the prelexical reading system and on the genesis of L.H.D.'s errors. We also probe the processing of letter case in the visual letter identification process, proposing that separate abstract letter identity and case representations are computed. Finally, we present evidence that the allograph level as well as the abstract letter identity level implement a word-based frame of reference.

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Posterior Cerebral Artery Disease

Binder¹,

Mohr²

2004

Stroke

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Visuographemic Alexia: A New Form of a Peripheral Acquired Dyslexia

Cited by 18 publications

References 41 publications

Shared versus separate processes for letter and digit identification

Shared versus separate processes for letter and digit identification

Prelexical representations and processes in reading: Evidence from acquired dyslexia

Posterior Cerebral Artery Disease

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