Deep Dyslexia Research Articles

Chapter 16 - Acquired dyslexias following temporal lesions

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.

Bigraph-syllable blending therapy in deep dyslexia

ABSTRACT Background: The evidence-base of therapy studies for reading difficulties is notably sparse, particularly for individuals with deep dyslexia. Research using grapheme-to-phoneme correspondence approaches to remediate the non-lexical reading route in deep dyslexia have been reported but with limited therapy success. The approach of bigraph-syllable blending training has met with some success enabling individuals with deep dyslexia to read single words containing these bigraphs. Aims: This study compares the effects of the bigraph-syllable pairing training method on oral reading for mid-high and low-frequency bigraphs in training and generalization items in an individual with deep dyslexia (DT). To inform the clinical practice, we also analysed DT’s ability to engage with the therapy cues (i.e. ability to process, generate and utilize the cues) to determine the most responsive component of the cueing hierarchy. Methods & Procedures: Detailed assessment indicated that DT showed deep dyslexia with severe difficulties reading non-words, alongside imageability effects and production of semantic errors. A single-subject multiple probe across behaviour design was employed to evaluate the efficacy of bigraph-syllable pairing therapy for training and generalization of bigraph sets containing mid-high and low-frequency bigraphs. DT’s engagement with the therapy cues were tracked across each of the therapy sessions. Generalisation effects were evaluated by measuring performance on untrained bigraph stimuli and change in performance from pre- to post-therapy on single word reading subtests. Outcomes & Results: Results reveal that post-therapy DT showed improvement in reading aloud for both mid-high and low frequency trained bigraphs, albeit to a different degree. Mid-high frequency bigraphs showed greater therapy effects than the low-frequency bigraphs. DT demonstrated that writing and copying were the most beneficial cues in supporting DT’s oral reading of bigraphs. He did not show any generalization to untrained bigraphs, but illustrated a reduction in imageability effects with improved reading accuracy for low-imageability single words, and improved ability to name letters. Post-therapy, he showed a significant reduction in omission errors and a significant increase in unclassifiable errors in reading aloud. Conclusions & Implications: This study demonstrated the efficacy of bigraph-syllable pairing training for improving oral reading abilities and reducing the imageability effects in an individual with deep dyslexia. The findings from client’s responsiveness with different cues during the therapy showed that writing and coping is a useful strategy for improving reading aloud abilities.

Semantic processing of metaphor: A case-study of deep dyslexia

Abstract Deep dyslexia is characterized by the production of semantic errors (e.g., reading the word weird aloud as odd) during oral reading and greater difficulty reading aloud abstract words than concrete words. In this paper, we examine whether deep dyslexia affects higher-order semantic processing; namely, metaphor comprehension. To that end, we asked GL, a participant with deep dylexia, to rate novel metaphors (e.g., language is a bridge) for comprehensibility. The topics of the metaphors (e.g., “language” in the item above) varied on concreteness, such that they were either abstract or concrete. Also, the semantic neighbourhood density (SND) of the constituent nouns (e.g., “language”, “bridge”) was manipulated. In addition to metaphors, GL also rated literal (e.g., a gorilla is an ape) and semantically anomalous sentences (e.g., arrival is a shoestring). GL rated the literal sentences as maximally comprehensible and he also rated the abstract-low SND metaphors as comprehensible. However, other, more semantically rich metaphors (i.e., those with concrete constituents or high-SND constituents) were treated as non-comprehensible with ratings indistinguishable from ratings given to anomalous sentences. We discuss how GL’s data align with models of deep dyslexia and metaphor processing.

Concrete and abstract word processing in deep dyslexia

Abstract The purpose of this case study was to test the failure of inhibition theory of deep dyslexia (FIT; Buchanan, McEwen, Westbury, & Libben, 2003) with concrete and abstract words. FIT proposes that in deep dyslexia, errors to abstract words are the result of an impairment in phonological output lexicon selection rather than a semantic deficit for abstract words. FIT also proposes a dissociation between explicit phonological lexicon production (can be compromised) and implicit access of representations (is intact). With such assumptions it follows that in phonologically implicit tasks where controls demonstrate either concreteness or abstractness effects, a participant with deep dyslexia would similarly show concreteness or abstractness effects. However, for explicit tasks where production is involved, a participant with deep dyslexia would only show concreteness effects due to difficulty with abstract word production, indicative of their difficulty with phonological output lexicon selection which is more compromised for abstract words because semantic content cannot guide the selection. Experiments 1–3 used phonologically implicit tasks (i.e., concrete categorization task, semantic relatedness task, and iconicity judgment task) and Experiment 4 used an explicit task (i.e., oral word-reading task). The results supported the hypotheses and are consistent with FIT as an explanation for the locus of impairment in deep dyslexia.

Orthographic connectivity in Arabic reading: a case study of an individual with deep dyslexia and letter-by-letter reading

ABSTRACTArabic orthography is complex, partly as a consequence of variations in orthographic connectivity. In this article, we present the case study of CHS, an Arabic individual with deep dyslexia associated with letter-by-letter reading. In the experimental study, we specifically explored the influence of orthographic connectivity on CHS’s word recognition and reading abilities. Our results show that CHS’s performance was better preserved for words and non-words made up of connected letters than made up of non-connected letters. CHS demonstrated impairment of visuoperceptual mechanisms, which affected the processing of complex orthographic material. These results provide insight into the cognitive processes associated with reading Arabic.

The Initial Blueprint of Errors Similar to the Phenomenon of Deep Dyslexia: As Reflected By Children With Dyslexia During Reading Hindi Words

The Initial Blueprint of Errors Similar to the Phenomenon of Deep Dyslexia: As Reflected By Children With Dyslexia During Reading Hindi Words

Acquired Dysgraphia in Arabic Orthography: A Case-Series Analyses

Acquired Dysgraphia in Arabic Orthography: A Case-Series Analyses

Applicability of dual-route reading models to Spanish.

Two opposing points of view have been presented with regard to the applicability of the dual-route reading models Spanish. Some authors maintain that, given the transparency of the reading system, non-lexical reading is the strategy followed predominantly by Spanish readers and for that reason these models are not appropriate to explain alexias (acquired dyslexias) in Spanish. Other authors, consider that since several cases of phonological, surface and deep alexia have been reported, dual-route reading models are applicable to Spanish in the same way that to the irregular writing systems. In order to contrast these two points of view, an analysis of the two main factors that influence the reading is made: characteristics of the Spanish orthography and characteristics of the Spanish readers. It is conclude that, (1) Due to its transparency, non-lexical reading represents -as in other transparent orthographies-- the initial reading strategy in Spanish; (2) the "reading threshold" (i.e., time required to become literate) is lower in Spanish because there are no irregular words to learn; (3) as reading experience increases, speed increases and lexical reading becomes used more; (4) Given the characteristics of the Spanish reading system, it is understandable that frequency of deep dyslexia is so low.

Prefixed words are produced similarly to compounds but not to suffixed words: Evidence from a case of deep dyslexia

Prefixed words are produced similarly to compounds but not to suffixed words: Evidence from a case of deep dyslexia

The influence of visual word form in reading: single case study of an Arabic patient with deep dyslexia

Deep dyslexia is a written language disorder characterized by poor reading of non-words, and advantage for concrete over abstract words with production of semantic, visual and morphological errors. In this single case study of an Arabic patient with input deep dyslexia, we investigated the impact of graphic features of Arabic on manifestations of reading impairments through experimental tasks. Semitic languages like Arabic have particular graphic features allowing the assessment of the influence of global word form on manifestations of deep dyslexia. Our results suggest that reading Arabic relies on the global visual word form when the phonological route no longer functions, as in deep dyslexia.

Classifying Chinese children with dyslexia by dual-route and triangle models of Chinese reading.

This present study focuses on classifying developmental dyslexia by combining two famous models, the dual-route model and the triangle model of Chinese reading, re-examining validity of the subtypes, and observing the error types of word recognition for each subtype. Sixty-sixth graders with dyslexia in Chinese and 45 sixth graders who were matched by age and IQ with the dyslexic group were involved in the present study. Twelve (20%) sixth graders from the dyslexic group were classified as having phonological dyslexia, 11 (18.3%) were classified as surface dyslexia, 12 (20%) were classified as deep dyslexia, and five (8.3%) of them were classified as displaying more than one kind of deficit. Besides, still more than half (31; 51.7%) of the dyslexic group did not belong to any subtypes here. These subtypes had a good validity based on comparison of their phonological awareness, orthography, and semantics. Finally, for their error types of word recognition, both children with multiple-deficit dyslexia and children with non-subtype dyslexia showed a proportional pattern of six kinds of errors. Children with phonological dyslexia showed more phonetic errors and analogy errors, children with surface dyslexia showed more visual errors and analogy errors, and children with deep dyslexia showed more semantic errors and selective errors.

The anatomical foundations of acquired reading disorders: A neuropsychological verification of the dual-route model of reading

In this study we investigated the neural correlates of acquired reading disorders through an anatomo-correlative procedure of the lesions of 59 focal brain damaged patients suffering from acquired surface, phonological, deep, undifferentiated dyslexia and pure alexia. Two reading tasks, one of words and nonwords and one of words with unpredictable stress position, were used for this study. We found that surface dyslexia was predominantly associated with left temporal lesions, while in phonological dyslexia the lesions overlapped in the left insula and the left inferior frontal gyrus (pars opercularis) and that pure alexia was associated with lesions in the left fusiform gyrus. A number of areas and white matter tracts, which seemed to involve processing along both the lexical and the sublexical routes, were identified for undifferentiated dyslexia. Two cases of deep dyslexia with relatively dissimilar anatomical correlates were studied, one compatible with Coltheart’s right-hemisphere hypothesis (1980) whereas the other could be interpreted in the context of Morton and Patterson’s (1980), multiply-damaged left-hemisphere hypothesis. In brief, the results of this study are only partially consistent with the current state of the art, and propose new and stimulating challenges; indeed, based on these results we suggest that different types of acquired dyslexia may ensue after different cortical damage, but white matter disconnection may play a crucial role in some cases.

Does argument structure complexity affect reading? A case study of an Italian agrammatic patient with deep dyslexia

ABSTRACTThe argument structure complexity hypothesis (Thompson, 2003) was introduced to account for the verb production pattern of agrammatic patients, who show greater difficulty in producing transitive versus unergative verbs (argument number effect) and in producing unaccusative versus unergative verbs (syntactic movement effect). The present study investigates these two effects in the reading performance of a patient (GR) suffering from deep dyslexia. GR read nouns significantly better than verbs; moreover, her performance was better on unergative than on transitive verbs, whereas the comparison between unergative and unaccusative verbs did not differ significantly. Data support the extension of the argument structure complexity hypothesis to word naming and suggest that the two aspects of argument structure complexity occur at different levels within models of lexical processing.

Thalamic semantic paralexia

Alexia may be divided into different subtypes, with semantic paralexia being particularly rare. A 57 year old woman with a discreet left thalamic stroke and semantic paralexia is described. Language evalution with the Boston Diagnostic Aphasia Battery confirmed the semantic paralexia (deep alexia). Multimodality magnetic resonance imaging brain scanning excluded other cerebral lesions. A good recovery ensued.

Progressive aphasia presenting with deep dyslexia and dysgraphia

Primary progressive aphasia is clinically heterogeneous. We report a patient, alias Don, with a novel form of progressive aphasia, characterised by deep dyslexia and dysgraphia and dissociated access to phonological and orthographic word forms. The hallmarks of deep dyslexia and dysgraphia were present early in the course and persisted over time. Writing was initially poorer than reading, but this reversed over time. There was a lack of concordance between reading and writing errors. Don benefited from a semantic mediation strategy to learn letter sounds, involving associating letters with a country name (e.g., A=Afghanistan). Remarkably, he continued to be able to generate those phonologically complex country names when no longer able to name or sound letters. Don’s performance is compatible with a traditional dual-route account of deep dyslexia and dysgraphia. The findings have potential practical implications for speech and language therapy in progressive aphasia. Moreover, they illustrate both the remarkable specificity yet clinical diversity in presentation of progressive aphasia.

The multiple-lemma representation of Italian compound nouns: A single case study of deep dyslexia

It is not clear how compound words are represented within the influential framework of the lemma-lexeme theory. Theoretically, compounds could be structured through a multiple lemma architecture, in which the lemma nodes of both the compound and its constituents are involved in lexical processing. If this were the case, syntactic properties of both the compound and its constituents should play a role when performing tasks involving compound processing, e.g., compound-word reading. This issue is investigated in the present study through an assessment of the performance of a deep dyslexic patient (GR) in three compound-reading experiments. In the first experiment, verb–noun (VN) compound nouns (e.g., lavapiatti, “dishwasher”, lit. wash-dishes) were employed as stimuli, while in the second, VN compound stimuli were embedded in sentences, and were compared to paired verb phrases (e.g., lui lava piatti, “he washes dishes”). Position-specific effects were ruled out by means of a third experiment, which investigated the retrieval of noun-noun compounds (e.g., pescespada, “swordfish”, lit. fishsword). In experiment 1, GR made errors on the verb constituent more frequently than on the noun, an effect that did not emerge in Experiment 2: when embedded in sentences, VN compounds were read significantly better than verb-phrases and no grammatical-class effect emerged. In Experiment 3, the first and the second constituent were read with the same level of accuracy. The disproportionate impairment, which emerged in reading the verb component of nominal VN compounds, indicates that the grammatical properties of constituents are being retrieved, and thus confirms access to the constituent lemma-nodes. However, the results suggested a whole-word representation when compounds are embedded in sentences; since the sentence context affects the access to compounds through syntactic constraints, whole-word representation is arguably at the lemma level as well (multiple-lemma representation). Experiment 3 indicates that these effects cannot be accounted for by a position-specific impairment.

Acquired Dyslexia in a Transparent Orthography: An Analysis of Acquired Disorders of Reading in the Slovak Language

The first reports of phonological, surface and deep dyslexia come from orthographies containing quasi-regular mappings between orthography and phonology including English and French. Slovakian is a language with a relatively transparent orthography and hence a mostly regular script. The aim of this study was to investigate impaired oral reading in Slovakian. A novel diagnostic procedure was devised to determine whether disorders of Slovakian reading resemble characteristics in other languages. Slovakian speaking aphasics showed symptoms similar to phonological dyslexia and deep dyslexia in English and French, but there was no evidence of surface dyslexia. The findings are discussed in terms of the orthographic depth hypothesis.

Acquired dyslexia in a transparent orthography: an analysis of acquired disorders of reading in the Slovak language.

The first reports of phonological, surface and deep dyslexia come from orthographies containing quasi-regular mappings between orthography and phonology including English and French. Slovakian is a language with a relatively transparent orthography and hence a mostly regular script. The aim of this study was to investigate impaired oral reading in Slovakian. A novel diagnostic procedure was devised to determine whether disorders of Slovakian reading resemble characteristics in other languages. Slovakian speaking aphasics showed symptoms similar to phonological dyslexia and deep dyslexia in English and French, but there was no evidence of surface dyslexia. The findings are discussed in terms of the orthographic depth hypothesis.

Contrasting Graded Effects of Semantic Similarity and Association across the Concreteness Spectrum

Evidence from healthy individuals and neuropsychological patients with deep dyslexia or semantic refractory access dysphasia suggests that abstract and concrete concepts have different dependencies upon associative and similarity-based representational frameworks. However, the importance of information about semantic similarity for concepts that lie across the full concreteness spectrum has not been investigated. Here we report the performance of healthy individuals on an odd-one-out task involving semantically related word triplets that showed continuous variation for the key variables of concreteness, similarity strength, and association strength. In addition, data from a stroke aphasic patient tested on a matching-to-sample task based on the same abstract, middle-concreteness, and concrete stimuli are also presented. The effects of similarity and association strength upon performance were both shown to interact significantly with concreteness, but in opposite directions. The effect of semantic similarity increased with concreteness but the effect of association decreased with concreteness. This research provides further evidence for the proposal that abstract and concrete words have different dependencies upon associative and similarity-based information. It also develops the proposal by providing data that are consistent with a graded and not binary or ungraded model of the relationship between concreteness and these two forms of semantic relationship.

More evidence for a continuum between phonological and deep dyslexia: Novel data from three measures of direct orthography-to-phonology translation

Background: Over recent years a number of studies have suggested that phonological and deep dyslexia are not separate acquired dyslexias but actually reflect different points along a single continuum. Behaviourally this continuum was originally defined in terms of the graded presence/absence of the “symptoms” of deep dyslexia. Aims: Given that orthography → phonology translation is core to phonological-deep dyslexia, it becomes critical to measure the degree and nature of any such direct phonological activation in these patients. Nonword reading accuracy has been the most commonly used measure of the status of direct orthographic → phonological activation but this measure can floor out in many phonological-deep dyslexic patients. In such circumstances, however, researchers have found evidence for some residual O→P function using reading tasks that do not require overt production—and these tasks might provide an important set of additional measures to test for a gradation of performance at the severer end of the phonological-deep dyslexic continuum. Methods & Procedures: In the present study three tasks of this type (spoken-to-written nonword-matching, a novel word-matching task, and pseudohomophone reading) were developed and tested in a case-series of phonological-deep dyslexia (and made available in the appendices to this paper). Outcomes & Results: As suggested from past studies, even patients with severely impaired overt nonword reading exhibited above-chance performance on the matching task and a pseudohomophone effect. The accuracy on these tasks varied in a graded manner across the case-series. Conclusions: Two factors are key to this dyslexia continuum: the severity of phonological impairment and also the degree of interaction between semantic and impaired phonological representations, indicating that semantic representations become more central to reading in the face of phonological impairment.