Japanese Dyslexia Research Articles

Writing Disorders of Children With Developmental Dyslexia in Japanese: Scale Construction and Examination of Cognitive Deficits and Subtypes

本研究は，小学校教員に対する質問紙調査により，（1）日本語のディスレクシア児の書字に関する特徴的な認知障害を包括的に検討すること，（2）それらの認知障害を測定する尺度を作成し，その信頼性・妥当性を検討すること，（3）日本語のディスレクシアの書字障害にはどのようなサブタイプが存在するのかを明らかにすること，（4）各々のサブタイプは読み書き能力とどのように関係しているのかを検討することを目的とした。書字特性の因子分析の結果から，日本語のディスレクシア児では書字に関して4つの主要な認知障害――心的辞書障害，視覚性障害，音韻性障害，書字運動障害――が存在すること，および，これらの認知障害を測定する「ディスレクシア児の書字障害尺度」（WDS-DC）は，信頼性・妥当性が高いことが示唆された。さらに，クラスタ分析により発達性書字障害のサブタイプを分析したところ，重度多重障害群，中度多重障害群，視覚処理障害群が存在することが示唆され，重度多重障害群と中度多重障害群は全ての文字種の読み書き能力において，視覚処理障害群，ボーダー群，障害なし群より低いことが示された。

Development of a reading difficulty questionnaire for adolescents in Japanese

BackgroundDyslexia is a neurodevelopmental disorder which occurs in childhood but continues to influence academic and occupational function in adulthood. Recently, a Japanese dyslexia questionnaire and diagnostic procedure was established for primary school children. However, there is currently no procedure for the diagnosis or screening of dyslexia in individuals at or above junior high school age; accordingly, we aimed to develop a questionnaire to screen for reading difficulties in those individuals. MethodsA questionnaire with various candidate items was developed from two English questionnaires, one Japanese questionnaire, and newly devised items focusing on the Japanese writing system and the most appropriate 28 items were selected. In total, 462 adults and 127 junior high to high school students were enrolled. Of those, 191 participants also took part in reading tests. After the exploratory factor analysis, reliability and validity were evaluated using the above control participants and 12 adolescents with dyslexia. ResultsThe questionnaire included three factors, i.e., silent reading sub-scale (four items), writing sub-scale (four items), and aloud reading sub-scale (three items). Five were newly devised items focusing on the Japanese writing system. Cronbach’s alphas of the three factors were 0.706, 0.638, and 0.568, respectively, and the interclass correlation coefficients (2,1) were 0.743, 0.609, and 0.695, respectively. The silent reading and aloud reading sub-scales were positively correlated with word, non-word, and passage reading time. DiscussionThe newly developed questionnaire correlated well with actual reading performance and may be used to screen reading difficulty in Japanese individuals at or above junior high school age.

A Review of the Bi-Passing Training Method and Its Efficacyfor Children with Developmental Dyslexia in Japanese

A Review of the Bi-Passing Training Method and Its Efficacyfor Children with Developmental Dyslexia in Japanese

Eye fixation patterns and saccades of children with dyslexia in Japanese

Eye fixation patterns and saccades of children with dyslexia in Japanese

Developmental Reading Disorders in Japan—Prevalence, Profiles, and Possible Mechanisms

Japan has been considered dyslexia-free because of the nature of the orthography, which consists of the visually simple kana syllabary and some thousands of visually complex, logographic kanji characters. It is true that few children struggle with learning kana, which provide consistent mappings between symbols and their pronunciation. Indeed, most children can read most of the kana by age 6. However, many Japanese children struggle with reading the kanji, which represent most of the content words in a text; in addition to their visual complexity and impoverished or nonexistent phonological information, kanji are difficult because they typically have several pronunciations and multiple meanings, depending on the context. Because kanji must be learned semantically rather than phonologically, many people believe that Japanese dyslexia is due to visuospatial rather than phonological processing impairments. We sketch the complex psycholinguistic demands of retrieving the correct pronunciations for kanji, especially in kanji compound words. Some individuals have extreme difficulty in learning the correspondences between these symbols and their sounds; whether these difficulties are visual, phonological, or both is an urgent topic for further research. After introducing Japanese orthography, we present 2 case studies. The first is a profile of a boy we observed from ages 7 to 20 years with difficulties in learning both kana and kanji. The second is a case study of using an interactive reading intervention for a fifth-grade boy with dyslexia. This program was designed to reduce decoding and fluency problems by teaching the meanings and pronunciations in phrasal context rather than in vocabulary lists. We propose that some of the dyslexias in Japanese may not be the same as any type of dyslexia that has been reported for learners of alphabetic writing systems. In addition, we emphasize the need for SLPs in Japan to establish new policies that support collaborative relationships with teachers and other professionals so that they can work in schools to identify and help children with spoken and written language problems.

Characteristics of Developmental Dyslexia in Japanese Kana from the Viewpoint of the Japanese Feature

This study identified the individual differences in the effects of Japanese Dyslexia. The participants consisted of 12 Japanese children who had difficulties in reading and writing Japanese and were suspected of having developmental disorders. A test battery was created on the basis of the characteristics of the Japanese language to examine Kana’s orthography-to-phonology mapping and target four cognitive skills: analysis of phonological structure, letter-to-sound conversion, visual information processing, and eye–hand coordination. An examination of the individual ability levels for these four elements revealed that reading and writing difficulties are not caused by a single disability, but by a combination of factors. Additionally, the combination of individual elements differed among the participants, which indicates that children with learning disabilities may need different types of support even if they have similar reading and writing difficulties. Furthermore, this study demonstrated that words written in Kana, one of the Japanese syllabic, are easy to segment into phonological units, but difficult to interpret when attempting to link each letter to its corresponding sound. These findings can help change the concept of Japanese dyslexia and have a significant impact on education methods and techniques in Japan.

Altered brain activity for phonological manipulation in dyslexic Japanese children.

Because of unique linguistic characteristics, the prevalence rate of developmental dyslexia is relatively low in the Japanese language. Paradoxically, Japanese children have serious difficulty analysing phonological processes when they have dyslexia. Neurobiological deficits in Japanese dyslexia remain unclear and need to be identified, and may lead to better understanding of the commonality and diversity in the disorder among different linguistic systems. The present study investigated brain activity that underlies deficits in phonological awareness in Japanese dyslexic children using functional magnetic resonance imaging. We developed and conducted a phonological manipulation task to extract phonological processing skills and to minimize the influence of auditory working memory on healthy adults, typically developing children, and dyslexic children. Current experiments revealed that several brain regions participated in manipulating the phonological information including left inferior and middle frontal gyrus, left superior temporal gyrus, and bilateral basal ganglia. Moreover, dyslexic children showed altered activity in two brain regions. They showed hyperactivity in the basal ganglia compared with the two other groups, which reflects inefficient phonological processing. Hypoactivity in the left superior temporal gyrus was also found, suggesting difficulty in composing and processing phonological information. The altered brain activity shares similarity with those of dyslexic children in countries speaking alphabetical languages, but disparity also occurs between these two populations. These are initial findings concerning the neurobiological impairments in dyslexic Japanese children.

Dyslexia: Advances in clinical and imaging studies

The aim of this report is to describe the characteristics of Japanese dyslexia, and to demonstrate several of our studies about the extraction of these characteristic and their neurophysiological and neuroimaging abnormalities, as well as advanced studies of phonological awareness and the underlying neural substrate. Based on these results, we have proposed a 2-step approach for remedial education (e-learning web site: http://www.dyslexia-koeda.jp/). The first step is decoding, which decreases reading errors, and the second is vocabulary learning, which improves reading fluency. This 2-step approach is designed to serve first grade children. In addition, we propose the RTI (response to intervention) model as a desirable system for remedial education.

The association between semantic dementia and surface dyslexia in Japanese

One theory about reading suggests that producing the correct pronunciations of written words, particularly less familiar words with an atypical spelling–sound relationship, relies in part on knowledge of the word's meaning. This hypothesis has been supported by reports of surface dyslexia in large case-series studies of English-speaking/reading patients with semantic dementia (SD), but would have increased credibility if it applied to other languages and writing systems as well. The hypothesis predicts that, of the two systems used to write Japanese, SD patients should be unimpaired at oral reading of kana because of its invariant relationship between orthography and phonology. By contrast, oral reading of kanji should be impaired in a graded fashion depending on the consistency characteristics of the kanji target words, with worst performance on words whose component characters take ‘minority’ (atypical) pronunciations, especially if the words are of lower frequency. Errors in kanji reading should primarily reflect assignment of more typical readings to the component characters in these atypical words. In the largest-ever-reported case series of Japanese patients with semantic dementia, we tested and confirmed this hypothesis.

The association between semantic dementia and surface dyslexia in Japanese

The association between semantic dementia and surface dyslexia in Japanese

Surface dyslexia in a Japanese patient with semantic dementia: evidence for similarity-based orthography-to-phonology translation

We studied the reading performance of a Japanese-speaking patient, TI, with bilateral but asymmetrical (left more than right) temporal-lobe atrophy, severe anomia, and poor word comprehension. Most Japanese kanji characters correspond to several different legitimate pronunciations in different contexts, with varying degrees of correspondence consistency. TI made many errors in reading aloud words that violate statistically typical character-sound correspondences, especially for less common words, but had relatively preserved ability to read aloud strings in which the assignment of the typical pronunciation for each component character yields the correct pronunciation for the whole word. The degree of consistency of character-sound correspondences affected his performance on both words and nonwords in a graded manner. One interpretation is that TI’s surface dyslexic reading reflects intact direct computation of phonology from orthography, but without the additional constraint from word meaning that is, in this framework, considered critical for correct pronunciation of lower-frequency words with atypical character-sound correspondences. Another interpretation is that TI’s performance reflects partially damaged lexical knowledge of whole-word orthography and phonology, coupled with spared sublexcal knowledge of character-sound correspondence rules. Whichever of these interpretations is preferred, this study offers the most detailed information yet available on the characteristics of surface dyslexia in Japanese.

Cognitive and neurophysiological evaluation of Japanese dyslexia.

Seven Japanese dyslexic boys were evaluated as to their pedagogic performance on the pupil rating scale (PRS), and psychological and neurophysiological characteristics. One of them suffered from severe English dyslexia despite that his Japanese dyslexia was feeble. PRS did not successfully reveal their reading difficulties. Psychological examination (WISC-R and K-ABC) revealed their cognitive dysfunction, but the results were heterogeneous. The Token test was most useful for detecting their poor reading comprehension. Electroencephalogram (EEG) coherence analysis showed high inter- and intra-hemispheric values. These findings may imply hyperconnectivity of the cerebral white matter in dyslexia. We assumed that the Token test demonstrates the discrepancy between reading and hearing comprehension best of all among these psychological tests and that connectivity between non-functional cortical lesions remains in dyslexic children.

Dissociations Between Reading Responses and Semantic Priming Effects in A Dyslexic Patient

We report a patient (Y.Y.) with senile dementia of the Alzheimer's type. The patient read aloud some words composed of two or three kanji characters with errors applying typical pronunciations of each character and defined them in keeping with the mispronunciation if the pronunciation represented another real word. The results of single-word semantic priming in a lexical decision task, however, suggested normal recognition processes for these kanji-words, despite the patient's reading errors. We consider her reading to represent surface dyslexia in Japanese. We discuss these dissociations between reading responses and priming effects in the context of dual-route models of human reading, and conclude that the “visual route” (direct access from orthography to semantics and phonology) was not completely disrupted, but partially preserved and functioning in automatic access.

A test of a hypothesis of automatic phonological processing of Kanji words

This paper aims to examine a hypothesis that phonological processing should occur in Japanese Kanji words as well as in Kana words, but automatic in Kanji words. In Experiment 1, subjects performed concurrent articulation or finger tapping during a semantic processing task of Kana words with 2 to 4 phonemes, for which phonological processing should be indispensable. Concurrent articulation was found to eliminate the phoneme number effect found in the control condition, but finger tapping was not. This result indicates the effectiveness of concurrent articulation in articulatory suppression. In Experiment 2, the materials were changed to Kanji words, for which phonological processing had been supposed to be dispensable, and subjects performed the same task. The results showed no phoneme number effect even in the control condition, and the reaction time in the concurrent articulation condition was delayed significantly. These results suggest the existence of automatic phonological processing of Kanji words. Finally, the pertinence of this hypothesis was confirmed by applying it to the explanations of 3 kinds of Japanese dyslexia.

Developmental Deep Dyslexia in Japanese: A Case Study

This report demonstrates the existence of developmental deep dyslexia involving Japanese orthography. When asked to read (or name) isolated kanji, T.S., a sixth grader with a normal IQ and no speech impairment, produced a number of visual, selection, and semantic errors. It is suggested that these errors arise from an interaction between phonological coding impairment and the relative sparing of direct visual processing, which are taken to be characteristic of developmental deep dyslexia. A selection hypothesis is presented to explain selection errors, semantic errors, and some peculiar phenomena observed in acquired dyslexics.