Torleiv Høien

MRI evaluation of the size and symmetry of the planum temporale in adolescents with developmental dyslexia

MRI technique was used to examine the size and symmetry of the plana temporale in 19 dyslexic students in grade 8 and in carefully matched control subjects. The results demonstrated a high frequency of planum symmetry among the dyslexics (70%) whereas symmetry was observed in only 30% of the control subjects. It was not possible to demonstrate any clear association between symmetry/asymmetry of planum temporale and handedness. Word-reading strategies among the dyslexics and control subjects were investigated with computerized tasks where accuracy and naming latency were recorded. All subjects with pure phonological deficits in reading had symmetrical plana temporale indicating a possible neuroanatomical basis for a characteristic symptom of linguistic processing deficiency in developmental dyslexia.

Components of phonological awareness

The factorial structure underlying different types of tasks within the domain of phonological awareness was examined in two studies. Large sample sizes allowed for sensitive differentiation of constructs. In the first study, 128 preschool children without any experience of formal reading instruction were tested with a battery of tasks intended to tap various aspects of phonological awareness: rhyme recognition, syllable counting, initial-phoneme matching, initial-phoneme deletion, phoneme blending, and phoneme counting. Three basic components were extracted in a principal component analysis: a phoneme factor, a syllable factor and a rhyme factor. Cross-tabulations indicated considerable dissociation between performance on phoneme, syllable, and rhyme tasks. The structural relationships were replicated on a much larger sample (n=1509) in the second study. Subjects in this study were one year older and were attending grade 1 thus providing an opportunity to test their reading achievement. Multiple regression analyses demonstrated that the phonemic factor was by far the most potent predictor. However, the rhyming factor made an independent (although small) contribution to explaining the reading variance. Among the phonemic tasks, phoneme identification proved to be the most powerful predictor.

Dyslexia : From Theory to Intervention

Preface. 1. What is Dyslexia? 2. Decoding Difficulties - A Major Symptom of Dyslexia. 3. Spelling Difficulty: A Major Symptom of Dyslexia. 4. Dyslexia and Phonology. 5. Dyslexia and Reading Comprehension. 6. The Biological Basis of Dyslexia. 7. Assessment and Diagnosing. 8. Remediation. References. Author Index. Subject Index.

Magnetic resonance imaging of the corpus callosum in developmental dyslexia

Abstract The cerebral anatomy of reading processing in normals and developmental dyslexics is incompletely understood. However, the core problem of developmental dyslexia seems to be located in the word recognition aspect of reading. Most probably, normal reading involves right-hemisphere cerebral functions in addition to the more important left-hemisphere functions. The major communicator between the hemispheres is the corpus callosum and the splenium of the corpus callosum, in particular, may be involved in efficient word processing. In this study we could not find any gross differences in size of the total corpus callosum or the splenium between groups of dyslexics and controls. Furthermore, we could not find any abnormalities in size of the corpus callosum in subgroups of dyslexia related to gender, linguistic deficiencies, or symmetry/asymmetry of the planum temporale.

Phonemic Deficits: A Core Symptom of Developmental Dyslexia?

The basic weakness in developmental dyslexia is lack of facility with words. Instead of searching for various behavioural, educational or social correlates of this deficiency, we analysed the critical cognitive and linguistic demands raised by the alphabetical code. Dyslexic children suffer from poor access to the phonemic units of spoken language and this lack of phonemic awareness is then a serious obstacle in the process of reading acquisition. A longitudinal study of children from preschool to the end of grade 3 clearly demonstrated that a speciflc phonemic deficiency already exsisted before starting school among 35 dyslexics. The poor reading and spelling development observed among these children was interpreted as causally related to their problems with the elusive and abstract phonemes. In a second study with dyslexic adolescents we looked for the biological basis of poorly developed phonological skills. Strong tendencies of phonological difficulties were observed in families of dyslexics. Magnetic...

Phonological skills and reading comprehension

In the present study the mainfocus is on the impact of phonologicalawareness on reading comprehension. The studyinvolved 1300 children in Grade 1. Syllableawareness, phoneme awareness, word decodingand reading comprehension were each assessedwith two or three subtests. The results wereanalyzed by structural modeling. Due to themarked skewness observed for some of themanifest variables, separate analyses wereperformed for students with average worddecoding performance and for students with poorword decoding. Both among average and poordecoders, phonological awareness had a directimpact on reading comprehension, indicatingthat phonological factors play an independentrole in the processing of text. One possibleway to explain this observation is that atleast two critical factors in comprehension,vocabulary and short-term memory, are bothdetermined in part by phonological ability. Itmight also be the case that phonologicalawareness partly reflects metacognitiveprocesses assumed to be involved in readingcomprehension.

Initial Enabling Knowledge and Skills in Reading Acquisition: Print Awareness and Phonological Segmentation

The acquisition of reading skill does not begin with formal instruction in school. Throughout the preschool years, most children in Western societies are subjected to a great deal of informal literacy socialization. Although a majority of children enter school as nonreaders in a traditional sense, they often display surprisingly well-developed concepts of the nature and the function of written language. A skill component, however, also is involved in reading literacy, which does not easily seem to develop spontaneously in the natural ecology of a child, but which, in many cases, seems to require explicit teaching for its development. The purpose of this chapter is to discuss some of the important steps preschool children seem to take on the route to literacy and to review some empirical studies that especially reveal the critical importance of phonological awareness in reading acquisition.

A Strategy for Assessing Problems in Word Recognition among Dyslexics

Abstract The article argues for the importance of studying word‐recognition strategies in the assessment of dyslexia. The consensus model of word recognition in cognitive neuropsychology, the dual‐route model, is critically discussed in the light of attacks from computational models in modern connectionism. Despite the criticism, it is argued that a dual‐route model can serve important functions in the context of dyslexia assessment. We propose a specific version of the dual‐route model from which we construct a series of tasks for diagnosing subprocesses in word recognition. A computer‐based test battery is described, involving oral reading tasks, lexical decision, rhyme detection, letter categorization, visual analysis, naming, and semantic categorization. Latencies and accuracy scores are recorded. The usefulness of this assessment approach is demonstrated in two case studies of 15‐year‐old dyslexic boys.

Early phonological skills as a predictor of reading acquisition: A follow-up study from kindergarten to the middle of grade 2

The purpose of this study was to investigate the power of early measures of phonological skills (phonemic awareness, rapid naming, short-term memory) in predicting later reading skills at various points of time. About 70 children were followed from the end of kindergarten to the middle of grade 2. Correlation analyses were performed as well as a linear growth curve analyses. In the traditional regression analysis, phonemic awareness in kindergarten explained about 27% of the variance in word reading six months later and about 9.5% of the variance at the end of grade 1. Even when prior level of reading skill was included in the predictive equation, a significant amount of variance was still explained by phonemic awareness. The other predictor variables did not explain any variance in word reading, and phonemic awareness did not predict any variance in reading skills in grade 2. When using sentence reading as the dependent variable, phonemic awareness explained about 16% of unique variance after six months, and about 13% of the variance in the middle of grade 2. Similarly, when employing growth curve analysis, phonemic awareness was the only phonological factor that accounted for significant variance in the word reading slope, explaining about 25% of its variance, whereas naming and short-term memory did not explain any unique variance. The lack of predictive power of phonemic awareness on the sentence b-slope is assumed to be caused by unreliable sentence scores in kindergarten.

What is Dyslexia

Anyone who visits a classroom will notice striking differences among the students, both physical and mental differences, despite the fact that the students are all the same age. Differences in temperament, motor skills, drawing skills, interests, reading ability, self-confidence, mathematics ability, verbal skills, and the like, are clearly evident. It is no easy task for a teacher to devise lessons that will accommodate every student in a given class.