Reading acquisition, developmental dyslexia, and skilled reading across languages: a psycholinguistic grain size theory

The development of reading depends on phonological awareness across all languages so far studied. Languages vary in the consistency with which phonology is represented in orthography. This results in developmental differences in the grain size of lexical representations and accompanying differences in developmental reading strategies and the manifestation of dyslexia across orthographies. Differences in lexical representations and reading across languages leave developmental "footprints" in the adult lexicon. The lexical organization and processing strategies that are characteristic of skilled reading in different orthographies are affected by different developmental constraints in different writing systems. The authors develop a novel theoretical framework to explain these cross-language data, which they label a psycholinguistic grain size theory of reading and its development.     

Phonology, reading acquisition, and dyslexia: insights from connectionist models.

The development of reading skill and bases of developmental dyslexia were explored using connectionist models. Four issues were examined: the acquisition of phonological knowledge prior to reading, how this knowledge facilitates learning to read, phonological and nonphonological bases of dyslexia, and effects of literacy on phonological representation. Compared with simple feedforward networks, representing phonological knowledge in an attractor network yielded improved learning and generalization. Phonological and surface forms of developmental dyslexia, which are usually attributed to impairments in distinct lexical and nonlexical processing "routes," were derived from different types of damage to the network. The results provide a computationally explicit account of many aspects of reading acquisition using connectionist principles.     

The extended argument dependency model: a neurocognitive approach to sentence comprehension across languages

Real-time language comprehension is a principal cognitive ability and thereby relates to central properties of the human cognitive architecture. Yet how do the presumably universal cognitive and neural substrates of language processing relate to the astounding diversity of human languages (over 5,000)? The authors present a neurocognitive model of online comprehension, the extended argument dependency model (eADM), that accounts for cross-linguistic unity and diversity in the processing of core constituents (verbs and arguments). The eADM postulates that core constituent processing proceeds in three hierarchically organized phases: (1) constituent structure building without relational interpretation, (2) argument role assignment via a restricted set of cross-linguistically motivated information types (e.g., case, animacy), and (3) completion of argument interpretation using information from further domains (e.g., discourse context, plausibility). This basic architecture is assumed to be universal, with cross-linguistic variation deriving primarily from the information types applied in Phase 2 of comprehension. This conception can derive the appearance of similar neurophysiological and neuroanatomical processing correlates in seemingly disparate structures in different languages and, conversely, of cross-linguistic differences in the processing of similar sentence structures.     

Functional neuroimaging studies of reading and reading disability (developmental dyslexia)

Converging evidence from a number of neuroimaging studies, including our own, suggest that fluent word identification in reading is related to the functional integrity of two consolidated left hemisphere (LH) posterior systems: a dorsal (temporo-parietal) circuit and a ventral (occipito-temporal) circuit. This posterior system is functionally disrupted in developmental dyslexia. Reading disabled readers, relative to nonimpaired readers, demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers the dorsal circuit predominates at first, and is associated with analytic processing necessary for learning to integrate orthographic features with phonological and lexical-semantic features of printed words. The ventral circuit constitutes a fast, late-developing, word identification system which underlies fluent word recognition in skilled readers.     

Phonetic awareness and reading acquisition

Summary Three issues are dealt with: the relationship between phonetic awareness and reading acquisition, the nature of the cognitive capacities that make phonetic awareness possible, and the potential influence of phonetic awareness on language perception and comprehension. Data on the relationships between phonetic awareness and reading acquisition support an interactive view. For most people, learning to read in the alphabetic system stimulates phonetic awareness. On the other hand, phonetic awareness is a critical factor for success in reading acquisition. Indications about the nature of the cognitive capacities that underlie phonetic awareness may be obtained by inspecting its development. Two capacities at least seem to be required: the capacity to ignore meaning and focus on the sound properties of speech and the capacity of segmentation.Lack of phonetic awareness does not imply that phonetic processing does not take place during speech perception. Recent data suggest that speech perception includes a stage of extraction of phonetic features regardless of whether or not the subject is able to segment speech into phones explicitly. However, phonetic awareness may influence perceptual strategies and the relative weight of meaning expectancies in identification.Our work received support from the Belgian Fonds de la Recherche fondamentale collective (F.R.F.C.) under contracts No. 2.4505.76 and 2.4505.80 as well as from the Belgian Ministère de la Politique et de la Programmation scientifiques (Action de Recherche concertée Processus cognitifs dans la lecture)     

Surface dyslexia: A case report and some theoretical implications to reading models

This paper reports on the psycholinguistic investigation of a surface dyslexic aphasic patient's abilities to handle written material. The analysis of paralexic errors produced in reading aloud single words and nonwords classically suggested that the patient was using an analytical strategy parsing the letter string stimulus, from left to right, into graphemes, and assigning phonemic values to graphemes. The patient's results were found to be sensitive to irregularities in correspondence between graphemes and phonemes not only in reading aloud but in lexical decisions, writing on dictation, rhyming, and written-word comprehension. Moreover, the patient's linguistic behavior brought out the reverse pattern observed in deep-dyslexic performances within word/nonword and content/function word dimensions. It was found that some semantic information about written words could be retrieved from both phonological and nonphonological processes presumably operating concurrently and both providing converging or conflicting pieces of meaning to the understanding of written words. Some considerations derived from the observation of this pathological reading behavior are discussed, contributing to a psycholinguistic model of normal reading.     

Right-hemisphere reading in a case of developmental deep dyslexia

The right-hemisphere hypothesis of deep dyslexia has received support from functional imaging studies of acquired deep dyslexia following damage to the left cerebral hemisphere, but no imaging studies of cases of developmental deep dyslexia, in which brain damage is not suspected, have been reported. In this paper, we report the first evidence of right hyperactivation in an adult case of developmental deep dyslexia. Hyperactivation was observed in the right inferior frontal cortex during functional magnetic resonance imaging (fMRI) of the oral reading of imageable content words and nonwords to which imageable lexical responses were frequently made. No evidence of right hyperactivation was observed in the oral reading of function words, nor during the naming of imageable words in response to pictured objects. The results reveal strategic and selective use of right-hemisphere functions for particular types of written stimuli. We propose that children with developmental deep dyslexia compensate for their lack of phonological skills by accessing right-hemisphere imageable associations that provide a mnemonic for linking written forms to spoken names.     

Right-hemisphere reading in a case of developmental deep dyslexia

The right-hemisphere hypothesis of deep dyslexia has received support from functional imaging studies of acquired deep dyslexia following damage to the left cerebral hemisphere, but no imaging studies of cases of developmental deep dyslexia, in which brain damage is not suspected, have been reported. In this paper, we report the first evidence of right hyperactivation in an adult case of developmental deep dyslexia. Hyperactivation was observed in the right inferior frontal cortex during functional magnetic resonance imaging (fMRI) of the oral reading of imageable content words and nonwords to which imageable lexical responses were frequently made. No evidence of right hyperactivation was observed in the oral reading of function words, nor during the naming of imageable words in response to pictured objects. The results reveal strategic and selective use of right-hemisphere functions for particular types of written stimuli. We propose that children with developmental deep dyslexia compensate for their lack of phonological skills by accessing right-hemisphere imageable associations that provide a mnemonic for linking written forms to spoken names.     

Word association and the acquisition of reading

Two studies relating reading ability to word association responses were carried out. The first involved early readers and matched control children from pre-first-grade classes. There were 29 early readers and 29 nonreading controls matched for age, sex, and IQ. The early readers were found to give significantly more paradigmatic, or same-form-class, responses than the controls. The second study related reading ability, mental age, and word association responses in developmentally delayed teen-agers and young adults, and pre-first-grade children who varied in reading ability. With partial correlation reading ability was found to be related to paradigmatic responding, while mental age was not significantly related. These results indicate that reading acquisition may change word association responses in children through a reorganizing process in the lexicon.The authors would like to thank the Halifax and Dartmouth School Boards for their cooperation. We would also like to thank Paul Cable of Special Education, and the principals and teachers: Beth Conrad, Karen Duerdan, Elaine Fram, Peter Montgomery, Wayne Serebrin, and Bill Schipilow. Their help was greatly appreciated. An earlier version of study 1 was presented at the American Psychological Association meeting in Los Angeles, August 1981.     

Word length effect in early reading and in developmental dyslexia

Vocal reaction times were measured in Italian dyslexics and in proficient readers while they read single words. Three groups of control participants (for a total of 79) were tested. All were in the first, second or third grade of elementary school. Nine third graders with a low level of reading ability when assessed by standard reading procedures were also tested. Results indicated that vocal RTs of control participants were faster and less sensitive to word length as a function of age; also, there was a particularly marked change between first and second graders. Dyslexics' vocal RTs and errors were much worse than those of peer control participants and resembled those of first grade controls. It is suggested that normal readers in an orthographically transparent language (Italian) adopt a lexical strategy quite early in their learning. On the contrary, dyslexics seem unable to learn this mode of processing and continue to use a sub-lexical reading procedure.     

Developmental dyslexia and widespread activation across the cerebellar hemispheres

Developmental dyslexia is the most common learning disability in school-aged children with an estimated incidence of five to ten percent. The cause and pathophysiological substrate of this developmental disorder is unclear. Recently, a possible involvement of the cerebellum in the pathogenesis of dyslexia has been postulated. In this study, 15 dyslexic children and 7 age-matched control subjects were investigated by means of functional neuroimaging (fMRI) using a noun-verb association paradigm. Comparison of activation patterns between dyslexic and control subjects revealed distinct and significant differences in cerebral and cerebellar activation. Control subjects showed bilaterally well-defined and focal activation patterns in the frontal and parietal lobes and the posterior regions of the cerebellar hemispheres. The dyslexic children, however, presented widespread and diffuse activations on the cerebral and cerebellar level. Cerebral activations were found in frontal, parietal, temporal and occipital regions. Activations in the cerebellum were found predominantly in the cerebellar cortex, including Crus I, Crus II, hemispheric lobule VI, VII and vermal lobules I, II, III, IV and VII. This preliminary study is the first to reveal a significant difference in cerebellar functioning between dyslexic children and controls during a semantic association task. As a result, we propose a new hypothesis regarding the pathophysiological mechanisms of developmental dyslexia. Given the sites of activation in the cerebellum in the dyslexic group, a defect of the intra-cerebellar distribution of activity is suspected, suggesting a disorder of the processing or transfer of information within the cerebellar cortex.     

Investigating the boundaries of reading units across ages and reading levels

In Experiments 1 and 2 first-, third-, and seventh-grade children and college subjects circled the letter a while reading passages constructed of words familiar to first graders. First graders made more errors on the letter a embedded in a word than on the word a, whereas the converse was true of the other age groups. In Experiments 3 and 4 first-, second-, fourth-, and seventh-grade children and college students read passages and circled the letter t, making more errors on the common word the than on other words and on correctly spelled than on misspelled words. The effect of misspelling the other words increased with age and reading skill. Our combined results suggest that reading unit size increases with age and reading ability and that, whereas younger children, like adults, unitize common words, the unitization of less common words increases as word configurations become more familiar.     

Early precursors and enabling skills of reading acquisition

Research on early linguistic precursors and enabling skills of reading acquisition among young children is reviewed. Language development starts early in infancy when the child learns to categorize the speech sounds according to the pattern typical of the mother tongue. Equipped with these sound categories the child is ready to learn to segment words from the sound stream and to understand and to use words. The precise phonological representation of words will facilitate the important development of phonological awareness, a basic prerequisite for reading acquisition. This paper reviews some of my longitudinal research and training studies indicating the causal direction of the relation between phonological awareness and reading and includes some ongoing studies, where gender differences, socio‐economic factors, dose‐response‐effects and motivational factors are explored. Preventive and remedial implications of the findings are pointed out. Finally, the complexity of the causal relationships between different aspects of early language development, including genetic influences and later reading is pointed out.     

The timing deficit hypothesis of dyslexia and its implications for Hebrew reading

Vast amounts of neuropsychological evidence have been collected in recent years in support of the hypothesis that developmental dyslexia is caused not only by phonological deficits, but also by timing deficits that affect all senses (e.g., Tallal, Miller, & Fitch, 1995; Stein & Walsh, 1997). In parallel, recent developments in the study of Hebrew reading place heavy emphasis on root awareness in the mental lexicon and early root extraction in the process of word identification (e.g., Frost, Forster, & Deutch, 1997). The present study creates a link between the timing hypothesis and the special demands of Hebrew reading. The performance of dyslexics and normally reading children is compared on tasks requiring visual extraction of trigrams that approximates extracting roots out of Hebrew words. Partial findings show that dyslexics take longer and make more errors while performing trigram extractions on all levels examined, and that sequentiality in the task affects dyslexics and skilled readers in different ways.     

Methodological considerations in performing semantic- and translation-priming experiments across languages

Research in the field of bilingualism has had as its principal aim to describe the structure and function of memory for bilingual speakers. A primary technique that has been used to examine bilingual memory is an examination of cross-language word priming (semantic and translation), using the lexical decision and pronunciation tasks. Although studies have, on occasion, revealed greater degrees of word priming from a dominant to a subordinate language, in comparison with the reverse, a careful review of the methodology that has been used reveals a number of issues that render conclusions such as this quite problematic. Parameters of concern include language proficiency, cognate status, masking, control conditions, word frequency and length, stimulus onset asynchrony, relatedness proportion, and nonword ratio. These factors are discussed, as well as recommendations for conducting future empirical research in this area of investigation.