Remediating the core deficits of developmental reading disability: a double-deficit perspective

The double-deficit hypothesis (Wolf, 1997; Wolf & Bowers, 1999, this issue) contends that deficits in phonological awareness and deficits in visual naming speed represent two independent causal impediments to reading acquisition for children with developmental reading disabilities (RD). One hundred and sixty-six children with severe RD from 7 to 13 years of age were classified into three deficit subgroups according to a double-deficit framework. A total of 140 children with RD, 84% of the sample, were classified; 54% demonstrated a double deficit (DD), 22% a phonological deficit only (PHON), and 24% a visual-naming speed deficit only (VNS). Diagnostic test profiles highlighted the joint contributions of the two core deficits in depressing written language acquisition. The children in the DD group were more globally impaired than those in the other subgroups, and the VNS group children were the highest achieving and most selectively impaired readers. Following 35 hours of word identification training, sizable gains and significant generalization of training effects were achieved by all subgroups. A metacognitive phonics program resulted in greater generalized effects across the domain of real English words, and a phonological training program produced superior outcomes within the phonological processing domain. The greatest non-word reading gains were achieved by children with only phonological deficits.     

The varieties of pathways to dysfluent reading: comparing subtypes of children with dyslexia at letter, word, and connected text levels of reading

The majority of work on the double-deficit hypothesis (DDH) of dyslexia has been done at the letter and word levels of reading. Key research questions addressed in this study are (a) do readers with different subtypes of dyslexia display differences in fluency at particular reading levels (e.g., letter, word, and connected text)? and (b) do children with dyslexia identified by either low-achievement or ability-achievement discrepancy criteria show similar differences when classified by the DDH? To address these questions, the authors assessed a sample of 158 children with severe reading impairments in second and third grades on an extensive battery and classified them into three reader subtypes using the DDH. The results demonstrated that the three DDH subtypes exhibited differences in fluency at different levels of reading (letter, word, and connected text), underscoring the separate reading profiles of these subtypes and the different possible routes to dysfluency in reading disabilities. Furthermore, the results suggest that the different patterns among DDH subtypes are primarily driven by the ability-achievement discrepancy group. The implications of these findings are discussed for intervention, reading theory, and a more refined understanding of heterogeneity.     

Evaluation of the double-deficit hypothesis subtype classification of readers in Spanish

The double-deficit hypothesis acknowledges both phonological processing deficits and serial naming speed deficits as two dimensions associated with reading disabilities. The purpose of this study was to examine these two dimensions of reading as they were related to the reading skills of 29 Spanish average readers and poor readers (mean age 9 years 7 months) who met the criteria for either single phonological deficit (PD), double deficit (DD), or no deficit. DD children were the slowest readers and had the weakest orthography processing skills. No significant differences were found between PD and DD groups on word and pseudoword reading. Word reading and reading comprehension skills were average or above average in the three studied groups. As in previous studies in transparent orthographies, word reading was not a salient problem for Spanish poor readers, whereas for the DD group, reading speed and orthographic recognition skills were significantly affected.     

Follow-up of children with early expressive phonology disorders

Fifty-two children identified at age 4 to 6 years as demonstrating a moderate to severe expressive phonology disorder were followed to the third and fourth grades. Children were classified into two groups based on the presence of an early phonology disorder in isolation (P) or the presence of a phonology disorder with other language problems (PL). At follow-up, articulation measures failed to differentiate the groups; however, the PL group performed more poorly than the P group on measures of phoneme awareness, language, reading decoding, reading comprehension, and spelling. The P group demonstrated poor spelling skills relative to their reading and language abilities, suggesting residual spelling weaknesses in these children. The PL group reported more nuclear family members with speech-language disorders and with reading disorders than the P group. Findings support previous research linking early language disorders with later reading difficulties.     

Executive functions in elementary school children with and without problems in written expression

This study examined the executive functioning of 55 elementary school children with and without problems in written expression. Two groups reflecting children with and without significant writing problems were defined by an average primary trait rating across two separate narratives. The groups did not differ in terms of chronological age, ethnicity, gender, socioeconomic status, special education status, or presence of attention problems or receptive vocabulary capabilities; however, they did differ in reading decoding ability, and this variable was controlled for in all analyses. Dependent measures included tasks tapping an array of executive functions grouped conceptually in accordance with a model of executive functioning reflecting the following domains: initiate, sustain, set shifting, and inhibition/stopping. Analysis of covariance (ANCOVA) procedures revealed statistically significant group differences on the initiation and set shift domains, with the sustaining domain approaching significance. Children with writing problems performed more poorly in each of these domains, although the effect sizes were small. A multiple regression that employed these four factors and the reading decoding variable to predict the primary trait score from the written narratives revealed a statistically significant regression function; however, reading decoding contributed most of the unique variance to the writing outcome. These findings point out the importance of executive functions in the written language process for elementary school students, but highlight the need to examine other variables when studying elementary school-age children with written expression problems.     

Naming speed deficits in adults with reading disabilities: a test of the double-deficit hypothesis

The present study investigated the persistent nature of naming speed deficits within the context of the double-deficit hypothesis in a university sample of adults with reading disabilities (RD). Twenty-five university students with RD were compared to 28 typically achieving readers on measures of reading skill, phonological processing, and naming speed. The results indicated that both naming speed and phonological processing deficits characterized the RD group. In a regression analysis, neither naming speed nor phonological processing were important variables in explaining comprehension when reading rate was in the model. The results of the present study are mixed at best and are consistent with earlier conclusions that support for the double-deficit hypothesis of dyslexia remains limited.     

Language Basis of Reading and Reading Disabilities: Evidence From a Longitudinal Investigation

This study examined the contributions of phonological processing and oral language abilities to reading and reading disabilities in young children. Two approaches were taken. First, 604 participants were divided into good and poor readers on the basis of reading performance in second grade. Reading groups were then compared in terms of kindergarten phonological processing and other language abilities. In a second approach, multiple regression was employed to investigate the relative contributions of phonological processing and oral language abilities in predicting second-grade reading achievement across reading groups. Results indicated that over 70% of poor readers had a history of language deficits in kindergarten. Most of these children had problems in both phonological processing and oral language. Regression analyses further indicated that oral language and phonological processing abilities each accounted for unique variance in reading achievement. These results suggest that language-based theories of reading and reading disabilities must include both phonological processing and oral language abilities.     

Phonological processing deficits in specific reading disability and specific language impairment: same or different?

The aim of this study was to determine if phonological processing deficits in specific reading disability (SRD) and specific language impairment (SLI) are the same or different. In four separate analyses, a different combination of reading and spoken language measures was used to divide 73 children into three subgroups: poor readers with average spoken language (SRD), poor readers with poor spoken language (SRD + SLI) and average readers with poor spoken language (SLI). These groups were compared on five phonological processing measures. The SRD group had deficits in neural representations of phonemes, phoneme discrimination, phoneme awareness and rapid naming. The SRD + SLI group had more severe deficits than the SRD group on half of these measures, as well as phonological short‐term memory. Children with SLI were free from phonological processing deficits. Thus, phonological processing deficits were the same or different in SRD and SLI, depending on how SRD and SLI were defined, and how phonological processing was measured.     

An evaluation of the discrepancy definition of dyslexia.

The purpose of this study was to determine whether children with dyslexia, that is, children whose reading levels were significantly lower than would be predicted by their IQ scores, constituted a distinctive group when compared with poor readers, that is, children whose reading scores were consistent with their IQ scores. The performance of children with dyslexia, poor readers, and normally achieving readers was compared on a variety of reading, spelling, phonological processing, language, and memory tasks. Although the children with dyslexia had significantly higher IQ scores than the poor readers, these two groups did not differ in their performance on reading, spelling, phonological processing, or most of the language and memory tasks. In all cases, the performance of both reading disabled groups was significantly below that of nondisabled readers. The findings were similar whether absolute difference or regression scores were used. Reading disabled children, whether or not their reading is significantly below the level predicted by their IQ scores, experience significant problems in phonological processing, short-term and working memory, and syntactic awareness. On the basis of these data, there does not seem to be a need to differentiate between individuals with dyslexia and poor readers. Both of these groups are reading disabled and have deficits in phonological processing, verbal memory, and syntactic awareness.     

Comparing the effects of different book reading techniques on young children’s language development

The purpose of this research study is to compare the effects of digital, dialogic and traditional reading on children’s language development aged 48–66 months. Fifty-six randomly selected children enrolled in three different classrooms in a public preschool in Turkey participated in the study. The three classrooms were again randomly assigned as digital, dialogic and traditional reading groups. During the reading activities, a total of 24 storybooks were read by each group every three times in 8 weeks. While the children’s language scores (the receptive and expressive language scores) resulted in a significant increase in dialogic reading, the children’s language scores in a digital and traditional reading group slightly changed during the intervention. Alternatively, qualitative data suggested that the interaction between teacher and children and between children and children were very limited in a digital and traditional reading group and that limited interaction during reading was the underlying cause of the insignificant increase in children’s language scores.

     

A Four Year Follow‐up Study of Low Socioeconomic Status,Latin American Children with Reading Difficulties

This paper presents the results of a follow‐up study of reading difficulties among Spanish‐speaking Latin American children of low socioeconomic background (SES) over four school years. The research started with a group of 93 children with reading difficulties (RD) by 2nd and 3rd grade teachers in four schools and a control group of 63 children without reading difficulties (ND), belonging to the same schools. Both groups were equivalent in age, grade, gender and SES. All children were tested on reading decoding and comprehension, reading and writing pseudo‐words, verbal abilities, visual perception, phonological processing, and the WISC‐R. Neither SES nor IQ accounted significantly for the reading difficulties in the RD group. The most predictive variables of the final reading level in the RD group were phonological processing, verbal abilities, and the initial level of decoding. After four years, 17% of the initial RD children had reached an average level of reading, but 11% of this group remained with severe reading difficulties and may be considered as dyslexic children. The RD children who became average readers were not significantly different from the control group in verbal abilities, nor in phonological processing. Nevertheless, they were significantly different in terms of IQ scores. The neuropsychological characteristics of the children with severe reading difficulties appear similar to those found in children with dyslexia in more developed countries.     

Reading and spelling among nonvocal children with cerebral palsy: Influence of home and school literacy environment

In literacy research, home literacy experiences and exposure to print have been ascribed a contributing role in later reading development along with metalinguistic and other cognitive skills. In a study on reading and spelling skills in nonvocal children the home and school literacy experiences of 35 children with cerebral palsy were studied by means of questionnaires. The questionnaires were completed by the parents and teachers. The answers from the disability group were compared with the answers from two comparison groups, one matched for mental age and sex and the other for sex and IQ. The results revealed few differences in the home literacy experiences of the three groups. The children of all three groups had access to a variety of printed materials, and there were no differences in the parents' reading habits or in their values and high priority given to literacy. The disabled children took a passive role in story reading with little linguistic interaction, and the parents took the active part. The results indicated that home literacy experiences in the groups studied at best had a marginal influence on reading development. Individual differences in speech and language abilities were proposed to have higher explanatory value of the low literacy skills found among nonvocal children.     

Testing the double-deficit hypothesis in an adult sample

The double-deficit hypothesis of dyslexia posits that reading deficits are more severe in individuals with weaknesses in phonological awareness and rapid naming than in individuals with deficits in only one of these reading composite skills. In this study, the hypothesis was tested in an adult sample as a model of reading achievement. Participants were parents of children referred for evaluation of reading difficulties. Approximately half of all participants reported difficulty learning to read in childhood and a small subset demonstrated ongoing weaknesses in reading. Structural equation modeling results suggest that the double-deficit hypothesis is an accurate model for understanding adult reading achievement. Better reading achievement was associated with better phonological awareness and faster rapid automatized naming in adults. Posthoc analyses indicated that individuals with double deficits had significantly lower reading achievement than individuals with single deficits or no deficits.     

The utility of Chinese tone processing skill in detecting children with English reading disabilities

The utility of Chinese tone processing skill in detecting children with English reading difficulties was examined through differences in a Chinese tone experimental task between a group of native English‐speaking children with reading disabilities (RD) and a comparison group of children with normal reading development (NRD). General auditory processing, English phonemic processing and English reading skills were also tested. We found differences between groups in Chinese tone processing skill, as well as general auditory processing and English phonemic skills. The RD group was significantly poorer than NRD on tasks of Chinese tone, phonemic and frequency modulated (FM) tone processing. Another finding was a different pattern of relationship between RD and NRD groups in Chinese tone, phonemic and FM tone processing as predictors of reading skills. For children with RD, FM tone processing was a significant predictor of pseudoword reading; for NRD, phonemic and Chinese tone processing skills predicted real word reading. These findings contribute to improved understanding of the roles of general auditory processing and phonological processing skills in RD, with implications for assessment and intervention with children who have English reading difficulties.     

Reading comprehension,working memory and higher-level language skills in children with SLI and/or dyslexia

This study examined (1) whether working memory and higher-level languages skills—inferencing and comprehension monitoring—accounted for individual differences among Chinese children in Chinese reading comprehension, after controlling for age, Chinese word reading and oral language skills, and (2) whether children with specific language impairment (SLI) or dyslexia showed deficits in these skills. Eighty-two Cantonese Chinese-speaking children between the age of 7; 8–9; 5 were assessed. Regression analyses on the full sample offered support for the first question. The children were also classified into four groups: Typically-developing (TD; N = 34), specific language impairment-only (SLI-only; N = 18), SLI-dyslexia comorbid (SLI-D; N = 22) and dyslexia-only (D-only; N = 8). Pair-wise comparisons focusing on the second question revealed that both the SLI-only and the D-only group performed worse than the TD group in reading comprehension after controlling for age and nonverbal intelligence. The SLI-only and the D-only group showed a different profile of deficits: only the SLI-only group performed worse than the TD group in working memory, comprehension monitoring, and inferencing. The SLI-D comorbid group did worse than the SLI-only, but not the D-only group, in reading comprehension. The SLI-D comorbid group did not do worse than either single diagnosis group in the higher-level language skills associated with reading comprehension. These findings suggested adopting different intervention approaches for reading comprehension difficulties in children with SLI versus children with dyslexia.     

Persistent arithmetic, reading, or arithmetic and reading disability

The achievement of 1,075 school children was followed to the end of grade 7 or 8. Retrospective details of birth, medical history, and infant adaptive behavior, as well as current information about preschool behavior, were provided by parents before kindergarten entry when their children were ages four to five. At that time, each child was given language, preacademic, and visual-motor tests, and a short-form verbal IQ was obtained. For grades 1 to 8, a mean 6.9 percent qualified as low in arithmetic (including 3.9 percent low only in arithmetic) and 9 percent as low in reading (including 6 percent low only in reading). Groups of children with persistent disability in arithmetic only (2.3 percent), reading only (6.6 percent), and arithmetic plus reading (3.4 percent) were compared on all variables, and gender differences were examined. The specific arithmetic group was superior to the other two groups in preschool verbal IQ and language, and had suffered more birth problems and illness. As found by Rourke and his colleagues (e.g., Rourke and Finlayson 1978) for older children, boys with a specific arithmetic disability showed a preschool profile with high verbal scores and low nonverbal scores. Many gender differences were found for the total sample, but few for the learning disability subgroups.     

A developmental perspective on dyslexic subtypes

In this paper we apply a developmental model of reading to the question of dyslexic subtypes. Groups of normal readers (n=40) and dyslexic children (n=50), matched on reading level and IQ, were given a comprehensive test battery measuring level of development of visual, phonological, and orthographic skills. As a group, dyslexics deviated from normal readers of equivalent reading achievement primarily in phonological skills (spelling-to-sound translation and phonemic analysis), although limited differences in knowledge of word-specific spellings were also observed. Dyslexics were superior to the younger normal readers in visual processing of print. Analysis of individual data by reference to the reading level control group revealed three major subgroups: a group with a specific deficit in phonological processing of print (52 percent), a group with deficits in processing both the phonological and orthographic features of printed words (24 percent), and a group with phonological deficits in language (8 percent). The remainder of the sample (16 percent) had specific deficits in visual or orthographic processing of print, in spelling, or did not differ from the control group. The data support the view that most developmental dyslexics have a specific language disorder involving some aspect of phonological processing. However, small subgroups with very different configurations of reading and nonreading difficulties may exist as well. This research was supported by an NICHD grant to the first author (USPHS grant 1 R23 HD20231).     

Investigating Cognitive and Linguistic Abilities that Influence the Reading Comprehension Skills of Children from Diverse Linguistic Backgrounds

This study investigated the influence of cognitive and linguistic skills on the reading comprehension performance of a group of learners from diverse linguistic backgrounds. The study also compared the reading comprehension performance of grade 4 children who entered kindergarten with little or no experience with English (ESL) to that of a group of native English speakers. Examiners administered various tasks of reading, language, and memory to the children in the study (n=480). The sample included three comprehension groups: (1) children with poor comprehension in the absence of word reading difficulties (Poor Comprehenders; PC), (2) children with poor word reading and poor comprehension (Poor word Recognition and comprehenders; PR), and (3) children with good word reading and comprehension abilities (Good Comprehenders; GC). Due to the small sample size of PR reader group, no comparative analyses were conducted. However, the results indicated that within the GC and PC groups there were no differences between the ESL and L1 children on measures of reading and phonological processing. Further, within the GC and PC groups, on measures of syntactic awareness and verbal working memory, the ESL speakers performed at significantly lower levels than the L1 speakers.     

The Double-Deficit Theory of Reading Disability Does Not Fit All

The double-deficit theory of reading disability (Wolf & Bowers, 1999) was examined in a sample of 56 reading-disabled and 45 normal-reading elementary school children (aged 8 to 11). As hypothesized, the two groups differed markedly on all phonological analysis tasks and on rapid continuous naming of digits and letters (the double deficits), but they differed as well on orthographic tasks, attention ratings, arithmetic achievement, and all WISC-III factors except perceptual organization. Within the reading-disabled (RD) sample, children in the double-deficit subgroup were no more impaired in reading and spelling than those with a single deficit in phonological analysis, and those with a single deficit in rapid naming were no more impaired than those with neither deficit. Multiple regression analyses suggest that a multiple causality theory of RD is more plausible than a double-deficit theory.     

Latent profile analysis of students’ reading development and the relation of cognitive variables to reading profiles

Previous studies have showed that early problems with word decoding can lead to poor performance in text reading and comprehension and suggest that poor readers often struggle with reading deficits throughout their school years. Therefore, early detection of those children who are at risk for slow reading development and/or who belong to the lowest reading profiles is essential in order to organize proper support. The present study explores the heterogeneity and prevalence of latent reading profiles among 769 Finnish- and German-reading students during their first and second school years in three countries (Finland, Germany, and Italy) using latent profile analysis. The results identified three latent profiles among Finnish readers, one of which (sentence-level reading) was identified as developing slowly. Among German-reading students, four latent profiles were discovered, two of which were identified as developing slowly. The results of ordinal logistic regression modeling show that rapid automatic naming (RAN) was significantly related to poorer reading profiles among Finnish- and German-reading students, and that the poorer results in letter-sound connection testing among the German-reading group was also significantly related to poorer reading profiles. Although the educational systems have some differences between Germany and German-speaking areas of Italy, no significant country effect was detected. In addition, a child’s age and spoken language did not significantly affect the student’s reading profile.