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).     

Electrophysiological correlates of infant recognition memory

Event-Related Potentials were recorded from 6-month-old infants in order to examine the electrophysiological correlates of recognition memory. In 1 study, infants were shown 1 face briefly, followed by the same face presented with high probability, and a novel face presented with low probability. 2 components were observed that distinguished between the novel and familiar events. Differences between these components in latency, polarity, and scalp topography led to the suggestion that 2 processes were involved in recognizing the stimuli. In a second study infants were again presented with 1 face briefly, followed by the same face and a novel face presented with equal probability. 1 component at central scalp distinguished between the novel and familiar events. In a third study, infants were simply presented with 2 previously unseen faces equally often. Infants responded as if the faces were identical, suggesting that previous experience with 1 stimulus directs infants' attention to the novel stimulus during the test portion of the task. The extent to which the observed responses reflect the updating of working memory is discussed, as is the extent to which infants' electrophysiological response to stimulus novelty and uncertainty resembles the adult's.     

The boder test: Neuropsychological and demographic features of dyslexic subtypes

The Boder Test may represent a viable screening instrument for the identification of dyslexia and dyslexic subtypes. Proportions of the 30 LD children studied identified by Boder's classification system as dysphonetic (63.3%), dyseidetic (6.7%), and mixed dysphonetic-dyseidetic (13.3%) were similar to those reported in earlier studies. Neuropsychological characteristics associated with the Boder categories were consistent with the literature: Significantly fewer dysphonetic readers were represented in the V > and Spatial<Sequential IQ groups, and left-handedness and left-hand tapping preference were overrepresented in the mixed dyslexic category. Black children who had been identified as learning disabled on the basis of other tests were categorized as normal readers by the Boder, suggesting its possible use as a nonbiased measure of reading.     

Rorschach responses of dyslexic children

Fifteen dyslexic children between the ages of 8 and 16 were given the Rorschach ink blot test and their responses were compared with those of 12 suitably matched controls. It was found that they made very considerable use of the shape of the cards, but much less use of the other determinants (color, texture, etc.). Unlike the controls they seldom turned the cards around so as to obtain some fresh “view,” and the overall number of responses per person was considerably less, with many of them giving only one response per card. It is suggested that the educational and social pressures on a dyslexic child often make him reluctant to commit himself in a context where “playing safe” is socially acceptable.     

Development of dyslexic subgroups:

There is a consensus that dyslexia is on a continuum with normal reading skill and that dyslexics fall at the low end of the normal range in phonological skills. However, there is still substantial variability in phonological skill among dyslexic children. Recent studies have focused on the high end of the continuum of phonological skills in dyslexics, identifying a “surface” dyslexic, or “delayed” profile in which phonological skills are not out of line with other aspects of word recognition. The present study extended this work to a longitudinal context, and explored differences among subgroups of dyslexics on a battery of component reading skills. Third grade dyslexics (n=72) were classified into two subgroups, phonological dyslexics and delayed dyslexics, based on comparisons to younger normal readers at the same reading level (RL group). The children were tested at two points (in third and fourth grade). The results revealed that the classification of dyslexics produced reliable, stable, and valid groups. About 82 percent of the children remained in the same subgroup category when retested a year later. Phonological dyslexics were lower in phoneme awareness and expressive language. Delayed dyslexics tended to be slower at processing printed letters and words but not at rapid automatic naming of letters, and relied more heavily on phonological recoding in reading for meaning than did phonological dyslexics. A subset of the delayed dyslexics with the traditional “surface dyslexic” pattern (relatively high pseudoword and low exception word reading) was also identified. The surface subgroup resembled the RL group on most measures and was not very stable over one year. The results are discussed in light of current models of dyslexia and recent subgrouping schemes, including the Double-Deficit Hypothesis.     

Letter processing in dyslexic subgroups

Hypothesized cognitive strengths and weaknesses of three dyslexic subgroups (Boder and Jarrico 1982) were examined in two reading related experiments. The first experiment tested the prediction that auditorily presented letter sets should be processed better by dyseidetic than by dysphonetic readers. The prediction was not confirmed. The results did not show any modality of presentation-specific recall differences between the three dyslexic subgroups. Overall, dyslexic children’s scores were significantly lower than those of age-matched control groups. The second experiment tested predictions of differential performance of dyseidetic and dysphonetic readers in a task in which the name identity of letters in pairs had to be indicated. Predicted patterns were not confirmed. Compared to the control groups all three dyslexic subgroups (whose means did not differ significantly) made significantly more errors in the condition in which it was essential to activate phonetic representations of the letters. The experimental results of this study suggest a greater similarity in the nature of letter processing problems in dyslexic children than is assumed in Boder and Jarrico’s (1982) subtyping test. This research was supported by grant 634301 from the Department of Special Education, State University of Groningen, and a travel grant from the Netherlands Organization for the Advancement of Pure Research (Z.W.O.). Based on a presentation at the 32nd Annual Conference of The Orton Dyslexia Society, Baltimore, Maryland, November 1982.     

A follow-up study of dyslexic boys

Over 500 men who attended the Gow School, an independent school for boys with developmental dyslexia, were given a follow-up questionnaire from 1 to 38 years after they left the school. More than half had graduated from college; business was the most frequently chosen major in college; most were employed in managerial or related business positions; and their adult reading habits and attitudes did not compare well with those of other men of similar socioeconomic backgrounds. Socioeconomic status and IQ were not predictive of adult outcome among these men in contrast to their effect in the general population. An important result was that severity of the reading problem upon entrance to Gow and the academic and remedial progress of the men while at the school were highly predictive of adult educational, occupational, and attitudinal status. This work was supported by funds from NIH grant HD00486, the Gow School, and the John F. Kennedy Institute.     

Early syntactic development of dyslexic children

The syntactic development of preschoolers who later became disabled readers was compared to that of children who were similar to the dyslexics in sex, socioeconomic status, and IQ, but who became normal readers. Expressive and receptive syntactic abilities were examined longitudinally from age 30 to 60 months. The dyslexic group was poorer than the control group on all measures until the age of five, at which time both groups exhibited similar syntactic proficiency. The etiological relation of language development to reading disabilities is discussed. This research was supported by grants from the National Institute of Child Health and Human Development and the March of Dimes Birth Defects Foundation.     

Orthographic learning in dyslexic Spanish children

Reading fluency is one of the basic processes of learning to read. Children begin to develop fluency when they are able to form orthographic representations of words, which provide direct, smooth, and fast reading. Dyslexic children of transparent orthographic systems are mainly characterized by poor reading fluency (Cuetos & Suárez-Coalla 2009; Spinelli, De Luca, Di Filippo, Mancini, Martelli, & Zoccolotti, 2005; Wimmer, 1993). Therefore, the main problem for these children could be the difficulty in developing orthographic representations of the words they read. The aim of this study was to test the ability of dyslexic Spanish-speaking children (whose native language is Spanish) to develop orthographic representations and determine if the context helps them. For this, two experiments were conducted with a group of 100 children, 7–12 years of age. The groups were comprised of 20 dyslexics, 40 chronological age-matched controls and 40 reading level-matched controls. In the first experiment, eight unfamiliar words (four short and four long) were presented six times within the context of a story. In the second experiment, eight pseudowords were presented on a computer and the children had to read them aloud. In both experiments, the reading and articulation times of experimental and control stimuli were compared, before and after the training. Children without dyslexia showed a decrease of the influence of length of word on reading speed, indicating a lexical reading, while for dyslexic children, the influence of length remained unchanged. These results appeared when the stimuli were presented in the context of a story as well as when presented in isolation. In short, our results describe that dyslexic children of transparent orthographic systems have problems in developing orthographic representations of words.     

Linguistic profiles of dyslexic and good readers

Linguistic profiles of 60 boys with average intelligence were examined at kindergarten, grade 2, and grade 4. The subjects were 7 dyslexic, 7 mildly dyslexic, 30 average, and 16 good readers, defined in terms of the discrepancy between standardized reading and intelligence scores. Across the three ages, reader groups did not differ in language comprehension, but did differ in confrontation and rapid automatized naming (RAN), three syntactic measures, and verbal memory. Group strengths and weaknesses were, with few exceptions apparent in kindergarten and maintained throughout. The kindergarten tasks which most effectively predicted reading group membership at grade 4 were giving letter sounds, and rapid naming; these predicted 4th grade reading group at close to 100 percent accuracy. The study, together with a further comparison of average and high IQ good readers, provides an interesting contrast between the role of RAN and Confrontation naming in reading. This work was supported in part by NIHCD grants RO1HD18761 to F. H. Duffy, RO1HD18654 to H. Als, and the Mental Retardation Grant P30HD18655 to C. F. Barlow.