Discrete versus multiple word displays: a re-analysis of studies comparing dyslexic and typically developing children

The metrics of reading speed: understanding developmental dyslexia

We compared reading words and pseudo-words presented in single displays (as typical of psycholinguistic research) with stimuli presented in multiple displays (as typical of real-life conditions and clinical testing) under controlled conditions. Italian sixth-grade children with and without a reading deficit showed an advantage in reading times for multiple over single displays. This finding was partly ascribed to the capacity to overlap the non-decisional component of the response, an effect present in control readers as well as children with dyslexia. Furthermore, there were several indications in the data that the requirement to read sequentially taxes performance by augmenting the relative impact of the experimental manipulations used. This effect was present in both groups of children, but proportionally stronger in children with dyslexia. The study contributes to filling the gap between single and multiple displays, a condition more like real-life situations.

Dyslexia Due to Visual Impairments

Reading involves many different abilities that are necessary or sufficient conditions for fluent and flawless reading. The absence of one necessary or of all sufficient conditions is a cause of dyslexia. The present study investigates whether too short fixation times and an impaired ability to recognize a string of letters simultaneously are causes of dyslexia. The frequency and types of reading mistakes were investigated in a tachistoscopic pseudoword experiment with 100 children with dyslexia to test the impact of too short fixation times and the attempts of children with dyslexia to recognize more letters simultaneously than they can when reading pseudowords. The experiment demonstrates that all types of reading mistakes disappear when the fixation time increases and/or the number of letters that the children try to recognize simultaneously is reduced. The results cannot be interpreted as being due to altered visual crowding, impaired attention, or impaired phonological awareness, but can be regarded as an effect of impaired temporal summation and a dysfunction in the ventral stream of the visual system.

Dyslexia: Causes and Concomitant Impairments

In recent decades, theories have been presented to explain the nature of dyslexia, but the causes of dyslexia remained unclear. Although the investigation of the causes of dyslexia presupposes a clear understanding of the concept of cause, such an understanding is missing. The present paper proposes the absence of at least one necessary condition or the absence of all sufficient conditions as causes for impaired reading. The causes of impaired reading include: an incorrect fixation location, too short a fixation time, the attempt to recognize too many letters simultaneously, too large saccade amplitudes, and too short verbal reaction times. It is assumed that a longer required fixation time in dyslexic readers results from a functional impairment of areas V1, V2, and V3 that require more time to complete temporal summation. These areas and areas that receive input from them, such as the fusiform gyrus, are assumed to be impaired in their ability to simultaneously process a string of letters. When these impairments are compensated by a new reading strategy, reading ability improves immediately.

Palabras, mejor de una en una: los niños con dislexia ante la lectura de palabras presentadas simultáneamente

Diferentes estudios han reportado que los lectores competentes se benefician de la presentación simultánea de palabras durante la lectura. Por otra parte, la existencia de representaciones ortográficas de las palabras parece facilitar el inicio de la codificación fonológica de la palabra contigua, que se iniciaría durante el proceso de articulación de la palabra target. Sin embargo, este beneficio podría no darse en los niños con dislexia, considerando su escasa competencia lectora. El objetivo de este estudio era investigar si los niños con dislexia se benefician de la presentación simultánea de palabras escritas y si esto depende de las características de los estímulos. Para ello, niños con y sin dislexia participaron en dos tareas de lectura. En la primera tarea, las palabras, manipuladas en frecuencia y longitud, se presentaban de manera aislada; mientras que la segunda tarea se trataba de listas de tres palabras, en las que se manipulaba la frecuencia y longitud de la tercera palabra. Los resultados pusieron de relieve las dificultades lectoras en el grupo con dislexia, con peor rendimiento que el grupo control en ambas tareas. Por otra parte, ambos grupos obtuvieron ventaja de la presentación simultánea de palabras, con tiempos previos a la articulación de la palabra menores en la presentación simultánea que en la palabra aislada. Sin embargo, este beneficio no se dio en los tiempos de articulación y exactitud lectora en los niños con dislexia, especialmente cuando se trataba de palabras largas e infrecuentes, sugiriendo que los niños dislexia no alcanzan el mismo nivel de preprocesamiento que los niños del grupo control.

Success Is Not the Entire Story for a Scientific Theory: The Case of the Phonological Deficit Theory of Dyslexia

In a recent paper, Share discussed four different “Common Misconceptions about the Phonological Deficit Theory of Dyslexia” and described this theory as “a model of true scientific progress” and a clear “success story”. In this note, I argue that at least part of the success of this theory is due to the lack of explicit predictions which make it very difficult (if possible) to test its predictions, and, possibly, falsify the theory. Some areas of pertinent research, including categorical phoneme perception, picture naming, and phonological awareness are summarized. Furthermore, two lines of research in which groups of researchers have attempted to formulate more explicit predictions are briefly outlined. It is concluded that, although much research has variously referred to the phonological deficit theory of dyslexia, the resulting large body of evidence presents a complex pattern of results which, in the absence of an explicit formulation of the theory, is extremely difficult to frame within a unitary interpretation. Overall, what seems needed is a theoretical formulation that, on the one hand, can account for the complex pattern of available evidence and, on the other hand, provide testable predictions for future research.

Word- and Text-Level Processes Contributing to Fluent Reading of Word Lists and Sentences

In this study, we investigated how word- and text-level processes contribute to different types of reading fluency measures. We aimed to increase our understanding of the underlying processes necessary for fluent reading. The sample included 73 Dutch Grade 3 children, who were assessed on serial word reading rate (familiar words), word-list reading fluency (increasingly difficult words), and sentence reading fluency. Word-level processes were individual word recognition speed (discrete word reading) and sequential processing efficiency (serial digit naming). Text-level processes were receptive vocabulary and syntactic skills. The results showed that word- and text-level processes combined accounted for a comparable amount of variance in all fluency outcomes. Both word-level processes were moderate predictors of all fluency outcomes. However, vocabulary only moderately predicted sentence reading fluency, and syntactic skills merely contributed to sentence reading fluency indirectly through vocabulary. The findings indicate that sequential processing efficiency has a crucial role in reading fluency across various measures besides individual word recognition speed. Additionally, text-level processes come into play when complexity and context availability of fluency measures increases, but the exact timing requires further study. Findings are discussed in terms of future directions and their possible value for diagnostic assessment and intervention of reading difficulties.

Training RAN or reading? A telerehabilitation study on developmental dyslexia

Rehabilitation procedures recommended for developmental dyslexia (DD) are still not fully defined, and only few studies directly compare different types of training. This study compared a training (Reading Trainer) working on the reading impairment with one (Run the RAN) working on the rapid automatized naming (RAN) impairment, one of the main cognitive deficits associated with DD. Two groups of DD children (N = 45) equivalent for age, sex, full IQ, and reading speed were trained either by Reading Trainer (n = 21) or by Run the RAN (n = 24); both trainings required an intensive home exercise, lasting 3 months. Both trainings showed significant improvements in reading speed and accuracy of passages and words. Bypassing the use of alphanumeric stimuli, but empowering the cognitive processes underlying reading, training RAN may be a valid tool in children with reading difficulties opening new perspectives for children with severe impairments or, even, at risk of reading difficulties.

Using Serial and Discrete Digit Naming to Unravel Word Reading Processes

During reading acquisition, word recognition is assumed to undergo a developmental shift from slow serial/sublexical processing of letter strings to fast parallel processing of whole word forms. This shift has been proposed to be detected by examining the size of the relationship between serial- and discrete-trial versions of word reading and rapid naming tasks. Specifically, a strong association between serial naming of symbols and single word reading suggests that words are processed serially, whereas a strong association between discrete naming of symbols and single word reading suggests that words are processed in parallel as wholes. In this study, 429 Grade 1, 3, and 5 English-speaking Canadian children were tested on serial and discrete digit naming and word reading. Across grades, single word reading was more strongly associated with discrete naming than with serial naming of digits, indicating that short high-frequency words are processed as whole units early in the development of reading ability in English. In contrast, serial naming was not a unique predictor of single word reading across grades, suggesting that within-word sequential processing was not required for the successful recognition for this set of words. Factor mixture analysis revealed that our participants could be clustered into two classes, namely beginning and more advanced readers. Serial naming uniquely predicted single word reading only among the first class of readers, indicating that novice readers rely on a serial strategy to decode words. Yet, a considerable proportion of Grade 1 students were assigned to the second class, evidently being able to process short high-frequency words as unitized symbols. We consider these findings together with those from previous studies to challenge the hypothesis of a binary distinction between serial/sublexical and parallel/lexical processing in word reading. We argue instead that sequential processing in word reading operates on a continuum, depending on the level of reading proficiency, the degree of orthographic transparency, and word-specific characteristics.

Spelling across Tasks and Levels of Language in a Transparent Orthography

The paper reports the results of two studies on the spelling performance of 1st graders in a transparent writing system. The spelling performance of Italian children was assessed to determine the cross-task relationship between spelling to dictation and spontaneous spelling at the single word level (Study 1) and at the text level (Study 2), respectively. In study 1, 132 Italian children's spelling performance was assessed in 1st grade through two standardized tasks, i.e., word dictation, and spontaneous word spelling. In study 2, spelling performance of 81 Italian children was assessed in 1st grade through two tasks, i.e., text dictation, and spontaneous text spelling. In Study 1, spelling words and pseudo-words to dictation was found to be more difficult than spontaneous spelling of words. This effect was verified for all children (including low achievers and spelling impaired). The moderate correlation found between spelling to dictation and spontaneous spelling indicated that the two tasks are supported by partially different spelling processes and confirmed suggestions for including both types of spelling assessments in the school. In Study 2, children's spelling performances were not dependent across the two tasks (i.e., spelling a text under dictation or spontaneously). The two tasks shared the level of difficulty but performance in one task was not predictive of performance in the second task. Strong individual differences between children were found at the text level as a function of task. Similar to Study 1, the moderate correlation between spelling text to dictation and spontaneous spelling confirmed the usefulness of adopting both spelling assessments at school.

Predicting Reading and Spelling Disorders: A 4-Year Prospective Cohort Study

In this 4-year prospective cohort study, children with a reading and spelling disorder, children with a spelling impairment, and children without a reading and/or spelling disorder (control group) in a transparent orthography were identified in third grade, and their emergent literacy performances in kindergarten compared retrospectively. Six hundred and forty-two Italian children participated. This cohort was followed from the last year of kindergarten to third grade. In kindergarten, the children were assessed in phonological awareness, conceptual knowledge of writing systems and textual competence. In third grade, 18 children with a reading and spelling impairment and 13 children with a spelling impairment were identified. Overall, conceptual knowledge of the writing system was the only statistically significant predictor of the clinical samples. No differences were found between the two clinical samples.