Phonological and orthographic coding in deaf skilled readers.

Written language is very important in daily life. However, most deaf people do not achieve good reading levels compared to their hearing peers. Previous research has mainly focused on their difficulties when reading in a language with an opaque orthography such as English. In the present study, we investigated visual word recognition of deaf adult skilled readers while reading in Spanish, a language with a transparent orthography, for which obligatory phonological mediation has been claimed. Experiment 1 showed a pseudohomophone inhibitory effect in hearing but not in deaf people. Experiment 2 showed similar orthographic sensitivity, as measured by the transposed-letter effect, for both groups. These results suggest that deaf skilled readers do not rely on phonological mediation, while maintaining the same level of orthographic sensitivity as hearing readers, thus suggesting that the use of phonological coding is not required to access the lexicon and meaning in a language with a transparent orthography.

Working memory deficits in boys with attention deficit/hyperactivity disorder (ADHD): An examination of orthographic coding and episodic buffer processes.

The episodic buffer component of working memory was examined in children with attention deficit/hyperactivity disorder (ADHD) and typically developing peers (TD). Thirty-two children (ADHD = 16, TD = 16) completed three versions of a phonological working memory task that varied with regard to stimulus presentation modality (auditory, visual, or dual auditory and visual), as well as a visuospatial task. Children with ADHD experienced the largest magnitude working memory deficits when phonological stimuli were presented via a unimodal, auditory format. Their performance improved during visual and dual modality conditions but remained significantly below the performance of children in the TD group. In contrast, the TD group did not exhibit performance differences between the auditory- and visual-phonological conditions but recalled significantly more stimuli during the dual-phonological condition. Furthermore, relative to TD children, children with ADHD recalled disproportionately fewer phonological stimuli as set sizes increased, regardless of presentation modality. Finally, an examination of working memory components indicated that the largest magnitude between-group difference was associated with the central executive. Collectively, these findings suggest that ADHD-related working memory deficits reflect a combination of impaired central executive and phonological storage/rehearsal processes, as well as an impaired ability to benefit from bound multimodal information processed by the episodic buffer.

Orthographic Coding: Brain Activation for Letters, Symbols, and Digits.

The present experiment investigates the input coding mechanisms of 3 common printed characters: letters, numbers, and symbols. Despite research in this area, it is yet unclear whether the identity of these 3 elements is processed through the same or different brain pathways. In addition, some computational models propose that the position-in-string coding of these elements responds to general flexible mechanisms of the visual system that are not character-specific, whereas others suggest that the position coding of letters responds to specific processes that are different from those that guide the position-in-string assignment of other types of visual objects. Here, in an fMRI study, we manipulated character position and character identity through the transposition or substitution of 2 internal elements within strings of 4 elements. Participants were presented with 2 consecutive visual strings and asked to decide whether they were the same or different. The results showed: 1) that some brain areas responded more to letters than to numbers and vice versa, suggesting that processing may follow different brain pathways; 2) that the left parietal cortex is involved in letter identity, and critically in letter position coding, specifically contributing to the early stages of the reading process; and that 3) a stimulus-specific mechanism for letter position coding is operating during orthographic processing.

Deep generative learning of location-invariant visual word recognition.

It is widely believed that orthographic processing implies an approximate, flexible coding of letter position, as shown by relative-position and transposition priming effects in visual word recognition. These findings have inspired alternative proposals about the representation of letter position, ranging from noisy coding across the ordinal positions to relative position coding based on open bigrams. This debate can be cast within the broader problem of learning location-invariant representations of written words, that is, a coding scheme abstracting the identity and position of letters (and combinations of letters) from their eye-centered (i.e., retinal) locations. We asked whether location-invariance would emerge from deep unsupervised learning on letter strings and what type of intermediate coding would emerge in the resulting hierarchical generative model. We trained a deep network with three hidden layers on an artificial dataset of letter strings presented at five possible retinal locations. Though word-level information (i.e., word identity) was never provided to the network during training, linear decoding from the activity of the deepest hidden layer yielded near-perfect accuracy in location-invariant word recognition. Conversely, decoding from lower layers yielded a large number of transposition errors. Analyses of emergent internal representations showed that word selectivity and location invariance increased as a function of layer depth. Word-tuning and location-invariance were found at the level of single neurons, but there was no evidence for bigram coding. Finally, the distributed internal representation of words at the deepest layer showed higher similarity to the representation elicited by the two exterior letters than by other combinations of two contiguous letters, in agreement with the hypothesis that word edges have special status. These results reveal that the efficient coding of written words-which was the model's learning objective-is largely based on letter-level information.

Codificação fonológica e ortográfica na dislexia de desenvolvimento: evidência de um estudo de caso / Phonological and orthographic coding in developmental dyslexia: Evidence from a case study

O presente estudo investiga a habilidade de codificação fonológica e ortográfica de uma criança com dificuldade de leitura de base fonológica (Idade = 12 anos e 8 meses). Quinze crianças com desenvolvimento típico para as suas idades cronológicas (Idade Média = 8 anos e 7 meses), cuja habilidade de ler palavras era semelhante à da criança disléxica, também participaram do estudo. A codificação fonológica e ortográfica foi avaliada por meio de um ditado de palavras contendo relações letra-som mais ou menos regulares. Os resultados questionam a hipótese de que a habilidade de codificação ortográfica seja superior à habilidade de codificação fonológica na dislexia do desenvolvimento. Embora a criança com dificuldade de leitura tenha apresentado desempenho semelhante ao dos leitores normais nas palavras com regras contextuais, seu desempenho foi muito inferior nas palavras contendo sons cuja grafia é ambígua. Os resultados também sugerem que, relativamente a leitores típicos, crianças com dificuldade de leitura podem ter dificuldade em fazer uso de regularidades morfossintáticas para escrever palavras(AU)

The present study investigates the phonological and orthographic skills of a Brazilian Portuguese-speaking child with a history of persistent reading difficulties (Age = 12 years and 8 months old). Fifteen typical readers with similar reading ability participated as controls (Mean Age = 8 years and 7 months old). Phonological and orthographic coding skills were evaluated through the ability to spell words that varied with regard to the more or less regular nature of their letter-sound correspondences. Results question the hypothesis that orthographic coding skills are superior to phonological coding skills in developmental dyslexia. Although the reading disabled child performed similarly to controls on words containing contextual rules, her performance was substantially inferior on words containing sounds whose spelling is ambiguous. Results also suggest that, relative to typical readers, dyslexic readers may have difficulty in making use of morphosyntactic regularities to spell words(AU)

Codificação fonológica e ortográfica na dislexia de desenvolvimento: evidência de um estudo de caso / Phonological and orthographic coding in developmental dyslexia: evidence from a case study

O presente estudo investiga a habilidade de codificação fonológica e ortográfica de uma criança com dificuldade de leitura de base fonológica (Idade = 12 anos e 8 meses). Quinze crianças com desenvolvimento típico para as suas idades cronológicas (Idade Média = 8 anos e 7 meses), cuja habilidade de ler palavras era semelhante à da criança disléxica, também participaram do estudo. A codificação fonológica e ortográfica foi avaliada por meio de um ditado de palavras contendo relações letra-som mais ou menos regulares. Os resultados questionam a hipótese de que a habilidade de codificação ortográfica seja superior à habilidade de codificação fonológica na dislexia do desenvolvimento. Embora a criança com dificuldade de leitura tenha apresentado desempenho semelhante ao dos leitores normais nas palavras com regras contextuais, seu desempenho foi muito inferior nas palavras contendo sons cuja grafia é ambígua. Os resultados também sugerem que, relativamente a leitores típicos, crianças com dificuldade de leitura podem ter dificuldade em fazer uso de regularidades morfossintáticas para escrever palavras.

The present study investigates the phonological and orthographic skills of a Brazilian Portuguese-speaking child with a history of persistent reading difficulties (Age = 12 years and 8 months old). Fifteen typical readers with similar reading ability participated as controls (Mean Age = 8 years and 7 months old). Phonological and orthographic coding skills were evaluated through the ability to spell words that varied with regard to the more or less regular nature of their letter-sound correspondences. Results question the hypothesis that orthographic coding skills are superior to phonological coding skills in developmental dyslexia. Although the reading disabled child performed similarly to controls on words containing contextual rules, her performance was substantially inferior on words containing sounds whose spelling is ambiguous. Results also suggest that, relative to typical readers, dyslexic readers may have difficulty in making use of morphosyntactic regularities to spell words.