Effects of feedforward and feedback consistency on reading and spelling in dyslexia

Activation time-course of phonological code in silent word recognition in adult readers with and without dyslexia

In skilled adult readers, reading words is generally assumed to rapidly and automatically activate the phonological code. In adults with dyslexia, despite the main consensus on their phonological processing deficits, little is known about the activation time course of this code. The present study investigated this issue in both populations. Participants' accuracy and eye movements were recorded while they performed a visual lexical decision task in which phonological consistency of written words was manipulated. Readers with dyslexia were affected by phonological consistency during second fixation duration of visual word recognition suggesting a late activation of the phonological code. Regarding skilled readers, no influence of phonological consistency was found when the participants were considered a homogeneous population. However, a different pattern emerged when they were divided into two subgroups according to their phonological and semantic abilities: Those who showed better decoding than semantic skills were affected by phonological consistency at the earliest stage of visual word recognition while those who showed better semantic than decoding skills were not affected by this factor at any processing stage. Overall, the findings suggest that the presence of phonological deficits in readers with dyslexia is associated with a delayed activation of phonological representations during reading. In skilled readers, the contribution of phonology varies with their reading profile, i.e., being phonologically or semantically oriented.

Consistency norms for 37,677 english words

Consistency reflects the mapping between spelling and sound. That is, a word is feedforward consistent if its pronunciation matches that of similarly spelled words, and feedback consistent if its spelling matches that of similar pronounced words. For a quasi-regular language such as English, the study of consistency effects on lexical processing has been limited by the lack of readily accessible norms. In order to improve current methodological resources, feedforward (spelling-to-sound) and feedback (sound-to-spelling) consistency measures for 37,677 English words were computed. The consistency measures developed here are operationalized at the composite level for multisyllabic words, and at different sub-syllabic segments (onset, nucleus, coda, oncleus, and rime) for both monosyllabic and multisyllabic words. These measures constitute the largest database of English consistency norms to be developed, and will be a valuable resource for researchers to explore the effects of consistency on lexical processes, such as word recognition and spelling. The norms are available as supplementary material with this paper.

Individual Differences in Phonological Feedback Effects: Evidence for the Orthographic Recoding Hypothesis of Orthographic Learning

Share (1995) has proposed phonological recoding (the translation of letters into sounds) as a self-teaching mechanism through which readers establish complete lexical representations. More recently, McKague et al. (2008) proposed a similar role for orthographic recoding, i.e., feedback from sounds to letters, in building and refining lexical representations. We reasoned that an interaction between feedback consistency measures and spelling ability in a spelling decision experiment would lend support to this hypothesis. In a linear mixed effects logistic regression of accuracy data this interaction was significant. Better spellers but not poorer spellers were immune to feedback effects in deciding if a word is spelled correctly, which is consistent with McKague et al.'s prediction that the impact of phonological feedback on word recognition will diminish when the orthographic representation for an item is fully specified. The study demonstrates the importance of considering individual differences when investigating the role of phonology in reading.

Relative Ease in Creating Detailed Orthographic Representations Contrasted with Severe Difficulties to Maintain Them in Long-term Memory Among Dyslexic Children

Most research into orthographic learning abilities has been conducted in English with typically developing children using reading-based tasks. In the present study, we examined the abilities of French-speaking children with dyslexia to create novel orthographic representations for subsequent use in spelling and to maintain them in long-term memory. Their performance was compared with that of chronological age (CA)-matched and reading age (RA)-matched control children. We used an experimental task designed to provide optimal learning conditions (i.e. 10 spelling practice trials) ensuring the short-term acquisition of the spelling of the target orthographic word forms. After a 1-week delay, the long-term retention of the targets was assessed by a spelling post-test. Analysis of the results revealed that, in the short term, children with dyslexia learned the novel orthographic word forms well, only differing from both CA and RA controls on the initial decoding of the targets and from CA controls on the first two practice trials. In contrast, a dramatic drop was observed in their long-term retention relative to CA and RA controls. These results support the suggestion of the self-teaching hypothesis (Share, 1995) that initial errors in the decoding and spelling of unfamiliar words may hinder the establishment of fully specified novel orthographic representations.

Speed and accuracy of dyslexic versus typical word recognition: an eye-movement investigation

Developmental dyslexia is often characterized by a dual deficit in both word recognition accuracy and general processing speed. While previous research into dyslexic word recognition may have suffered from speed-accuracy trade-off, the present study employed a novel eye-tracking task that is less prone to such confounds. Participants (10 dyslexics and 12 controls) were asked to look at real word stimuli, and to ignore simultaneously presented non-word stimuli, while their eye-movements were recorded. Improvements in word recognition accuracy over time were modeled in terms of a continuous non-linear function. The words' rhyme consistency and the non-words' lexicality (unpronounceable, pronounceable, pseudohomophone) were manipulated within-subjects. Speed-related measures derived from the model fits confirmed generally slower processing in dyslexics, and showed a rhyme consistency effect in both dyslexics and controls. In terms of overall error rate, dyslexics (but not controls) performed less accurately on rhyme-inconsistent words, suggesting a representational deficit for such words in dyslexics. Interestingly, neither group showed a pseudohomophone effect in speed or accuracy, which might call the task-independent pervasiveness of this effect into question. The present results illustrate the importance of distinguishing between speed- vs. accuracy-related effects for our understanding of dyslexic word recognition.

Differential effects of orthographic and phonological consistency in cortex for children with and without reading impairment

One of the central challenges in mastering English is becoming sensitive to consistency from spelling to sound (i.e. phonological consistency) and from sound to spelling (i.e. orthographic consistency). Using functional magnetic resonance imaging (fMRI), we examined the neural correlates of consistency in 9-15-year-old Normal and Impaired Readers during a rhyming task in the visual modality. In line with our previous study [Bolger, D.J., Hornickel, J., Cone, N. E., Burman, D. D., & Booth,J. R. (in press). Neural correlates of orthographic and phonological consistency effects in children. Human Brain Mapping], for Normal Readers, lower phonological and orthographic consistency were associated with greater activation in several regions including bilateral inferior/middle frontal gyri, bilateral anterior cingulate cortex as well as left fusiform gyrus. Impaired Readers activated only bilateral anterior cingulate cortex in response to decreasing consistency. Group comparisons revealed that, relative to Impaired Readers, Normal Readers exhibited a larger response in this network for lower phonological consistency whereas orthographic consistency differences were limited. Lastly, brain-behavior correlations revealed a significant relationship between skill (i.e. Phonological Awareness and non-word decoding) and cortical consistency effects for Impaired Readers in left inferior/middle frontal gyri and left fusiform gyrus. Impaired Readers with higher skill showed greater activation for higher consistency. This relationship was reliably different from that of Normal Readers in which higher skill was associated with greater activation for lower consistency. According to single-route or connectionist models, these results suggest that Impaired Readers with higher skill devote neural resources to representing the mapping between orthography and phonology for higher consistency words, and therefore do not robustly activate this network for lower consistency words.

Spelling consistency affects reading in young Dutch readers with and without dyslexia

Lexical-decision studies with experienced English and French readers have shown that visual-word identification is not only affected by pronunciation inconsistency of a word (i.e., multiple ways to pronounce a spelling body), but also by spelling inconsistency (i.e., multiple ways to spell a pronunciation rime). The aim of this study was to compare the reading behavior of young Dutch readers with dyslexia to the behavior of readers without dyslexia. All students participated in a lexical-decision task in which we presented pronunciation-consistent words and pseudowords. Half of the pronunciation-consistent stimuli were spelling consistent and the other half were spelling inconsistent. All three reader groups, that is, students with dyslexia, age-match students, and reading-match students, read spelling-consistent words faster than spelling-inconsistent words. Overall reading speed of students with dyslexia was similar to that of reading-match students, and was substantially slower than that of age-match students. The results suggest that reading in students with or without dyslexia is similarly affected by spelling inconsistency. Subtle qualitative differences emerged, however, with respect to pseudoword identification. The conclusion was that the findings were best interpreted in terms of a recurrent-feedback model.