Do early musical impairments predict later reading difficulties? A longitudinal study of pre-readers with and without familial risk for dyslexia.

The present longitudinal study investigated the hypothesis that early musical skills (as measured by melodic and rhythmic perception and memory) predict later literacy development via a mediating effect of phonology. We examined 130 French-speaking children, 31 of whom with a familial risk for developmental dyslexia (DD). Their abilities in the three domains were assessed longitudinally with a comprehensive battery of behavioral tests in kindergarten, first grade, and second grade. Using a structural equation modeling approach, we examined potential longitudinal effects from music to literacy via phonology. We then investigated how familial risk for DD may influence these relationships by testing whether atypical music processing is a risk factor for DD. Results showed that children with a familial risk for DD consistently underperformed children without familial risk in music, phonology, and literacy. A small effect of musical ability on literacy via phonology was observed, but may have been induced by differences in stability across domains over time. Furthermore, early musical skills did not add significant predictive power to later literacy difficulties beyond phonological skills and family risk status. These findings are consistent with the idea that certain key auditory skills are shared between music and speech processing, and between DD and congenital amusia. However, they do not support the notion that music perception and memory skills can serve as a reliable early marker of DD, nor as a valuable target for reading remediation. RESEARCH HIGHLIGHTS: Music, phonology, and literacy skills of 130 children, 31 of whom with a familial risk for dyslexia, were examined longitudinally. Children with a familial risk for dyslexia consistently underperformed children without familial risk in musical, phonological, and literacy skills. Structural equation models showed a small effect of musical ability in kindergarten on literacy in second grade, via phonology in first grade. However, early musical skills did not add significant predictive power to later literacy difficulties beyond phonological skills and family risk status.

Eye movements during reading in beginning and skilled readers: Impact of reading level or physiological maturation?

We begin by presenting and examining relevant data in the literature on eye movements in reading, from childhood to adulthood. In particular, we discuss the differences found in eye movements during reading between children in different age groups and with different reading levels and skilled adult readers in terms of word recognition and sentence processing. We then critically discuss two hypotheses that account for the differences between children and adults' eye movement during reading: one being reading age itself - the changes in eye movement patterns in reading are regulated by the level of reading proficiency and its automatization - and the other being the role of maturation of oculomotor control and, consequently, its possible changes in eye movement patterns during reading. Finally, we list gaps in the research field and suggest that future research will benefit from investigating eye movements during reading in ex-illiterate adults who are in the process of learning to read in order to isolate both reading and maturational factors.

Do developmental dyslexia and congenital amusia share underlying impairments?

Developmental dyslexia and congenital amusia have common characteristics. Yet, their possible association in some individuals has been addressed only scarcely. Recently, two converging studies reported a sizable comorbidity rate between these two neurodevelopmental disorders (Couvignou et al., Cognitive Neuropsychology 2019; Couvignou & Kolinsky, Neuropsychologia 2021). However, the reason for their association remains unclear. Here, we investigate the hypothesis of shared underlying impairments between dyslexia and amusia. Fifteen dyslexic children with amusia (DYS+A), 15 dyslexic children without amusia (DYS-A), and two groups of 25 typically developing children matched on either chronological age (CA) or reading level (RL) were assessed with a behavioral battery aiming to investigate phonological and pitch processing capacities at auditory memory, perceptual awareness, and attentional levels. Overall, our results suggest that poor auditory serial-order memory increases susceptibility to comorbidity between dyslexia and amusia and may play a role in the development of the comorbid phenotype. In contrast, the impairments observed in the DYS+A children for auditory item memory, perceptual awareness, and attention might be a consequence of their reduced reading experience combined with weaker musical skills. Comparing DYS+A and DYS-A children suggests that the latter are more resourceful and/or have more effective compensatory strategies, or that their phenotype results from a different developmental trajectory. We will discuss the relevance of these findings for delving into the etiology of these two developmental disorders and address their implications for future research and practice.

Phonological and orthographic processing in basic literacy adults and dyslexic children.

The aim of the present study was to examine the hypothesis that, compared to typically reading children matched on regular word reading, adults with basic literacy (either adult literacy students or adult basic education students) struggle on phonologically demanding tasks but are relatively performant on orthographic demanding tasks, and hence present a performance pattern similar to that of dyslexic children. Using various reading and phoneme awareness tests, we therefore compared the adults to both typically reading children from Grades 3 and 4 and dyslexic children, these two groups being matched to the adults on regular word reading. The dyslexic children were also compared to either chronological age- or reading level-matched children. The hypothesis was only partly supported by the data, as results depended on the subgroup of adults considered. While the literacy students presented poorer phoneme awareness and a somewhat stronger length effect in reading than the dyslexic children, the basic education students outperformed the latter on irregular word reading. The adults, and in particular the literacy students, also relied frequently on orthography in a complex phoneme awareness task. Taken together, these results suggest that adults with basic literacy rely more on visual memory than both dyslexic and typically reading children. This opens the question of whether the peculiar profile of these adults is intrinsic to adult literacy acquisition or is related to the way they are taught and trained to read and write. The results also highlight the need for better characterization of subgroups of adults with basic literacy.

The impact of alphabetic literacy on the perception of speech sounds.

The aim of the present study was to evaluate the impact of literacy on phoneme perception. It built on previous research by using more controlled stimuli than in former studies and by independently examining the impacts of literacy and age on phoneme perception. Participants were adult and children beginning readers, and skilled adult readers. They were presented with identification and discrimination tasks, using a voicing continuum. In addition to examining their categorical perception of speech sounds and the precision of phonemic categories, participants' literacy level was carefully evaluated. The results confirmed that neither age nor literacy modulated categorical perception. However, level of literacy did have a significant impact on the precision of phonemic categories, which was independent from the influence of age.

Comorbidity and cognitive overlap between developmental dyslexia and congenital amusia in children.

Developmental dyslexia and congenital amusia are two specific neurodevelopmental disorders that affect reading and music perception, respectively. Similarities at perceptual, cognitive, and anatomical levels raise the possibility that a common factor is at play in their emergence, albeit in different domains. However, little consideration has been given to what extent they can co-occur. A first adult study suggested a 30% amusia rate in dyslexia and a 25% dyslexia rate in amusia (Couvignou et al., Cognitive Neuropsychology 2019). We present newly acquired data from 38 dyslexic and 38 typically developing children. These were assessed with literacy and phonological tests, as well as with three musical tests: the Montreal Battery of Evaluation of Musical Abilities, a pitch and time change detection task, and a singing task. Overall, about 34% of the dyslexic children were musically impaired, a proportion that is significantly higher than both the estimated 1.5-4% prevalence of congenital amusia in the general population and the rate of 5% observed within the control group. They were mostly affected in the pitch dimension, both in terms of perception and production. Correlations and prediction links were found between pitch processing skills and language measures after partialing out confounding factors. These findings are discussed with regard to cognitive and neural explanatory hypotheses of a comorbidity between dyslexia and amusia.

Impact of literacy on the functional connectivity of vision and language related networks.

Learning to read leads to functional and structural changes in cortical brain areas related to vision and language. Previous evidence suggests that the Visual Word Form Area (VWFA), a region devoted to the recognition of letter strings in literate persons, acts as an interface between both systems. While different studies have performed univariate analyses to study the effects of literacy on brain function, little is known about its impact on whole functional networks, especially when literacy is acquired during adulthood. We investigated functional connectivity in three groups of adults with different literacy status: illiterates, ex-illiterates (i.e., who learned to read during adulthood), and literates (i.e., who learned to read in childhood). We used a data-driven, multivariate whole brain approach (Independent Component Analysis [ICA]) combined with a region of interest (ROI) analysis in order to explore the functional connectivity of the VWFA with four ICA networks related to vision and language functions. ICA allowed for the identification of four networks of interest: left fronto-parietal, auditory, medial visual and lateral visual functional networks, plus a control right fronto-parietal network. We explored the effects literacy on the connectivity between the VWFA and these networks, trying furthermore to disentangle the roles of reading proficiency and age of acquisition (i.e., literacy status) in these changes. Results showed that functional connectivity between the VWFA and the left fronto-parietal and lateral visual networks increased and decreased, respectively, with literacy. Moreover, the functional coupling of the VWFA and the auditory network decreased with literacy. This study provides novel insights in the mechanisms of reading acquisition and brain plasticity, putting to light the emergence of the VWFA as a bridge between language and vision. Further studies are required to characterize the interplay of proficiency and age of reading acquisition, and its relevance to models of brain plasticity across lifespan.

Reading by extracting invariant line junctions in typical and atypical young readers.

We aimed at investigating whether typical and atypical young readers extract vertices (viewpoint-invariant line junctions) in reading, as has been shown for fluent adult readers. In an identification task, we presented partly deleted printed letters, words, and pseudowords, preserving either the vertices or the midsegments of the letters. This allowed assessing the occurrence of a vertex effect, that is, more errors when vertices are partly removed, keeping the midsegments intact, than in the reverse situation. In Experiment 1, the vertex effect was observed on words and pseudowords in three groups of typical readers: 48 adults, 56 beginning readers (Grades 2 and 3), and 42 more advanced readers (Grades 4 and 5). Yet, the effect was smaller in the beginning readers, in relation to their irregular word reading skills. In Experiment 2, we compared 40 children with dyslexia with children selected from Experiment 1 to match them on either chronological age (30 CA controls) or reading level (42 RL controls). Although all groups displayed a vertex effect on words and pseudowords, dyslexic children presented a smaller effect than CA controls without differing from RL controls. The whole result pattern suggests that vertices play an important role in the recognition of written strings not only in skilled adult readers but also in young readers, in relation to their actual reading skills rather than to a specific reading deficit.

Braille readers break mirror invariance for both visual Braille and Latin letters.

For this study, we started from the observation that the poor adequacy of a script to the requirements of the human visual system strongly impacts some aspects of reading expertise (e.g., fluent reading). Here we investigated another of these aspects, namely the ability to break mirror invariance, which makes it hard for readers to ignore the mirrored contrasts of letters even if this hinders performance. In particular, we hypothesized that this ability would be preserved for the visually presented letters of the Braille alphabet despite their poor fit to the constraints of the human visual system, as it did for congenital Braille readers when they explored the same letters through the tactile modality (de Heering, Collignon, & Kolinsky, 2018). To test so, we measured visual Braille readers' mirror costs, indexing for their difficulty to consider mirrored items as identical compared to strictly identical items, for three materials: Braille letters, geometrical shapes and Latin letters, which invariant properties are typically considered as having been selected through cultural evolution because they match the requirements of the visual system. Contrary to people having never experienced Braille, Braille readers' mirror cost was of the same magnitude for Latin letters and Braille letters and steadily increased the more they had experience with the latter material. Both these costs were also stronger than what was observed for geometrical shapes. Overall these results suggest that the poor adequacy of the Braille alphabet to the visual system does not impede Braille readers to break mirror invariance for the Braille material.

Blind readers break mirror invariance as sighted do.

Mirror invariance refers to a predisposition of humans, including infants and animals, which urge them to consider mirrored images as corresponding to the same object. Yet in order to learn to read a written system that incorporates mirrored letters (e.g., vs. in the Latin alphabet), humans learn to break this perceptual bias. Here we examined the role visual experience and input modality play in the emergence of this bias. To this end, we tested congenital blind (CB) participants in two same-different tactile comparison tasks including pairs of mirrored and non-mirrored Braille letters as well as embossed unfamiliar geometric shapes and Latin letters, and compared their results to those of age-matched sighted participants involved in similar but visually-presented tasks. Sighted participants showed a classical pattern of results for their material of expertise, Latin letters. CB's results signed for their expertise with the Braille script compared to the other two materials that they processed according to an internal frame of reference. They also evidenced that they automatically break mirror invariance for different materials explored through the tactile modality, including Braille letters. Altogether, these results demonstrate that learning to read Braille through the tactile modality allows breaking mirror invariance in a comparable way to what is observed in sighted individuals for the mirrored letters of the Latin alphabet.

Peripheral and central contribution to the difficulty of speech in noise perception in dyslexic children.

Noise typically induces both peripheral and central masking of an auditory target. Whereas the idea that a deficit of speech in noise perception is inherent to dyslexia is still debated, most studies have actually focused on the peripheral contribution to the dyslexics' difficulties of perceiving speech in noise. Here, we investigated the respective contribution of both peripheral and central noise in three groups of children: dyslexic, chronological age matched controls (CA), and reading-level matched controls (RL). In all noise conditions, dyslexics displayed significantly lower performance than CA controls. However, they performed similarly or even better than RL controls. Scrutinizing individual profiles failed to reveal a strong consistency in the speech perception difficulties experienced across all noise conditions, or across noise conditions and reading-related performances. Taken together, our results thus suggest that both peripheral and central interference contribute to the poorer speech in noise perception of dyslexic children, but that this difficulty is not a core deficit inherent to dyslexia.

Is There a Relationship Between Speech Identification in Noise and Categorical Perception in Children With Dyslexia?

PURPOSE: Children with dyslexia have been suggested to experience deficits in both categorical perception (CP) and speech identification in noise (SIN) perception. However, results regarding both abilities are inconsistent, and the relationship between them is still unclear. Therefore, this study aimed to investigate the relationship between CP and the psychometric function of SIN perception. METHOD: Sixteen children with dyslexia, 16 chronological-age controls, and 16 reading-level controls were evaluated in CP of a voicing continuum and in consonant identification in both stationary and fluctuating noises. RESULTS: There was a small but significant impairment in speech identification performance of children with dyslexia in stationary noise compared with chronological age-matched controls (but not reading level-matched controls). However, their performance increased in a fluctuating background, hence suggesting normal masking and unmasking effects and preserved sensory processing of speech information. Regarding CP, location of the phoneme boundary differed in the children with dyslexia compared with both control groups. However, scrutinizing individual profiles failed to reveal consistently poor performance in SIN and CP tasks. In addition, there was no significant correlation between CP, SIN perception, and reading scores in the group with dyslexia. CONCLUSIONS: The relationship between the SIN deficit and CP, and how they potentially affect reading in children with dyslexia, remains unclear. However, these results are inconsistent with the notion that children with dyslexia suffer from a low-level temporal processing deficit and rather suggest a role of nonsensory (e.g., attentional) factors in their speech perception difficulties.

Into the Looking Glass: Literacy Acquisition and Mirror Invariance in Preschool and First-Grade Children.

At what point in reading development does literacy impact object recognition and orientation processing? Is it specific to mirror images? To answer these questions, forty-six 5- to 7-year-old preschoolers and first graders performed two same-different tasks differing in the matching criterion-orientation-based versus shape-based (orientation independent)-on geometric shapes and letters. On orientation-based judgments, first graders outperformed preschoolers who had the strongest difficulty with mirrored pairs. On shape-based judgments, first graders were slower for mirrored than identical pairs, and even slower than preschoolers. This mirror cost emerged with letter knowledge. Only first graders presented worse shape-based judgments for mirrored and rotated pairs of reversible (e.g., b-d; b-q) than nonreversible (e.g., e-ә) letters, indicating readers' difficulty in ignoring orientation contrasts relevant to letters.

Does learning to read shape verbal working memory?

Many experimental studies have investigated the relationship between the acquisition of reading and working memory in a unidirectional way, attempting to determine to what extent individual differences in working memory can predict reading achievement. In contrast, very little attention has been dedicated to the converse possibility that learning to read shapes the development of verbal memory processes. In this paper, we present available evidence that advocates a more prominent role for reading acquisition on verbal working memory and then discuss the potential mechanisms of such literacy effects. First, the early decoding activities might bolster the development of subvocal rehearsal, which, in turn, would enhance serial order performance in immediate memory tasks. In addition, learning to read and write in an alphabetical system allows the emergence of phonemic awareness and finely tuned phonological representations, as well as of orthographic representations. This could improve the quality, strength, and precision of lexical representations, and hence offer better support for the temporary encoding of memory items and/or for their retrieval.

Disentangling fast and slow attentional influences of negative and taboo spoken words in the emotional Stroop paradigm.

Although the influence of the emotional content of stimuli on attention has been considered as occurring within trial, recent studies revealed that the presentation of such stimuli would also involve a slow component. The aim of the present study was to investigate fast and slow effects of negative (Exp. 1) and taboo (Exp. 2) spoken words. For this purpose, we used an auditory variant of the emotional Stroop paradigm in which each emotional word was followed by a sequence of neutral words. Replicating results from our previous study, we observed slow but no fast effects of negative and taboo words, which we interpreted as reflecting difficulties to disengage attention from their emotional dimension. Interestingly, while the presentation of a negative word only delayed the processing of the immediately subsequent neutral word, slow effects of taboo words were long-lasting. Nevertheless, such attentional effects were only observed when the emotional words were presented in the first block of trials, suggesting that once participants develop strategies to perform the task, attention-grabbing effects of emotional words disappear. Hence, far from being automatic, the occurrence of these effects would depend on participants' attentional set.

Informational masking of speech in dyslexic children.

Studies evaluating speech perception in noise have reported inconsistent results regarding a potential deficit in dyslexic children. So far, most of them investigated energetic masking. The present study evaluated situations inducing mostly informational masking, which reflects cognitive interference induced by the masker. Dyslexic children were asked to identify a female target syllable presented in quiet, babble, unmodulated, and modulated speech-shaped noise. Whereas their performance was comparable to normal-reading children in quiet, it dropped significantly in all noisy conditions compared to age-, but not reading level-matched controls. Interestingly, noise affected similarly the reception of voicing, place, and manner of articulation in dyslexic and normal-reading children.

Illiterate to literate: behavioural and cerebral changes induced by reading acquisition.

The acquisition of literacy transforms the human brain. By reviewing studies of illiterate subjects, we propose specific hypotheses on how the functions of core brain systems are partially reoriented or 'recycled' when learning to read. Literacy acquisition improves early visual processing and reorganizes the ventral occipito-temporal pathway: responses to written characters are increased in the left occipito-temporal sulcus, whereas responses to faces shift towards the right hemisphere. Literacy also modifies phonological coding and strengthens the functional and anatomical link between phonemic and graphemic representations. Literacy acquisition therefore provides a remarkable example of how the brain reorganizes to accommodate a novel cultural skill.

How Early Does the Brain Distinguish between Regular Words, Irregular Words, and Pseudowords during the Reading Process? Evidence from Neurochronometric TMS.

Cognitive theories on reading propose that the characteristics of written stimuli determine how they are processed in the brain. However, whether the brain distinguishes between regular words, irregular words, and pseudowords already at an early stage of the reading process is still subject to debate. Here we used chronometric TMS to address this issue. During the first 140 msec of regular word, irregular word, and pseudoword reading, TMS was used to disrupt the function of the ventral occipitotemporal, posterior middle temporal, and supramarginal gyri, which are key areas involved in orthographic, semantic, and phonological processing, respectively. Early TMS stimulation delivered on posterior middle temporal and supramarginal gyri affected regular and irregular word, but not pseudoword, reading. In contrast, ventral occipitotemporal disruption affected both word and pseudoword reading. We thus found evidence for an early distinction between word and pseudoword processing in the semantic and phonological systems, but not in the orthographic system.

Informational masking of complex tones in dyslexic children.

In complex auditory scenes, perceiving a given target signal is often complicated by the presence of competing maskers. In addition to energetic masking (EM), which arises because of peripheral interferences between target and maskers at the cochlear level, informational masking (IM), which takes place at a more central level, is also responsible for the difficulties encountered in typical ecological auditory environments. While recent research has led to mixed results regarding a potential speech-perception-in-noise deficit in dyslexic children, most of them actually investigated EM situations. The current study aimed at evaluating dyslexic children's sensitivity to pure IM in complex auditory sequences. Performance of the control normally-reading children increased throughout the experiment, reaching a significantly better level than dyslexics' in the last blocks. Our results provide evidence for a general auditory deficit in noise in dyslexic children. Although due to central mechanisms, this deficit does not seem to stem from a mere auditory attention impairment. Further research is needed to examine the precise nature of the auditory difficulty, and its link with reading acquisition in dyslexic children.