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Delayed development of phonological constancy in toddlers at family risk for dyslexia
Abstract
Phonological constancy refers to infants' ability to disregard variations in the phonetic realisation of speech sounds that do not indicate lexical contrast, e.g., when listening to accented speech. In typically-developing infants, this ability develops between 15- and 19-months of age, coinciding with the consolidation of infants' native phonological competence and vocabulary growth. Here we investigated the developmental time course of phonological constancy in infants at family risk for developmental dyslexia, using a longitudinal design. Developmental dyslexia is a disorder affecting the acquisition of reading and spelling skills, and it also affects early auditory processing, speech perception, and lexical acquisition. Infants at-risk and not at-risk for dyslexia, based on a family history of dyslexia, participated when they were 15-, 19-, and 26-months of age. Phonological constancy was indexed by comparing at-risk and not at-risk infants' ability to recognise familiar words in two preferential looking tasks: (1) a task using words presented in their native accent, and (2) a task using words presented in a non-native accent. We expected a delay in phonological constancy for the at-risk infants. As predicted, in the non-native accent task, not at-risk infants recognised familiar words by 19 months, but at-risk infants did not. The control infants thus exhibited phonological constancy. By 26 months, at-risk toddlers did show successful word recognition in the native accent task. However, for the non-native accent task at 26 months, neither at-risk nor control infants showed familiar word recognition. These findings are discussed in terms of the impact of family risk for dyslexia on toddlers' consolidation of early phonological and lexical skills.
... Accordingly, deficits in these skills in individuals with (a risk for) developmental dyslexia have been widely reported, making rise time sensitivity and speech-in-noise perception, next to addressing specific reading skills, interesting targets for reading intervention programs. Longitudinal study designs which shed light on developmental trajectories of speech perception skills in children with or without a risk for dyslexia are however still rare Kalashnikova et al., 2019), yet crucial to determine the potential onset of auditory problems in dyslexia and define the optimal timing for (auditory) interventions. The current study therefore alludes to (1) longitudinally compare the development of speech perception skills in pre-readers with or without an elevated cognitive risk for developmental dyslexia and (2) investigate the added value of an auditory intervention, specifically targeting rise time sensitivity in at-risk pre-readers. ...
... Prosodic neural entrainment and the abovementioned temporal auditory processing skills measured at the pre-reading phase were also found to predict later literacy development (Law et al., 2017;Vanvooren et al., 2017;Critten et al., 2021;Ríos-López et al., 2022), further supporting the Temporal Sampling Framework rationale. Longitudinal studies specifically comparing growth trajectories between children at risk for dyslexia and typically developing peers regarding auditory processing skills are however scant Kalashnikova et al., 2019), but might be relevant to determine the onset of potential auditory processing problems and to define the optimal timing for auditory interventions in dyslexia. ...
Developmental dyslexia is considered to be most effectively addressed with preventive phonics-based interventions, including grapheme-phoneme coupling and blending exercises. These intervention types require intact speech perception abilities, given their large focus on exercises with auditorily presented phonemes. Yet some children with (a risk for) dyslexia experience problems in this domain due to a poorer sensitivity to rise times, i.e., rhythmic acoustic cues present in the speech envelope. As a result, the often subtle speech perception problems could potentially constrain an optimal response to phonics-based interventions in at-risk children. The current study therefore aimed (1) to extend existing research by examining the presence of potential speech perception deficits in pre-readers at cognitive risk for dyslexia when compared to typically developing peers and (2) to explore the added value of a preventive auditory intervention for at-risk pre-readers, targeting rise time sensitivity, on speech perception and other reading-related skills. To obtain the first research objective, we longitudinally compared speech-in-noise perception between 28 5-year-old pre-readers with and 30 peers without a cognitive risk for dyslexia during the second half of the third year of kindergarten. The second research objective was addressed by exploring growth in speech perception and other reading-related skills in an independent sample of 62 at-risk 5-year-old pre-readers who all combined a 12-week preventive phonics-based intervention (GraphoGame-Flemish) with an auditory story listening intervention. In half of the sample, story recordings contained artificially enhanced rise times (GG-FL_EE group, n = 31), while in the other half, stories remained unprocessed (GG-FL_NE group, n = 31; Clinical Trial Number S60962—https://www.uzleuven.be/nl/clinical-trial-center). Results revealed a slower speech-in-noise perception growth in the at-risk compared to the non-at-risk group, due to an emerged deficit at the end of kindergarten. Concerning the auditory intervention effects, both intervention groups showed equal growth in speech-in-noise perception and other reading-related skills, suggesting no boost of envelope-enhanced story listening on top of the effect of combining GraphoGame-Flemish with listening to unprocessed stories. These findings thus provide evidence for a link between speech perception problems and dyslexia, yet do not support the potential of the auditory intervention in its current form.
... Thiessen et al., 2005 for a similar rationale in word segmentation) 6 . For the familiar word paradigm, there are only very few studies with children older than 19 months (Carbajal et al., 2021), who are typically tested with non-native accents or with specific populations (Best et al., 2009;van Heugten and Johnson, 2014;Kalashnikova et al., 2016). van Heugten and Johnson (2014) report an interaction between word type and age and suggest that "over time, infants start preferring to listen to known over nonsense words" (p. ...
... 344). Kalashnikova et al. (2016) tested a control group of 26-month-old children with familiar accents and showed a reduction of the familiar word preference for 26-month-old children. ...
Variability is pervasive in spoken language, in particular if one is exposed to two varieties of the same language (e.g., the standard variety and a dialect). Unlike in bilingual settings, standard and dialectal forms are often phonologically related, increasing the variability in word forms (e.g., German Fuß “foot” is produced as [fus] in Standard German and as [fs] in the Alemannic dialect). We investigate whether dialectal variability in children’s input affects their ability to recognize words in Standard German, testing non-dialectal vs. dialectal children. Non-dialectal children, who typically grow up in urban areas, mostly hear Standard German forms, and hence encounter little segmental variability in their input. Dialectal children in turn, who typically grow up in rural areas, hear both Standard German and dialectal forms, and are hence exposed to a large amount of variability in their input. We employ the familiar word paradigm for German children aged 12–18 months. Since dialectal children from rural areas are hard to recruit for laboratory studies, we programmed an App that allows all parents to test their children at home. Looking times to familiar vs. non-familiar words were analyzed using a semi-automatic procedure based on neural networks. Our results replicate the familiarity preference for non-dialectal German 12–18-month-old children (longer looking times to familiar words than vs. non-familiar words). Non-dialectal children in the same age range, on the other hand, showed a novelty preference. One explanation for the novelty preference in dialectal children may be more mature linguistic processing, caused by more variability of word forms in the input. This linguistic maturation hypothesis is addressed in Experiment 2, in which we tested older children (18–24-month-olds). These children, who are not exposed to dialectal forms, also showed a novelty preference. Taken together, our findings show that both dialectal and non-dialectal German children recognized the familiar Standard German word forms, but their looking pattern differed as a function of the variability in the input. Frequent exposure to both dialectal and Standard German word forms may hence have affected the nature of (prelexical and/or) lexical representations, leading to more mature processing capacities.
... La mayoría de los estudios muestran que un factor importante a tener en cuenta es la condición de riesgo familiar (RF) de dislexia del infante, ya que influye en el desarrollo de la alfabetización por sus vínculos con la capacidad de decodificación y la comprensión lectora (Van Viersen et al., 2018). Así, por ejemplo, ya en niños de 15 meses se identifican déficits en las habilidades fonológicas y en el procesamiento auditivo y en niños de 19 meses dificultades en el aprendizaje de nuevo vocabulario (Kalashnikova et al., 2019;Kalashnikova et al., 2020). El alumnado con RF presenta generalmente deficiencias en las habilidades de lectura, conciencia de fonemas, ortografía, vocabulario y gramática, las cuales en su mayoría persisten hasta los cursos de Educación Primaria (Caglar-Ryeng et al., 2019;Hayiou-Thomas et al., 2017). ...
... According to the auditory precision account of child language learning, individual differences in auditory processing are associated with lower-order phonetic processing outcomes (e.g., speech-in-noise perception) as well as higher-order linguistic skills (e.g., vocabulary and morphosyntax; Anvari et al., 2002;Bavin et al., 2010;Boets et al., 2008;Talcott et al., 2000;Tierney et al., 2021). Kalashnikova et al. (2019) provided longitudinal evidence regarding how auditory processing influences L1 vocabulary development over the first 3 years of life. Toddlers with difficulties discriminating certain dimensions of sounds are more likely to demonstrate slower phonological, lexical, and morphosyntactic processing later in development, which can in turn lead to more global language problems such as dyslexia (Casini et al., 2018 for duration;Goswami et al., 2011 for amplitude rise time; McArthur & Bishop, 2005 for fundamental frequency; but see Rosen, 2003;Schulte-Körne & Bruder, 2010 for their counterarguments regarding the causal relationship between auditory processing and L1 impairment). ...
Public Significance Statement
Everyone has a unique skill set when it comes to processing general characteristics of sounds, such as pitch and duration. An emerging theory proposes that individual differences in how well we can perceive sound can impact how quickly, effectively, and easily we learn our first and second languages. To date, auditory processing has traditionally been considered as a bottom-up, automatic, and isolated phenomenon. Following the interaction view, however, we argue that auditory processing can be considered a multidimensional phenomenon that encompasses not only the perception of acoustic characteristics (perceptual proficiency), but also the direction of attention towards specific acoustical elements (cognitive proficiency) and the transformation of auditory information into motor output (motoric proficiency). Indeed, recent studies have introduced new concepts of auditory processing that extend beyond mere acuity to include aspects such as attention and integration. In our study involving 102 Chinese English learners, we empirically examined the extent to which a model incorporating not just perceptual, but also cognitive and motoric facets of auditory processing could account for additional variance in language learning outcomes. Our findings align with an expanding body of evidence suggesting that auditory processing, which includes perceptual, cognitive, and motoric components, plays a pivotal role in language learning throughout the lifespan.
... If atypical neural synchronization is present from before birth, then over developmental time, affected children may develop phonological and/or syntactic deficits long before they enter school and begin learning to read. There is already behavioral infant and toddler data consistent with such a developmental trajectory from studies of participants at family risk for dyslexia (Kalashnikova et al., , 2019a. ...
Neural synchronization to amplitude-modulated noise at three frequencies (2 Hz, 5 Hz, 8 Hz) thought to be important for syllable perception was investigated in English-speaking school-aged children. The theoretically-important delta-band (~2Hz, stressed syllable level) was included along with two syllable-level rates. The auditory steady state response (ASSR) was recorded using EEG in 36 7-to-12-year-old children. Half of the sample had either dyslexia or dyslexia and DLD (developmental language disorder). In comparison to typically-developing children, children with dyslexia or with dyslexia and DLD showed reduced ASSRs for 2 Hz stimulation but similar ASSRs at 5 Hz and 8 Hz. These novel data for English ASSRs converge with prior data suggesting that children with dyslexia have atypical synchrony between brain oscillations and incoming auditory stimulation at ~ 2 Hz, the rate of stressed syllable production across languages. This atypical synchronization likely impairs speech processing, phonological processing, and possibly syntactic processing, as predicted by Temporal Sampling theory.
... The neural decoding method employed here suggests that differences in phonological representation are indeed present for low-frequency speech information. This conclusion accords well with the linguistic data gathered by recent longitudinal studies of infants at family risk for developmental dyslexia, who show amplitude rise time discrimination difficulties from age 10 months as well as poorer early word learning and poorer phonological development Kalashnikova, Goswami, & Burnham, 2019a;Kalashnikova, Goswami, & Burnham, 2019b;Kalashnikova, Goswami, & Burnham, 2020). Nevertheless, the strongest test of this conclusion about phonological representations would be a demonstration that speech production is also atypical in dyslexia regarding the specification of speech prosody. ...
The amplitude envelope of speech carries crucial low-frequency acoustic information that assists linguistic decoding. The sensory-neural Temporal Sampling (TS) theory of developmental dyslexia proposes atypical encoding of speech envelope information < 10 Hz, leading to atypical phonological representations. Here a backward linear TRF model and story listening were employed to estimate the speech information encoded in the electroencephalogram in the canonical delta, theta and alpha bands by 9-year-old children with and without dyslexia. TRF decoding accuracy provided an estimate of how faithfully the children’s brains encoded low-frequency envelope information. Between-group analyses showed that the children with dyslexia exhibited impaired reconstruction of speech information in the delta band. However, when the quality of speech encoding for each child was estimated using child-by-child decoding models, then the dyslexic children did not differ from controls. This suggests that children with dyslexia encode neither “noisy” nor “normal” representations of the speech signal, but different representations.
... Open Sci. 9: 211855 constancy (recognizing the same word produced by different speakers; see [63,64]). Rise time detection in infancy showed significant longitudinal associations with vocabulary size at age 3 years [65], and by age 4 non-speech rhythm deficits were present in the at-risk group (using the same musical beat perception task used by Huss et al. [37]; see [66]. In studies with at-risk pre-schoolers conducted in English and Dutch, rise time measured in pre-schoolers aged 3-5 years predicted phonological awareness, letter knowledge and reading at ages 6 and 7 years [67,68]. ...
All human infants acquire language, but their brains do not know which language/s to prepare for. This observation suggests that there are fundamental components of the speech signal that contribute to building a language system, and fundamental neural processing mechanisms that use these components, which are shared across languages. Equally, disorders of language acquisition are found across all languages, with the most prevalent being developmental language disorder (approx. 7% prevalence), where oral language comprehension and production is atypical, and developmental dyslexia (approx. 7% prevalence), where written language acquisition is atypical. Recent advances in auditory neuroscience, along with advances in modelling the speech signal from an amplitude modulation (AM, intensity or energy change) perspective, have increased our understanding of both language acquisition and these developmental disorders. Speech rhythm patterns turn out to be fundamental to both sensory and neural linguistic processing. The rhythmic routines typical of childcare in many cultures, the parental practice of singing lullabies to infants, and the ubiquitous presence of BabyTalk (infant-directed speech) all enhance the fundamental AM components that contribute to building a linguistic brain.
... Children with dyslexia fail to acquire efficient reading and spelling skills despite adequate tuition and an absence of overt sensory and/ or neural deficits (Lyon et al., 2003), and numerous behavioural studies reveal associated difficulties in identifying and manipulating phonological units in oral tasks at all linguistic levels: prosody, syllable, onset-rime and phoneme (Snowling, 2000;Goswami, 2015). Phonological difficulties can even be identified in infants and toddlers at family (genetic) risk for dyslexia (Kalashnikova et al., 2019(Kalashnikova et al., , 2020. If reading is defined as the cognitive process of understanding a visual code for spoken language (Ziegler and Goswami, 2005), then these multiple difficulties with the phonology of the spoken language can be understood developmentally. ...
According to the sensory-neural Temporal Sampling theory of developmental dyslexia, neural sampling of auditory information at slow rates (<10 Hz, related to speech rhythm) is atypical in dyslexic individuals, particularly in the delta band (0.5–4 Hz). Here we examine the underlying neural mechanisms related to atypical sampling using a simple repetitive speech paradigm. Fifty-one children (21 control children [15M, 6F] and 30 children with dyslexia [16M, 14F]) aged 9 years with or without developmental dyslexia watched and listened as a ‘talking head’ repeated the syllable “ba” every 500 ms, while EEG was recorded. Occasionally a syllable was “out of time”, with a temporal delay calibrated individually and adaptively for each child so that it was detected around 79.4% of the time by a button press. Phase consistency in the delta (rate of stimulus delivery), theta (speech-related) and alpha (control) bands was evaluated for each child and each group. Significant phase consistency was found for both groups in the delta and theta bands, demonstrating neural entrainment, but not the alpha band. However, the children with dyslexia showed a different preferred phase and significantly reduced phase consistency compared to control children, in the delta band only. Analysis of pre- and post-stimulus angular velocity of group preferred phases revealed that the children in the dyslexic group showed an atypical response in the delta band only. The delta-band pre-stimulus angular velocity (−130 ms to 0 ms) for the dyslexic group appeared to be significantly faster compared to the control group. It is concluded that neural responding to simple beat-based stimuli may provide a unique neural marker of developmental dyslexia. The automatic nature of this neural response may enable new tools for diagnosis, as well as opening new avenues for remediation.
... Overall, the data presented here provide support for the importance of considering the child's developmental trajectory when exploring differences in speech-brain alignment in participants with dyslexia. Recent infant data from participants at family risk for dyslexia ( Kalashnikova et al., , 2019a( Kalashnikova et al., , 2019b ) support the developmental view that auditory impairments in infancy lead to phonological impairments in toddlerhood and early childhood, which then in turn cause reading impairments once schooling commences ( Goswami, 2020 ). The earliest auditory impairments in dyslexia would be expected to affect the extraction of syllable stress patterns, speech rhythm and prosody, all of which are exaggerated in IDS in order to facilitate language learning ( Leong et al., 2017 ). ...
Phonological difficulties characterise individuals with dyslexia across languages. Currently debated is whether these difficulties arise from atypical neural sampling of (or entrainment to) auditory information in speech at slow rates (<10 Hz, related to speech rhythm), faster rates, or neither. MEG studies with adults suggest that atypical sampling in dyslexia affects faster modulations in the neurophysiological gamma band, related to phoneme-level representation. However, dyslexic adults have had years of reduced experience in converting graphemes to phonemes, which could itself cause atypical gamma-band activity. The present study was designed to identify specific linguistic timescales at which English children with dyslexia may show atypical entrainment. Adopting a developmental focus, we hypothesised that children with dyslexia would show atypical entrainment to the prosodic and syllable-level information that is exaggerated in infant-directed speech and carried primarily by amplitude modulations <10Hz. MEG was recorded in a naturalistic story-listening paradigm. The modulation bands related to different types of linguistic information were derived directly from the speech materials, and lagged coherence at multiple temporal rates spanning 0.9-40 Hz was computed. Group differences in lagged speech-brain coherence between children with dyslexia and control children were most marked in neurophysiological bands corresponding to stress and syllable-level information (<5Hz in our materials), and phoneme-level information (12-40 Hz). Functional connectivity analyses showed network differences between groups in both hemispheres, with dyslexic children showing significantly reduced global network efficiency. Global network efficiency correlated with dyslexic children's oral language development and with control children's reading development. These developmental data suggest that dyslexia is characterised by atypical neural sampling of auditory information at slower rates. They also throw new light on the nature of the gamma band temporal sampling differences reported in MEG dyslexia studies with adults.
... We expected the atrisk four-year-olds to perform at the same level as the not at-risk children on the comprehension test of PAL, but to perform significantly more poorly on the retrieval test of PAL. Even though the dyslexia status of these children was unknown at the time of testing, our previous investigations with this cohort demonstrate that compared to their NAR peers, children in the AR group demonstrate deficits in auditory and linguistic processing assessed from 10 to 19 months of age (Kalashnikova, Goswami, & Burnham, 2018, 2019a, 2020, as well as deficits in verbal processing (vocabulary acquisition) at 3 years (Kalashnikova, Goswami, & Burnham, 2019b). In order to assess the emerging literacy skills in our young sample, we measured early letter knowledge. ...
Visual-verbal-paired associate learning (PAL) is strongly related to reading acquisition, possibly indexing a distinct cross-modal mechanism for learning letter-sound associations. We measured linguistic abilities (nonword repetition, vocabulary size) longitudinally at 3.5 and 4.0 years, and visual-verbal PAL and letter knowledge at 4.0 and 4.5 years, in pre-reading children either at family risk for dyslexia (N = 27) or not (N = 25). Only nonword repetition predicted individual differences in later letter-sound knowledge, and PAL did not make a cross-sectional nor a longitudinal contribution. The data show a continuous relationship between linguistic processing abilities and letter-sound learning, with no independent role for PAL.
... Indeed, infants at family risk of dyslexia already show impaired discrimination of amplitude rise times by 10 months of age, long before either reading or phonological awareness are acquired . Furthermore, these same infants show impaired phonological learning in toddlerhood (Kalashnikova, Goswami, & Burnham, 2019a). Accordingly, the relation between auditory sensory impairments and the development of phonological skills, and consequently reading, appears to be a causal one. ...
Phonological difficulties characterize children with developmental dyslexia across languages, but whether impaired auditory processing underlies these phonological difficulties is debated. Here the causal question is addressed by exploring whether individual differences in sensory processing predict the development of phonological awareness in 86 English-speaking lower- and middle-class children aged 8 years in 2005 who had dyslexia, or were age-matched typically developing children, some with exceptional reading/high IQ. The predictive relations between auditory processing and phonological development are robust for this sample even when phonological awareness at Time 1 (the autoregressor) is controlled. High reading/IQ does not much impact these relations. The data suggest that basic sensory abilities are significant longitudinal predictors of growth in phonological awareness in children.
... There is extensive evidence that these developmental disorders are comorbid and that some children at family risk for dyslexia develop general oral deficits characteristic of developmental language disorder (Snowling & Melby-Lervag, 2016). In support of our preferred interpretation, we note that the word-learning difficulty reported in our AR group is consistent with previous effects of family risk of dyslexia on skill-related to lexical competence in our sample, including familiar word recognition (Kalashnikova, Goswami, & Burnham, 2019b) and auditory rise time discrimination . ...
Children of reading age diagnosed with dyslexia show deficits in reading and spelling skills, but early markers of later dyslexia are already present in infancy in auditory processing and phonological domains. Deficits in lexical development are not typically associated with dyslexia. Nevertheless, it is possible that early auditory/phonological deficits would have detrimental effects on the encoding and storage of novel lexical items. Word‐learning difficulties have been demonstrated in school‐aged dyslexic children using paired associate learning tasks, but earlier manifestations in infants who are at family risk for dyslexia have not been investigated. This study assessed novel word learning in 19‐month‐old infants at risk for dyslexia (by virtue of having one dyslexic parent) and infants not at risk for any developmental disorder. Infants completed a word‐learning task that required them to map two novel words to their corresponding novel referents. Not at‐risk infants showed increased looking time to the novel referents at test compared with at‐risk infants. These findings demonstrate, for the first time, that at‐risk infants show differences in novel word‐learning (fast‐mapping) tasks compared with not at‐risk infants. Our findings have implications for the development and consolidation of early lexical and phonological skills in infants at family risk of later dyslexia.
Cortical signals have been shown to track acoustic and linguistic properties of continual speech. This phenomenon has been measured across the lifespan, reflecting speech understanding as well as cognitive functions such as attention and prediction. Furthermore, atypical low-frequency cortical tracking of speech is found in children with phonological difficulties (developmental dyslexia). Accordingly, low-frequency cortical signals, especially in the delta and theta ranges, may play a critical role in language acquisition. A recent investigation Attaheri et al., 2022 (1) probed cortical tracking mechanisms in infants aged 4, 7 and 11 months as they listened to sung speech. Results from temporal response functions (TRF), phase-amplitude coupling (PAC) and dynamic theta-delta power (PSD) analyses indicated speech envelope tracking and stimulus related power (PSD) via the delta & theta neural signals. Furthermore, delta and theta driven PAC was found at all ages with gamma amplitudes displaying a stronger PAC to low frequency phases than beta. The present study tests whether those previous findings replicate in the second half of the same cohort (first half: N=61, (1); second half: N=61). In addition to demonstrating good replication, we investigate whether cortical tracking in the first year of life predicts later language acquisition for the full infant cohort (122 infants recruited, 113, retained). Increased delta cortical tracking and theta-gamma PAC were related to better language outcomes using both infant-led and parent-estimated measures. By contrast, increased ~4Hz PSD power and a greater theta/delta power ratio related to decreased parent-estimated language outcomes. The data are interpreted within a "Temporal Sampling" framework for developmental language trajectories.
In this handbook, the world's leading researchers answer fundamental questions about dyslexia and dyscalculia based on authoritative reviews of the scientific literature. It provides an overview from the basic science foundations to best practice in schooling and educational policy, covering research topics ranging from genes, environments, and cognition to prevention, intervention and educational practice. With clear explanations of scientific concepts, research methods, statistical models and technical terms within a cross-cultural perspective, this book will be a go-to reference for researchers, instructors, students, policymakers, educators, teachers, therapists, psychologists, physicians and those affected by learning difficulties.
The article focuses on the specificity of linguistic deficits in children with developmental language disorder (DLD) and/or specific reading learning disability (SRLD). A first objective is to present the current state of knowledge on the role of vocabulary in DLD and SRLD. This has a double impact: on the one hand, on written comprehension, on the other hand, on the procedures for identifying written words. A second objective is to suggest that certain differences observed between 234 children with DLD or SRLD stem from methodological choices. Thus, in studies on the SRLD, the level of vocabulary is a control variable, supposed not to differentiate the group of children with DLD from that of the typical readers, and the evaluations then relate most often to the procedure's identification of written words. On the other hand, it is the level of comprehension of oral language (from the word, to the sentence and to the text) that is at the center of studies on DLD. We can therefore think that vocabulary and written comprehension are relevant variables that should be taken into account in the understanding of these two disorders.
The amplitude envelope of speech carries crucial low-frequency acoustic information that assists linguistic decoding. The sensory-neural Temporal Sampling (TS) theory of developmental dyslexia proposes atypical encoding of speech envelope information <10 Hz, leading to atypical phonological representations. Here a backward linear TRF model and story listening were employed to estimate the speech information encoded in the electroencephalogram in the canonical delta, theta and alpha bands by 9-year-old children with and without dyslexia. TRF decoding accuracy provided an estimate of how faithfully the children's brains encoded low-frequency envelope information. Between-group analyses showed that the children with dyslexia exhibited impaired reconstruction of speech information in the delta band. However, when the quality of speech encoding for each child was estimated using child-by-child decoding models, then the dyslexic children did not differ from controls. This suggests that children with dyslexia encode neither "noisy" nor "normal" representations of the speech signal, but different representations.
Temporally accurate perception and production of rhythmic patterns are key factors related to language development and reading acquisition. Here we investigate rhythm discrimination and rhythm production in children who are at family risk or not at family risk for dyslexia, to compare group performance in these tasks prior to the start of reading instruction and to investigate the relation between individual children’s rhythmic abilities and pre-reading skills. Four-year-old children completed a rhythm discrimination task and a rhythm production task, both utilizing a temporal rate of 2 Hz, and also received pre-reading measures of non-word repetition, vocabulary, and letter knowledge. Controls outperformed at-risk children in the rhythm discrimination task and in the pre-reading measures. No group differences were observed in the rhythm production task, but individual differences in this task were related to scores of non-word repetition, vocabulary size, and letter knowledge. The data are discussed in terms of Temporal Sampling theory (Goswami, 2011).
We examined early vocabulary development in children at familial risk (FR) of dyslexia and typically developing (TD) children between 17 and 35 months of age. We trained a support vector machine to classify TD and FR using these vocabulary data at the individual level. The Dutch version of the McArthur-Bates Communicative Development Inventory (Words and Sentences) (N-CDI) was used to measure vocabulary development. We analyzed group-level differences for both total vocabulary as well as lexical classes: common nouns, predicates, and closed class words. The generalizability of the classification model was tested using cross-validation. At the group level, for both total vocabulary and the composites, the difference between TD and FR was most pronounced at 19–20 months, with FRs having lower scores. For the individual prediction, highest cross-validation accuracy (68%) was obtained at 19–20 months, with sensitivity (correctly classified FR) being 70% and specificity (correctly classified TD) being 67%. There is a sensitive window in which the difference between FR and TD is most evident. Machine learning methods are promising techniques for separating FR and TD children at an early age, before they start reading.
Purpose:
This study aimed to gain more insight into the relation between vocabulary and reading acquisition by examining early growth trajectories in the vocabulary of children at family risk (FR) of dyslexia longitudinally.
Method:
The sample included 212 children from the Dutch Dyslexia Program with and without an FR. Parents reported on their children's receptive and expressive vocabulary size at ages 17, 23, 29, and 35 months using the Dutch MacArthur Communicative Development Inventories. Dyslexia status at the end of Grade 2 (8 years) rendered 3 groups: FR-dyslexic (n = 51), FR-nondyslexic (n = 92), and typically developing-nondyslexic (TD) children (n = 69).
Results:
Repeated measures analyses showed that FR-dyslexic children had lower receptive vocabulary scores from 23 months onward and lower expressive scores from 17 months onward than FR-nondyslexic children. Latent growth curve modeling showed lower initial growth rates in FR-dyslexic children, followed by partial recovery, indicating a delayed increase in receptive and expressive vocabulary. FR-nondyslexic and TD children did not differ.
Conclusions:
Early deficits in receptive and expressive vocabulary are associated with later reading. Early vocabulary growth of FR-dyslexic children is characterized by a delay but not deviance of growth. Vocabulary can be considered an additional risk factor for dyslexia.
This article reviews 95 publications (based on 21 independent samples) that have examined children at family risk of reading disorders. We report that children at family risk of dyslexia experience delayed language development as infants and toddlers. In the preschool period, they have significant difficulties in phonological processes as well as with broader language skills and in acquiring the foundations of decoding skill (letter knowledge, phonological awareness and rapid automatized naming [RAN]). Findings are mixed with regard to auditory and visual perception: they do not appear subject to slow motor development, but lack of control for comorbidities confounds interpretation. Longitudinal studies of outcomes show that children at family risk who go on to fulfil criteria for dyslexia have more severe impairments in preschool language than those who are defined as normal readers, but the latter group do less well than controls. Similarly at school age, family risk of dyslexia is associated with significantly poor phonological awareness and literacy skills. Although there is no strong evidence that children at family risk are brought up in an environment that differs significantly from that of controls, their parents tend to have lower educational levels and read less frequently to themselves. Together, the findings suggest that a phonological processing deficit can be conceptualized as an endophenotype of dyslexia that increases the continuous risk of reading difficulties; in turn its impact may be moderated by protective factors. (PsycINFO Database Record
Speech perception in dyslexia is characterized by a categorical perception (CP) deficit, demonstrated by weaker discrimination of acoustic differences between phonemic categories in conjunction with better discrimination of acoustic differences within phonemic categories. We performed a meta-analysis of studies that examined the reliability of the CP deficit in dyslexia. The results show a reliable CP deficit in individuals with dyslexia compared to both chronological-age and reading-level controls. The CP deficit is stronger for discrimination than for identification, suggesting that the latter may only reveal between-category differences that do not fully reflect the CP deficit. The implications of these findings for the allophonic theory of dyslexia are discussed.
Recent years have seen the publication of a range of new theories suggesting that the basis of dyslexia might be sensory dysfunction. In this Opinion article, the evidence for and against several prominent sensory theories of dyslexia is closely scrutinized. Contrary to the causal claims being made, my analysis suggests that many proposed sensory deficits might result from the effects of reduced reading experience on the dyslexic brain. I therefore suggest that longitudinal studies of sensory processing, beginning in infancy, are required to successfully identify the neural basis of developmental dyslexia. Such studies could have a powerful impact on remediation.
Efficient language use involves the capacity to flexibly adjust to varied pronunciations of words. Although children can contend with some accent variability before their second birthday, it is currently unclear when and how this ability reaches its mature state. In a series of five experiments, we examine the developmental trajectory of toddlers’ comprehension of unfamiliar regional accents. Experiments 1 and 2 reveal that Canadian-English-learning 25-month-olds outperform their 20-month-old peers on the recognition of Australian-accented words and that this effect is likely driven by 25-month-olds’ larger vocabulary size. Experiments 3 to 5 subsequently show that 25-month-olds’ recognition of familiar words holds regardless of prior exposure to the speaker or accent. Taken together, these findings suggest that children’s ability to cope with accent variation improves substantially as their vocabulary expands in the second year of life and once it does, children recognize accented words on the fly, even without experience with the accent.
A rhythmic paradigm based on repetition of the syllable “ba” was used to study auditory, visual, and audio-visual oscillatory entrainment to speech in children with and without dyslexia using EEG. Children pressed a button whenever they identified a delay in the isochronous stimulus delivery (500 ms; 2 Hz delta band rate). Response power, strength of entrainment and preferred phase of entrainment in the delta and theta frequency bands were compared between groups. The quality of stimulus representation was also measured using cross-correlation of the stimulus envelope with the neural response. The data showed a significant group difference in the preferred phase of entrainment in the delta band in response to the auditory and audio-visual stimulus streams. A different preferred phase has significant implications for the quality of speech information that is encoded neurally, as it implies enhanced neuronal processing (phase alignment) at less informative temporal points in the incoming signal. Consistent with this possibility, the cross-correlogram analysis revealed superior stimulus representation by the control children, who showed a trend for larger peak r-values and significantly later lags in peak r-values compared to participants with dyslexia. Significant relationships between both peak r-values and peak lags were found with behavioral measures of reading. The data indicate that the auditory temporal reference frame for speech processing is atypical in developmental dyslexia, with low frequency (delta) oscillations entraining to a different phase of the rhythmic syllabic input. This would affect the quality of encoding of speech, and could underlie the cognitive impairments in phonological representation that are the behavioral hallmark of this developmental disorder across languages.
An on-going debate surrounds the relationship between specific language impairment and developmental dyslexia, in particular with respect to their phonological abilities. Are these distinct disorders? To what extent do they overlap? Which cognitive and linguistic profiles correspond to specific language impairment, dyslexia and comorbid cases? At least three different models have been proposed: the severity model, the additional deficit model and the component model. We address this issue by comparing children with specific language impairment only, those with dyslexia-only, those with specific language impairment and dyslexia and those with no impairment, using a broad test battery of language skills. We find that specific language impairment and dyslexia do not always co-occur, and that some children with specific language impairment do not have a phonological deficit. Using factor analysis, we find that language abilities across the four groups of children have at least three independent sources of variance: one for non-phonological language skills and two for distinct sets of phonological abilities (which we term phonological skills versus phonological representations). Furthermore, children with specific language impair-ment and dyslexia show partly distinct profiles of phonological deficit along these two dimensions. We conclude that a multiple-component model of language abilities best explains the relationship between specific language impairment and dyslexia and the different profiles of impairment that are observed.
In most of the world, people have regular exposure to multiple accents. Therefore, learning to quickly process accented speech is a prerequisite to successful communication. In this paper, we examine work on the perception of accented speech across the lifespan, from early infancy to late adulthood. Unfamiliar accents initially impair linguistic processing by infants, children, younger adults, and older adults, but listeners of all ages come to adapt to accented speech. Emergent research also goes beyond these perceptual abilities, by assessing links with production and the relative contributions of linguistic knowledge and general cognitive skills. We conclude by underlining points of convergence across ages, and the gaps left to face in future work.
Auditory cortical oscillations have been proposed to play an important role in speech perception. It is suggested that the brain may take temporal “samples” of information from the speech stream at different rates, phase resetting ongoing oscillations so that they are aligned with similar frequency bands in the input (“phase locking”). Information from these frequency bands is then bound together for speech perception. To date, there are no explorations of neural phase locking and entrainment to speech input in children. However, it is clear from studies of language acquisition that infants use both visual speech information and auditory speech information in learning. In order to study neural entrainment to speech in typically developing children, we use a rhythmic entrainment paradigm (underlying 2 Hz or delta rate) based on repetition of the syllable “ba,” presented in either the auditory modality alone, the visual modality alone, or as auditory-visual speech (via a “talking head”). To ensure attention to the task, children aged 13 years were asked to press a button as fast as possible when the “ba” stimulus violated the rhythm for each stream type. Rhythmic violation depended on delaying the occurrence of a “ba” in the isochronous stream. Neural entrainment was demonstrated for all stream types, and individual differences in standardized measures of language processing were related to auditory entrainment at the theta rate. Further, there was significant modulation of the preferred phase of auditory entrainment in the theta band when visual speech cues were present, indicating cross-modal phase resetting. The rhythmic entrainment paradigm developed here offers a method for exploring individual differences in oscillatory phase locking during development. In particular, a method for assessing neural entrainment and cross-modal phase resetting would be useful for exploring developmental learning difficulties thought to involve temporal sampling, such as dyslexia.
Over the past few years, there has been an increasing emphasis on studying the link between infant speech perception and later language acquisition. This research has yielded some seemingly contradictory findings: In some studies infants appear to use phonetic and indexical detail that they fail to use in other studies. In this article we present a new, unified framework for accounting for these divergent findings. PRIMIR (a developmental framework for Processing Rich Information from Multi-dimensional Interactive Representations) assumes there is rich information available in the speech input and that the child picks up and organizes this information along a number of multidimensional interactive planes. Use of this rich information depends on the joint activity of 3 dynamic filters. These filters—the initial biases, the develop-mental level of the child, and requirements of the specific language task the child is facing—work together to differentially direct attention to 1 (or more) plane. In this article we outline the contradictory data that need to be explained, elucidate PRIMIR, including its underlying assumptions and overall architecture, and compare it to ex-isting frameworks. We conclude by presenting core predictions of PRIMIR. Research on speech perception and word learning in infancy has produced a number of divergent findings that are difficult to reconcile within any of the existing models. In illustration of the complexity of the data generated, it has been known for some time that infants show categorical perception and treat variable instances of the same phonetic category as equivalent (for reviews, see Jusczyk, 1987; Werker, 1995). LANGUAGE LEARNING AND DEVELOPMENT, 1(2), 197–234 Copyright © 2005, Lawrence Erlbaum Associates, Inc.
A review of research that uses behavioral, electroencephalographic, and/or magnetoencephalographic methods to investigate auditory processing deficits in individuals with dyslexia is presented. Findings show that measures of frequency, rise time, and duration discrimination as well as amplitude modulation and frequency modulation detection were most often impaired in individuals with dyslexia. Less consistent findings were found for intensity and gap perception. Additional factors that mediate auditory processing deficits in individuals with dyslexia and their implications are discussed.
The core difficulty in developmental dyslexia across languages is a "phonological deficit", a specific difficulty with the neural representation of the sound structure of words. Recent data across languages suggest that this phonological deficit arises in part from inefficient auditory processing of the rate of change of the amplitude envelope at syllable onset (inefficient sensory processing of rise time). Rise time is a complex percept that also involves changes in duration and perceived intensity. Understanding the neural mechanisms that give rise to the phonological deficit in dyslexia is important for optimising educational interventions. In a three-deviant passive 'oddball' paradigm and a corresponding blocked 'deviant-alone' control condition we recorded ERPs to tones varying in rise time, duration and intensity in children with dyslexia and typically developing children longitudinally. We report here results from test Phases 1 and 2, when participants were aged 8-10 years. We found an MMN to duration, but not to rise time nor intensity deviants, at both time points for both groups. For rise time, duration and intensity we found group effects in both the Oddball and Blocked conditions. There was a slower fronto-central P1 response in the dyslexic group compared to controls. The amplitude of the P1 fronto-centrally to tones with slower rise times and lower intensity was smaller compared to tones with sharper rise times and higher intensity in the Oddball condition, for children with dyslexia only. The latency of this ERP component for all three stimuli was shorter on the right compared to the left hemisphere, only for the dyslexic group in the Blocked condition. Furthermore, we found decreased N1c amplitude to tones with slower rise times compared to tones with sharper rise times for children with dyslexia, only in the Oddball condition. Several other effects of stimulus type, age and laterality were also observed. Our data suggest that neuronal responses underlying some aspects of auditory sensory processing may be impaired in dyslexia.
The study concerns reading development and its precursors in a transparent orthography. Dutch children differing in family risk for dyslexia were followed from kindergarten through fifth grade. In fifth grade, at-risk dyslexic (n = 22), at-risk non-dyslexic (n = 45), and control children (n = 12) were distinguished. In kindergarten, the at-risk non-dyslexics performed better than the at-risk dyslexics, but worse than the controls on letter-knowledge and rapid naming. The groups did not differ on phonological awareness. At-risk dyslexics read less fluently from first grade onwards than the other groups. At-risk non-dyslexics' reading fluency was at an intermediate position between the other groups at the start of reading. By fifth grade they had reached a similar level as the controls on word reading, but still lagged behind on pseudoword reading. Results further showed that the parents of the groups of at-risk children differed in educational level and reading skills. Overall, the groups of at-risk children differed on pre-reading skills as well as on reading development. These differences do not seem to stem from differences in intellectual abilities or literacy environment. Instead, the better reading skills of parents of at-risk non-dyslexics suggest that these children might have a lower genetic liability.
Neural coding by brain oscillations is a major focus in neuroscience, with important implications for dyslexia research. Here, I argue that an oscillatory 'temporal sampling' framework enables diverse data from developmental dyslexia to be drawn into an integrated theoretical framework. The core deficit in dyslexia is phonological. Temporal sampling of speech by neuroelectric oscillations that encode incoming information at different frequencies could explain the perceptual and phonological difficulties with syllables, rhymes and phonemes found in individuals with dyslexia. A conceptual framework based on oscillations that entrain to sensory input also has implications for other sensory theories of dyslexia, offering opportunities for integrating a diverse and confusing experimental literature.
Developmental dyslexia is a multifaceted disorder of learning primarily manifested by difficulties in reading, spelling, and phonological processing. Neural studies suggest that phonological difficulties may reflect impairments in fundamental cortical oscillatory mechanisms. Here we examine cortical mechanisms in children (6-12 years of age) with or without dyslexia (utilising both age- and reading-level-matched controls) using electroencephalography (EEG). EEG data were recorded as participants listened to an audio-story. Novel electrophysiological measures of phonemic processing were derived by quantifying how well the EEG responses tracked phonetic features of speech. Our results provide, for the first time, evidence for impaired low-frequency cortical tracking to phonetic features during natural speech perception in dyslexia. Atypical phonological tracking was focused on the right hemisphere, and correlated with traditional psychometric measures of phonological skills used in diagnostic dyslexia assessments. Accordingly, the novel indices developed here may provide objective metrics to investigate language development and language impairment across languages.
Individual differences in ’phonological awareness’ or speech sound awareness between children predict reading and spelling development across languages, and children with dyslexia have impaired phonological awareness. Recent advances in our understanding of the neural basis of speech encoding suggest one possible sensory/neural basis for these individual differences. An oscillatory theoretical perspective is described, based on sampling of the speech stream by networks of cells that vary in excitability at different temporal rates. These variations in neural excitability (oscillations) may align to similar energy variations (such as amplitude modulations, AMs) in speech, helping to encode the signal. Indeed, cell networks in auditory cortex form an oscillatory hierarchy, which mirrors an AM hierarchy found in rhythmic speech. Mappings between these hierarchies may support parsing of the speech signal into phonological units. Oscillations at ~2 Hz may help identify stressed syllables, used to convey meaning in all languages, while oscillations at ~5 Hz may help identify syllables. Behavioural research suggests that the rhythmic patterning of stressed syllables may provide an acoustic ’skeleton’ or scaffold for phonological development across languages. As well as helping to explain individual differences, an oscillatory framework offers new targets for improving children’s phonological development, for example via multi-modal rhythmic activities.
Dyslexia is a neurodevelopmental disorder manifested in deficits in reading and spelling skills that is consistently associated with difficulties in phonological processing. Dyslexia is genetically transmitted, but its manifestation in a particular individual is thought to depend on the interaction of epigenetic and environmental factors. We adopt a novel interactional perspective on early linguistic environment and dyslexia by simultaneously studying two pre-existing factors, one maternal and one infant, that may contribute to these interactions; and two behaviours, one maternal and one infant, to index the effect of these factors. The maternal factor is whether mothers are themselves dyslexic or not (with/without dyslexia) and the infant factor is whether infants are at-/not-at family risk for dyslexia (due to their mother or father being dyslexic). The maternal behaviour is mothers' infant-directed speech (IDS), which typically involves vowel hyperarticulation, thought to benefit speech perception and language acquisition. The infant behaviour is auditory perception measured by infant sensitivity to amplitude envelope rise time, which has been found to be reduced in dyslexic children. Here, at-risk infants showed significantly poorer acoustic sensitivity than not-at-risk infants and mothers only hyperarticulated vowels to infants who were not at-risk for dyslexia. Mothers' own dyslexia status had no effect on IDS quality. Parental speech input is thus affected by infant risk status, with likely consequences for later linguistic development.
Visual-verbal paired associate learning (PAL) refers to the ability to establish an arbitrary association between a visual referent and an unfamiliar label. It is now established that this ability is impaired in children with dyslexia, but the source of this deficit is yet to be specified. This study assesses PAL performance in children with reading difficulties using a modified version of the PAL paradigm, comprising a comprehension and a production phase, to determine whether the PAL deficit lies in children's ability to establish and retain novel object-novel word associations or their ability to retrieve the learned novel labels for production. Results showed that while children with reading difficulties required significantly more trials to learn the object-word associations, when they were required to use these associations in a comprehension-referent selection task, their accuracy and speed did not differ from controls. Nevertheless, children with reading difficulties were significantly less successful when they were required to produce the learned novel labels in response to the visual stimuli. Thus, these results indicate that while children with reading difficulties are successful at establishing visual-verbal associations, they have a deficit in the verbal production component of PAL tasks, which may relate to a more general underlying impairment in auditory or phonological processing.
The direct influence of phonological awareness (PA) on reading outcomes has been widely demonstrated, yet PA may also exert indirect influence on reading outcomes through other cognitive variables such as morphological awareness (MA). However, PA's own development is dependent and influenced by many extraneous variables such as auditory processing, which could ultimately impact reading outcomes. In a group of pre-reading children with a family risk of dyslexia and low-risk controls, this study sets out to answer questions surrounding PA's relationship at various grain sizes (syllable, onset/rime and phoneme) with measures of auditory processing (frequency modulation (FM) and an amplitude rise-time task (RT)) and MA, independent of reading experience. Group analysis revealed significant differences between high- and low-risk children on measures of MA, and PA at all grain sizes, while a trend for lower RT thresholds of high-risk children was found compared with controls. Correlational analysis demonstrated that MA is related to the composite PA score and syllable awareness. Group differences on MA and PA were re-examined including PA and MA, respectively, as control variables. Results exposed PA as a relevant component of MA, independent of reading experience.
A continuing debate in language acquisition research is whether there are critical periods (CPs) in development during which the system is most responsive to environmental input. Recent advances in neurobiology provide a mechanistic explanation of CPs, with the balance between excitatory and inhibitory processes establishing the onset and molecular brakes establishing the offset of windows of plasticity. In this article, we review the literature on human speech perception development within the context of this CP model, highlighting research that reveals the interplay of maturational and experiential influences at key junctures in development and presenting paradigmatic examples testing CP models in human subjects. We conclude with a discussion of how a mechanistic understanding of CP processes changes the nature of the debate: The question no longer is, "Are there CPs?" but rather what processes open them, keeps them open, closes them, and allows them to be reopened. Expected final online publication date for the Annual Review of Psychology Volume 66 is November 30, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
By 12 months, children grasp that a phonetic change to a word can change its identity (phonological distinctive- ness). However, they must also grasp that some phonetic changes do not (phonological constancy). To test development of phonological constancy, sixteen 15-month-olds and sixteen 19-month-olds completed an eye-tracking task that tracked their gaze to named versus unnamed images for familiar words spoken in their native (Australian) and an unfamiliar non-native (Jamaican) regional accent of English. Both groups looked longer at named than unnamed images for Australian pronunciations, but only 19-month-olds did so for Jamaican pronunciations, indicating that phonological constancy emerges by 19 months. Vocabulary size pre- dicted 15-month-olds’ identifications for the Jamaican pronunciations, suggesting vocabulary growth is a via- ble predictor for phonological constancy development.
The study investigated cognitive deficits associated with dyslexia and familial risk of dyslexia (endophenotypes) by comparing children from families with and without a history of dyslexia. Eighty-eight school-aged children were assessed on measures of phonology, language and rapid automatized naming. A series of regression analyses with family risk and dyslexia status as predictors indicated that word recall, morphology, and rapid automatized naming were associated with the deficit, whereas the two phonological measures (phoneme awareness and nonword repetition) were associated with both literacy deficits and family risk, suggesting that the phonological deficit is an endophenotype of dyslexia. Whereas the association with familial risk was similar for the two phonological measures, they differed in their relation to dyslexia status: Phoneme awareness showed a stronger association with dyslexia than risk status, whereas nonword repetition was more strongly related to the risk. The data are interpreted within the framework of multiple deficit models of dyslexia.
Converging evidence suggests that developmental dyslexia is a neurobiological disorder, characterized by deficits in the auditory, visual, and linguistic domains. In the longitudinal project of the Dutch Dyslexia Programme, 180 children with a familial risk of dyslexia (FR) and a comparison group of 120 children without FR (noFR) were followed from the age of 2 months up to 9 years. Children were assessed on (1) auditory, speech, and visual event-related potentials every half year between 2 and 41 months; (2) expressive and receptive language, motor development, behaviour problems, and home-literacy environment by questionnaires at the age of 2 and 3; (3) speech–language and cognitive development from 47 months onwards; and (4) preliteracy and subskills of reading, and reading development during kindergarten and Grades 2 and 3.
Dyslexia is heritable and associated with phonological processing deficits that can be reflected in the event-related potentials (ERPs). Here, we recorded ERPs from 2-month-old infants at risk of dyslexia and from a control group to investigate whether their auditory system processes /bAk/ and /dAk/ changes differently. The speech sounds were presented in an oddball paradigm. The children were followed longitudinally and performed a word reading fluency test in second grade. The infant ERPs were subsequently analyzed according to high or low reading fluency in order to find a neurophysiological precursor of poor reading fluency. The results show that the fluent reading children (from both the at-risk and the control group) processed the speech sound changes differentially in infancy as indicated by a mismatch response (MMR). In the control group the MMR was frontally positive and in the fluent at-risk group the MMR was parietally positive. The non-fluent at-risk group did not show an MMR. We conclude that at-risk children who became fluent readers were better at speech processing in infancy than those who became non-fluent readers. This indicates a very early speech processing deficit in the group of later non-fluent readers.
Both subjective impressions and previous research with monolingual listeners suggest that a foreign accent interferes with word recognition in infants, young children, and adults. However, because being exposed to multiple accents is likely to be an everyday occurrence in many societies, it is unexpected that such non‐standard pronunciations would significantly impede language processing once the listener has experience with the relevant accent. Indeed, we report that 24‐month‐olds successfully accommodate an unfamiliar accent in rapid word learning after less than 2 minutes of accent exposure. These results underline the robustness of our speech perception mechanisms, which allow listeners to adapt even in the absence of extensive lexical knowledge and clear known‐word referents.
A video abstract of this article can be viewed at http: ⁄ ⁄www.youtube.com ⁄watch?v=bYnaZkMyKtY&feature=youtu.be
a b s t r a c t PRIMIR (Processing Rich Information from Multidimensional Interactive Representations; Curtin & Werker, 2007; Werker & Curtin, 2005) is a framework that encompasses the bidirectional relations between infant speech perception and the emergence of the lexicon. Here, we expand its mandate by considering infants growing up bilingual. We argue that, just like monolinguals, bilingual infants have access to rich information in the speech stream and by the end of their first year, they establish not only language-specific phonetic category representations, but also encode and represent both sub-phonetic and indexical detail. Perceptual biases, developmental level, and task demands work together to influence the level of detail used in any particular situation. In considering bilingual acquisition, we more fully elucidate what is meant by task demands, now understood both in terms of external demands imposed by the language situation, and internal demands imposed by the infant (e.g. different approaches to the same apparent task taken by infants from different backgrounds). In addition to the statistical learning mechanism previously described in PRIMIR, the necessity of a comparison–contrast mechanism is discussed. This refocusing of PRIMIR in the light of bilinguals more fully explicates the relationship between speech perception and word learning in all infants.
At 2 1/2 years of age, children who later developed reading disabilities were deficient in the length, syntactic complexity, and pronunciation accuracy of their spoken language, but not in lexical or speech discrimination skills. As 3-year-olds, these children began to show deficits in receptive vocabulary and object-naming abilities, and as 5-year-olds they exhibited weaknesses in object-naming, phonemic awareness, and letter-sound knowledge that have characterized kindergartners who became poor readers in other studies. These late preschool differences were related to subsequent reading status as well as to prior language skills, but early syntactic proficiency nevertheless accounted for some unique variance in grade 2 achievement when differences at age 5 were statistically controlled. The language deficits of dyslexic children were unrelated to maternal reading ability and were not observed in children from dyslexic families who became normal readers. The implications of the results for etiological issues are discussed.
Toward the end of their first year of life, infants’ overly specified word representations are thought to give way to more abstract ones, which helps them to better cope with variation not relevant to word identity (e.g., voice and affect). This developmental change may help infants process the ambient language more efficiently, thus enabling rapid gains in vocabulary growth. One particular kind of variability that infants must accommodate is that of dialectal accent, because most children will encounter speakers from different regions and backgrounds. In this study, we explored developmental changes in infants’ ability to recognize words in continuous speech by familiarizing them with words spoken by a speaker of their own region (North Midland-American English) or a different region (Southern Ontario Canadian English), and testing them with passages spoken by a speaker of the opposite dialectal accent. Our results demonstrate that 12- but not 9-month-olds readily recognize words in the face of dialectal variation.
In a 3-year longitudinal study, middle- to upper-middle-class preschool children at high family risk (HR group, N= 67) and low family risk (LR group, N= 57) for dyslexia (or reading disability, RD), were evaluated yearly from before kindergarten to the end of second grade. Both phonological processing and literacy skills were tested at each of four time points. Consistent with the well-known familiarity of RD, 34% of the HR group compared with 6% of the LR group became RD. Participants who became RD showed deficits in both implicit and explicit phonological processing skills at all four time points, clearly indicating a broader phonological deficit than is often found at older ages. The predictors of literacy skill did not vary by risk group. Both risk groups underwent a similar developmental shift from letter-name knowledge to phoneme awareness as the main predictor of later literacy skill. This shift, however, occurred 2 years later in the HR group. Familial risk was continuous rather than discrete because HR children who did not become RD performed worse than LR non-RD children on some phonological and literacy measures. Finally, later RD could be predicted with moderate accuracy at age 5 years, with the strongest predictor being letter-name knowledge.
This paper focuses on early lexical development, and especially the period around 18 months known as the vocabulary spurt. We first propose that this period corresponds to a shift from an associationist to a referential lexical acquisition mechanism following the developmental coupling of specific pre-linguistic and cognitive abilities. This latter mechanism would allow the acquisition of genuine words, i.e. links between phonetically specified sound patterns and object categories. We then review the literature on early lexical acquisition by typically developing infants and infants with Down and Williams syndrome, and report some data that were recently collected on this issue. We conclude that the data so far are congruent with our proposal, but because they remain insufficient, we propose some future research that focuses on the relation between pre-linguistic and cognitive developments.
Using a non-speech-specific measure of prosody, rise time perception, Goswami and her colleagues have found that individuals with dyslexia perform significantly worse than nonimpaired readers. Studies have also found that children and adults with specific language impairment were impaired on these tasks. Despite the high comorbidity of these disorders, only one study has assessed rise time sensitivity in children with comorbid reading and oral language difficulties. The authors further examined rise time sensitivity in children with both reading and oral language difficulties. They compared performance on rise time perception tasks between 18 children with reading difficulties, 15 children with combined reading and oral language difficulties, and 17 chronological age-matched controls. The authors found a significant interaction between group and performance on auditory tasks. Further tests revealed that chronological age-matched controls were significantly better on the rise time measures compared to both groups of children with reading difficulties. Performance between the groups of children with reading difficulties did not significantly differ.
It has been proposed that sensitivity to the parameters underlying speech rhythm may be important in setting up well-specified
phonological representations in the mental lexicon. However, different acoustic parameters may contribute differentially to
rhythm and stress in different languages. Here we contrast sensitivity to one such cue, amplitude envelope onset (rise time),
in dyslexic and normally-developing children in two languages, Hungarian and English, ages from 7 to 11. Dyslexic and control
children received phonological tasks, reading and spelling tasks and auditory processing tasks. While sensitivity to rise
time was related to phonological representation in both languages, clear differences were found between languages. It is suggested
that these differences may reflect differential language-specific weighting of different acoustic cues to rhythm and stress.
Children at risk for familial dyslexia (n=107) and their controls (n=93) have been followed from birth to school entry in the Jyväskylä Longitudinal study of Dyslexia (JLD) on developmental
factors linked to reading and dyslexia. At the point of school entry, the majority of the at-risk children displayed decoding
ability that fell at least 1 SD below the mean of the control group. Measures of speech processing were the earliest indices
to show both group differences in infancy and also significant predictive associations with reading acquisition. A number
of measures of language, including phonological and morphological skill collected repeatedly from age three, revealed group
differences and predictive correlations. Both the group differences and the predictive associations to later language and
reading ability strengthened as a function of increasing age. The predictions, however, tend to be stronger and the spectrum
of significant correlations wider in the at-risk group. These results are crucial to early identification and intervention
of dyslexia in at-risk children.
The aim of the present study was to investigate the effect of auditory training on voicing perception in French children with specific language impairment (SLI). We used an adaptive discrimination training that was centred across the French phonological boundary (0 ms voice onset time--VOT). One group of nine children with SLI attended eighteen twenty-minute training sessions with feedback, and a control group of nine children with SLI did not receive any training. Identification, discrimination and categorical perception were evaluated before, during and after training as well as one month following the final session. Phonological awareness and vocabulary were also assessed for both groups. The results showed that children with SLI experienced strong difficulties in the identification, discrimination and categorical perception of the voicing continuum prior to training. However, as early as after the first nine training sessions, their performance in the identification and discrimination tasks increased significantly. Moreover, phonological awareness scores improved during training, whereas vocabulary scores remained stable across sessions.
Acquiring a native language involves learning about its phonetic elements and the constraints on their ordering. Our study explored this issue by examining infants′ listening preferences for unfamiliar words that either observe or violate native language phonetic and phonotactic patterns. American 9-month-olds, but not 6-month-olds, listened significantly longer to words with English, rather than Dutch, sound patterns. Dutch 9-month-olds showed the opposite pattern of preferences. No preferences occurred for low-pass-filtered versions of the words, suggesting that infants were responding to phonetic and phonotactic properties rather than to prosodic ones. However, when words fundamentally differed in their prosodic organization (e.g., English vs Norwegian), even American 6-month-olds listened significantly longer to English words.
There is increasing evidence that during the latter half of their first year, infants begin learning about the organization of sound patterns in their native language. The present study investigated whether American infants are sensitive to the frequency with which certain phonetic patterns appear in English words. Two types of lists of monosyllables were presented using the headturn preference procedure. High-probability lists contained items with phonetic patterns that occur frequently in English words. Low-probability lists were composed of items with phonetic patterns that appear infrequently in English words. Nine-month-olds, but not 6-month-olds, listened significantly longer to the high-probability lists. A follow-up experiment indicated that the 9-month-olds′ preference for the high-probability lists occurs even when the lists are matched in terms of vowel quality. We discuss the implications of this preference for frequently appearing phonetic patterns for word recognition and the development of the mental lexicon.
It has recently been conjectured that dyslexia arises from abnormal auditory sampling. What sampling rate is altered and how it affects reading remains unclear. We hypothesized that by impairing phonemic parsing abnormal low-gamma sampling could yield phonemic representations of unusual format and disrupt phonological processing and verbal memory. Using magnetoencephalography and behavioral tests, we show in dyslexic subjects a reduced left-hemisphere bias for phonemic processing, reflected in less entrainment to ≈30 Hz acoustic modulations in left auditory cortex. This deficit correlates with measures of phonological processing and rapid naming. We further observed enhanced cortical entrainment at rates beyond 40 Hz in dyslexics and show that this particularity is associated with a verbal memory deficit. These data suggest that a single auditory anomaly, i.e., phonemic oversampling in left auditory cortex, accounts for three main facets of the linguistic deficit in dyslexia.
Across languages, children with developmental dyslexia have a specific difficulty with the neural representation of the sound structure (phonological structure) of speech. One likely cause of their difficulties with phonology is a perceptual difficulty in auditory temporal processing (Tallal, 1980). Tallal (1980) proposed that basic auditory processing of brief, rapidly successive acoustic changes is compromised in dyslexia, thereby affecting phonetic discrimination (e.g. discriminating /b/ from /d/) via impaired discrimination of formant transitions (rapid acoustic changes in frequency and intensity). However, an alternative auditory temporal hypothesis is that the basic auditory processing of the slower amplitude modulation cues in speech is compromised (Goswami et al., 2002). Here, we contrast children's perception of a synthetic speech contrast (ba/wa) when it is based on the speed of the rate of change of frequency information (formant transition duration) versus the speed of the rate of change of amplitude modulation (rise time). We show that children with dyslexia have excellent phonetic discrimination based on formant transition duration, but poor phonetic discrimination based on envelope cues. The results explain why phonetic discrimination may be allophonic in developmental dyslexia (Serniclaes et al., 2004), and suggest new avenues for the remediation of developmental dyslexia.
