Developmental Dyslexia Group Research Articles

Visual noise effect on reading in three developmental disorders: ASD, ADHD, and DD.

Developmental disorders such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD), and Developmental Dyslexia (DD) are reported to have more visual problems, oral language difficulties, and diminished reading skills in addition to their different diagnostic features. Moreover, these conditions also have increased internal noise and probably an impaired ability of external noise filtering. The aim of the present study was to compare the reading performance of these groups in the presence of external visual noise which disrupts the automatic reading processes through the degradation of letters. Sixty-four children and adolescents in four groups, ASD, ADHD, DD, and TD, participated in the study. Two types of stimuli were used - unrelated words and pseudowords. The noise was generated by exchanging a fixed number of pixels between the black symbols and the white background distorting the letters. The task of the participants was to read aloud the words or pseudowords. The reading time for a single letter string, word or pseudoword, was calculated, and the proportion of errors was assessed in order to describe the reading performance. The results obtained showed that the reading of unrelated words and pseudowords differs in the separate groups of participants and is affected differently by the added visual noise. In the no-noise condition, the group with TD had the shortest time for reading words and short pseudowords, followed by the group with ASD, while their reading of long pseudowords was slightly slower than that of the ASD group. The noise increase evoked variations in the reading of groups with ASD and ADHD, which differed from the no-noise condition and the control group with TD. The lowest proportion of errors was observed in readers with TD. The reading performance of the DD group was the worst at all noise levels, with the most prolonged reading time and the highest proportion of errors. At the highest noise level, the participants from all groups read the words and pseudowords with similar reading speed and accuracy. In reading words and pseudowords, the ASD, ADHD, and DD groups show difficulties specific for each disorder revealed in a prolonged reading time and a higher proportion of errors. The dissimilarity in reading abilities of the groups with different development is most evident when the accuracy and reading speed are linked together. The use of noise that degrades the letter structure in the present study allowed us to separate the groups with ASD, ADHD, and DD and disclose specifics in the reading process of each disorder. Error type analysis may provide a basis to improve the educational strategies by appropriately structuring the learning process of children with TD, ASD, ADHD, and DD.

Increased reliance on top-down information to compensate for reduced bottom-up use of acoustic cues in dyslexia

Speech recognition is a complex human behavior in the course of which listeners must integrate the detailed phonetic information present in the acoustic signal with their general linguistic knowledge. It is commonly assumed that this process occurs effortlessly for most people, but it is still unclear whether this also holds true in the case of developmental dyslexia (DD), a condition characterized by perceptual deficits. In the present study, we used a dual-task setting to test the assumption that speech recognition is effortful for people with DD. In particular, we tested the Ganong effect (i.e., lexical bias on phoneme identification) while participants performed a secondary task of either low or high cognitive demand. We presumed that reduced efficiency in perceptual processing in DD would manifest in greater modulation in the performance of primary task by cognitive load. Results revealed that this was indeed the case. We found a larger Ganong effect in the DD group under high than under low cognitive load, and this modulation was larger than it was for typically developed (TD) readers. Furthermore, phoneme categorization was less precise in the DD group than in the TD group. These findings suggest that individuals with DD show increased reliance on top-down lexically mediated perception processes, possibly as a compensatory mechanism for reduced efficiency in bottom-up use of acoustic cues. This indicates an imbalance between bottom-up and top-down processes in speech recognition of individuals with DD.

Orthographic depth and developmental dyslexia: a meta-analytic study

Cross-cultural studies have suggested that reading deficits in developmental dyslexia (DD) can be moderated by orthographic depth. To further explore this issue and assess the moderating role of orthographic depth in the developmental cognitive trajectories of dyslexic and typical readers, we systematically reviewed 113 studies on DD that were published from 2013 to 2018 and selected 79 in which participants received an official DD diagnosis. Each study was classified according to orthographic depth (deep vs. shallow) and participant age (children vs. adults). We assessed the difference between DD and control groups’ performance in reading tasks and in a wide range of cognitive domains associated with reading (phonological awareness (PA), rapid automatized naming (RAN), short-term working memory (WM), and nonverbal reasoning), including age and orthographies as moderators. We found an age-by-orthography interaction effect in word reading accuracy and a significant effect of age in pseudoword reading accuracy, but we found no effect of age and orthographic depth on the fluency parameters. These results suggest that reading speed is a reliable index for discriminating between DD and control groups across European orthographies from childhood to adulthood. A similar pattern of results emerged for PA, RAN, and short-term/WM. Our findings are discussed in relation to their impact on clinical practice while considering the orthographic depth and developmental level.

Failure of resting-state frontal–occipital connectivity in linking visual perception with reading fluency in Chinese children with developmental dyslexia

It is widely accepted that impairment in visual perception impedes children's reading development, and further studies have demonstrated significant enhancement in reading fluency after visual perceptual training. However, the mechanism of the neural linkage between visual perception and reading is unclear. The purpose of this study was to examine the intrinsic functional relationship between visual perception (indexed by the texture discrimination task,TDT) and reading ability (character reading and reading fluency) in Chinese children with developmental dyslexia (DD) and those with typical development (TD). The resting-state functional connectivity (RSFC) between the primary visual cortex (V1, BA17) and the entire brain was analyzed. In addition, how RSFC maps are associated with TDT performance and reading ability in the DD and TD groups was examined. The results demonstrated that the strength of the RSFC between V1 and the left middle frontal gyrus (LMFG, BA9/BA46) was significantly correlated with both the threshold (SOA) of the TDT and reading fluency in TD children but not in DD children. Moreover, LMFG-V1 resting-state connectivity played a mediating role in the association of visual texture discrimination and reading fluency, but not in character reading, in TD children. In contrast, this mediation was absent in DD children, albeit their strengths of RSFC between V1 and the left middle frontal gyrus (LMFG) were comparable to those for the TD group. These findings indicate that typically developing children use the linkage of the RSFC between the V1 and LMFG for visual perception skills, which in turn promote fluent reading; in contrast, children with dyslexia, who had higher TDT thresholds than TD children, could not take advantage of their frontal–occipital connectivity to improve reading fluency abilities. These findings suggest that visual perception plays an important role in reading skills and that children with developmental dyslexia lack the ability to use their frontal–occipital connectivity to link visual perception with reading fluency.

Intellectual characteristics of children with attention deficit hyperactivity disorder and developmental dyslexia

OBJECTIVE To study the intellectual characteristics of children with attention deficit hyperactivity disorder (ADHD) and developmental dyslexia (DD). METHODS A total of 55 children with ADHD and DD (ADHD+DD group), 150 children with ADHD alone (ADHD group), and 22 children with DD alone (DD group) were enrolled as subjects. Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) was used to evaluate and compare intellectual characteristics among the three groups. RESULTS There were significant differences in the scores of full-scale intelligence quotient (FSIQ), verbal comprehension index, perceptual reasoning index, and working memory index among the three groups (P < 0.05):the ADHD+DD group had significantly lower scores of FSIQ, verbal comprehension index, perceptual reasoning index, and working memory index than the ADHD group, as well as a significantly lower FSIQ score than the DD group. A comparison of the 10 core subtests in WISC-IV showed that compared with the ADHD group, the ADHD+DD group had significantly lower scores of similarities, vocabulary, comprehension, recitation, picture concepts, matrix reasoning, and letter-number sequencing (P < 0.05). Compared with the DD group, the ADHD+DD group had significantly lower scores of vocabulary, similarities, picture concepts, matrix reasoning, and recitation (P < 0.05). CONCLUSIONS Compared with the children with ADHD alone, the children with ADHD and DD have more severe impairment of FSIQ, verbal comprehension, perceptual reasoning, and working memory, and therefore, it is suggested to enhance the training on similarities, vocabulary, matrix reasoning, picture concepts, and recitation for children with ADHD and DD in clinical practice.

Alterations of procedural memory consolidation in children with developmental dyslexia.

[Correction Notice: An Erratum for this article was reported in Vol 35(2) of Neuropsychology (see record 2021-29488-002). In the article "Alterations of Procedural Memory Consolidation in Children With Developmental Dyslexia," by Martina Hedenius, Jarrad A. G. Lum, and Sven Bölte (Neuropsychology, 2021, Vol. 35, No. 2, pp. 185-196, https://doi.org/10.1037/neu0000708), three corrections have been made. The university affiliation for Martina Hedenius was listed incorrectly and should have read Uppsala University. The figures have been rearranged so that they appear in two-column format. In the Results section, the heading "Overnight Consolidation of Sequence Specific Knowledge" has been changed to "Consolidation of Sequence Specific Knowledge." All versions of this article have been corrected.] Objective: The objective of the present study was to determine if consolidation of procedural memory in developmental dyslexia (DD) may be supported by prolonging the initial learning session. Method: Children with DD (n = 31) and typically developing (TD) children (n = 34) were given a procedural (implicit sequence) learning task over two sessions, separated by a 24-hr interval. Session 1 was prolonged with 50% compared with previous studies of procedural memory consolidation in DD. Results: The amount of sequence learning was similar in the two groups at the end of Session 1 (p = .797, ηρ² = .001). At the follow-up session after 24 hr, performance in the DD group was poorer compared with the TD group (p = .003, ηρ² = .129). The amount of sequence knowledge in Session 2 predicted unique variance in reading fluency (p = .024, ηρ² = 0.083), independent of children's phoneme awareness and inattention symptoms. Conclusion: The present study shows that consolidation of procedural memory is impaired in DD, even when the initial learning session is prolonged. The findings encourage further research on the mechanisms supporting procedural memory consolidation in children with DD, and how these may be strengthened. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Alterations of procedural memory consolidation in children with developmental dyslexia. Correction to Hedenius et al. (2020).

Reports an error in "Alterations of procedural memory consolidation in children with developmental dyslexia" by Martina Hedenius, Jarrad A. G. Lum and Sven Bölte (Neuropsychology, Advanced Online Publication, Nov 19, 2020, np). In the article, three corrections have been made. The university affiliation for Martina Hedenius was listed incorrectly and should have read Uppsala University. The figures have been rearranged so that they appear in two-column format. In the Results section, the heading "Overnight Consolidation of Sequence Specific Knowledge" has been changed to "Consolidation of Sequence Specific Knowledge." All versions of this article have been corrected. (The following abstract of the original article appeared in record 2020-86309-001.) Objective: The objective of the present study was to determine if consolidation of procedural memory in developmental dyslexia (DD) may be supported by prolonging the initial learning session. Method: Children with DD (n = 31) and typically developing (TD) children (n = 34) were given a procedural (implicit sequence) learning task over two sessions, separated by a 24-hr interval. Session 1 was prolonged with 50% compared with previous studies of procedural memory consolidation in DD. Results: The amount of sequence learning was similar in the two groups at the end of Session 1 (p = .797, ηρ² = .001). At the follow-up session after 24 hr, performance in the DD group was poorer compared with the TD group (p = .003, ηρ² = .129). The amount of sequence knowledge in Session 2 predicted unique variance in reading fluency (p = .024, ηρ² = 0.083), independent of children's phoneme awareness and inattention symptoms. Conclusion: The present study shows that consolidation of procedural memory is impaired in DD, even when the initial learning session is prolonged. The findings encourage further research on the mechanisms supporting procedural memory consolidation in children with DD, and how these may be strengthened. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Magnocellular visual function in developmental dyslexia: deficit in frequency-doubling perimetry and ocular motor skills.

This study aimed to verify if patients with developmental dyslexia present deficits coherent with visual magnocellular dysfunction. Participants with confirmed diagnosis of developmental dyslexia (n=62; age range=8-25 years; mean age=13.8 years, standard deviation=3.9; 77% male) were compared to a control group with normal development, matched for age, sex, ocular dominance, visual acuity, and text comprehension. The frequency-doubling technology perimetry was used to evaluate the peripheral visual field contrast sensitivity threshold. The Visagraph III Eye-Movement Recording System was used to evaluate ocular motor skills during text reading. The developmental dyslexia group had significantly worse contrast sensitivity in the frequency-doubling technology, with strong effect size, than the matched control group. The developmental dyslexia group had more eyes classified in the impaired range of sensitivity threshold to detect frequency-doubling illusion than the control group. Moreover, the developmental dyslexia group had poorer ocular motor skills and reading performance, revealed by a difference in ocular fixations, regressions, span recognition, reading rate, and relative efficiency between groups. A significant correlation was found between contrast sensitivity and ocular motor skills. Participants with good relative efficiency had significantly better contrast sensitivity than participants with poor relative efficiency. The developmental dyslexia group presented a markedly worse performance in visual variables related to visual magnocellular function (i.e., frequency-doubling technology perimetry and ocular motor skills) compared with a matched control group. Professionals need to be aware of the importance of evaluating vision of individuals with developmental dyslexia beyond visual acuity and including in their assessments instruments to evaluate temporal processing, with contrast sensitivity threshold.

Sensory auditory interval perception errors in developmental dyslexia

Developmental dyslexia (DD) is a heritable condition associated with reading, visual and auditory deficits. Atypical processes involved in low-level sensory coding have been implicated. We tested the contribution made by auditory magnocellular function using a behavioural task which considered the temporal difference between pairs of identical sinewave tones. Adult undergraduates with an existing diagnosis of DD (n = 78) were compared with controls (n = 111) from the same population on error rates and response times at different interval durations. Error rates and response times increased in both groups with increasing task difficulty. However, on average the DD group made uniformly more errors and slower decisions than controls. Unsupervised learning of error patterns exposed a trait continuum associated with individual differences in response efficiency. Difficulty in using temporal information in DD arising from impaired sensory coding in the auditory thalamus is suggested. The results provide strong support for the idea that auditory processing difficulties in dyslexia, along with visual and sensorimotor deficits, have a common neurodevelopmental cause.

Behavior Problems and Depressive Symptoms in Developmental Dyslexia: Risk Assessment in Brazilian Students.

ObjectiveTo investigate if students with developmental dyslexia (DD) have more behavior problems and depressive symptoms than students without learning difficulties.MethodParticipants were 61 students, aged 7-14 years, including 31 with interdisciplinary DD diagnosis and 30 without learning disabilities. We collected data from parents, using the children’s behavior checklist (CBCL), and from students, using the children’s depression inventory (CDI).ResultsThe DD group had higher CBCL averages for anxiety, depression, withdrawal, rule-breaking behaviors, aggressiveness, and social, attentional and thought problems. They also showed higher results for the internalizing and externalizing categories, others and total. In the CDI, DD students had higher averages for total score and for the following symptoms: negative self-evaluation, guilt, suicidal thoughts, feeling concern, performance comparison, sleeping difficulties, fatigue, and problems in interacting with peers at school.ConclusionsWe discuss the results in terms of implications for DD diagnosis and intervention. Parent reports indicate a higher frequency of behavior problems in students with DD diagnosis. Those students also demonstrate more symptoms of depression than students without learning difficulties.

An Epidemiological Study of Chinese Children with Developmental Dyslexia.

The epidemiological studies of Chinese developmental dyslexia (DD) in China are still limited. The current study aimed to investigate the prevalence rate, risk factors, and psychiatric comorbidities of Chinese DD in Guangzhou, a city in South China. A total of 1661 students from second to fifth grades were recruited. The dyslexic students were identified by evaluating learning disability through the Pupil Rating Scale-Revised Screening for Learning Disability (PRS) scale by the head teachers and word recognition through the standard test. Students with a PRS score of <65 received the Raven's test, and those with intelligence quotient scores below 80 in the Raven's test were excluded. Psychiatric comorbidities were assessed by the Strength and Difficulties Questionnaire completed by parents. The prevalence rate of Chinese DD was 4.9% in Guangzhou city. There were significant differences in gender, the paternal educational level, and reading experience before the age of 6 years between the DD group and the non-DD group. Male gender (odds ratio [OR] = 4.17), low paternal educational level (p = 0.045), and lack of reading experience before the age of 6 years (OR = 1.99) were the risk factors for DD. The DD cases had a higher risk of hyperactivity and inattention (OR = 3.21). This study showed that the prevalence rate of DD was 4.9% in Guangzhou city. Male gender, low paternal educational level, and lack of reading experience before the age of 6 years were the risk factors for Chinese DD. The high comorbidity rate of hyperactivity and inattention in the Chinese DD population needs further evaluation.

The Clock Counts - Length Effects in English Dyslexic Readers.

In reading, length effects (LEs) are defined as an increment in the time taken to read as a function of word length and may indicate whether reading is proceeding in an efficient whole word fashion or by serial letter processing. LEs are generally considered to be a pathognomonic symptom of developmental dyslexia (DD) and predominantly have been investigated in transparent orthographies where reading impairment is characterized as slow and effortful. In the present study a sample of 18 adult participants with DD were compared to a matched sample of typical developing readers to investigate whether the LE is a critical aspect of DD in an opaque orthography, English. We expected that the DD group would present with marked LEs, in both words and non-words, compared to typical developing readers. The presence of LEs in the DD group confirmed our prediction. These effects were particularly strong in low frequency words and in non-words, as observed in reading speed. These preliminary findings may have important theoretical implications for current understanding of DD.

Writing Impairments in Spanish Children With Developmental Dyslexia

This study investigated which components of the writing production process are impaired in Spanish children with developmental dyslexia (DD) aged 8 to 12 years. Children with and without dyslexia (n = 60) were assessed in their use of the lexical and the sublexical routes of spelling as well as the orthographic working memory system by manipulating lexical frequency, phonology-to-orthography (P-O) consistency, and word length in a copying task and a spelling-to-dictation task. Results revealed that children with dyslexia produced longer written latencies than chronological age-matched (CA) controls, more errors than CA and reading age-matched (RA) controls, and writing durations similar to CA controls. Latencies were more affected by frequency, consistency, and length in the DD group and the RA group than in CA controls. Children in the DD and RA groups produced longer written latencies in the copying than in the spelling-to-dictation task, while controls in the CA group were not affected by the task. Results indicate that spelling impairments in Spanish children with dyslexia affect the relative involvement of lexical and sublexical information during handwriting. Meanwhile, effects on writing speed seem to be related to deficits in reading ability, and accuracy scores seem to be poorer than expected by children’s reading skill.

Visual processing speed as a marker of immaturity in lexical but not sublexical dyslexia

A visual attention span (VAS) deficit has been widely reported in the Developmental Dyslexia (DD) literature, however, consensus regarding what underlies this problem and the nature of its relationship with reading ability remains elusive. Thirty-two children with DD (15 females) were compared with 23 age matched (12 females) and 17 reading matched controls (9 females) on the combined Theory of Visual Attention (CombiTVA) paradigm with traditional letter and novel symbol conditions. The DD group performed more slowly than the age matched controls in terms of processing speed, but similarly to reading matched controls. Moderation analyses revealed that the difference between the DD group and age matched controls was driven by children with equivalent, or relatively poorer, lexical compared with sublexical reading profiles. Results suggest that reduced processing speed indexes reading immaturity, particularly in DD individuals with relative lexical reading deficits, rather than being a unique contributor to reading dysfunction.

The Effects of Font Type on Reading Accuracy and Fluency in Japanese Children with Developmental Dyslexia

We administered rapid reading tasks in Japanese children (32 with typical development and 24 with developmental dyslexia), and investigated the effects of two different font types: Rounded-Gothic and Mincho style font. In the experiment, we used four kinds of stimuli: two scripts (paragraphs and random kana character non-words) in two font types (Rounded-Gothic and Mincho style font). In this experiment, the duration time, the number of errors and the number of self-corrections were measured during reading. Participants were asked which font type was easier to read. There was no significant difference in the duration time, the number of errors and the number of self-corrections between two types of fonts among the 56 participants. On the other hand, regarding subjective readability, the developmental dyslexia group reported that the Rounded-Gothic font was easier to read. There was a difference between objective and subjective readability. In this study, there was no difference in reading performance of Rounded-Gothic and Mincho style fonts in Japanese children with developmental dyslexia.

When prosody meets syntax: The processing of the syntax-prosody interface in children with developmental dyslexia and developmental language disorder

Prosody and syntax are assumed to interact strictly, both in terms of processing and of brain activation. According to some authors, the interaction between prosody and other components of language such as syntax and pragmatics would be problematic for children with DLD and/or dyslexia, whereas prosody itself would not. Sixteen children with typical development (TD), 16 children with developmental dyslexia (DD) and 16 with Developmental Language Disorder (DLD) aged 10–13 took part in the experiment. Children had to perform a picture matching task, after listening to sentences with an ambiguous syntactic structure disambiguated through prosody. A GLM analysis was performed taking into account the number of pictures representing target responses, distractors or alternative interpretations. Correlations with tests of language and reading were also computed. Participants with DLD chose distractors more often than participants with DD and TD in correspondence to sentences with complex psycholinguistic structure. Children with DLD gave less target responses than children with DD but their response pattern was similar to that of TD children, whereas the DD group showed a qualitatively different profile. Strong correlations emerged between the capacity to process the syntax-prosody interface and metaphonological as well as morphosyntactic abilities.

Self-reported visual symptoms in children with developmental dyslexia

Although there are many anecdotal reports of children with developmental dyslexia complaining of vision symptoms when reading, empirical studies are lacking. The primary aim of the present study was to document self-reported vision-related symptoms in children with developmental dyslexia and typically reading peers. We also explored whether vision symptoms were correlated with sensorimotor measures of vergence, accommodation and ocular motor tracking skills. Using a prospective group comparison observational design, we assessed 28 children with developmental dyslexia (DD) and 33 typically reading children (TR) 7–11 years of age. Participants completed psychoeducational testing, a comprehensive sensorimotor eye examination, and the Convergence Insufficiency Symptom Survey (CISS), which includes 9 items pertaining to vision-related symptoms (CISS-V) and 6 that could have cognitive influence (CISS-C). CISS-V were significantly greater in DD than TR children. Ocular motor tracking, assessed by an infra-red limbal eye tracker while reading text, was most clearly associated with the visual symptoms, but only within the DD group. Vision-related symptom surveys followed by a comprehensive eye examination with detailed evaluation of sensorimotor functioning for those who report a high prevalence of symptoms may be clinically relevant for children with DD.

Brain Mechanisms Underlying Visuo-Orthographic Deficits in Children With Developmental Dyslexia.

Multiple hypotheses have been proposed to explain the reading difficulty caused by developmental dyslexia (DD). The current study examined visuo-orthographic processing in children with dyslexia to determine whether orthographic deficits are explainable based solely on visual deficits. To identify orthographic-specific, visual perception-specific, and overlapping deficits, we included two tasks (lexical and perceptual) in three Chinese subject groups: children with DD, age-matched controls (AC), and reading matched controls (RC) using functional magnetic resonance imaging (fMRI). We found that the left precuneus showed decreased activation across both tasks for the DD group compared to the two control groups, thus reflecting visual processing deficits in children with DD, which also affects orthographic processing. Furthermore, we found that the functional connectivity between left middle occipital gyrus (LMOG) and left inferior frontal gyrus (IFG) was decreased in the DD group compared to AC and RC for only the lexical task. This suggests a weaker association between orthography and phonology for children with DD. In addition, the children with DD showed decreased functional connectivity between the LMOG and right parahippocampal gyrus for only the visual perceptual task, thereby indicating a weaker association between visual regions for DD during visual symbol processing. Taken together, our findings suggest that the observed orthographic processing deficit in DD might be driven by both a basic visual deficit, and a linguistic deficit.

Verbal fluency in relation to reading ability in students with and without dyslexia

ABSTRACTVerbal fluency tasks, in which participants generate words during a set time, have been used in research and assessments of neurobiological disorders and impairments. Research on verbal fluency in dyslexia has shown impaired performance in semantic and letter fluency. However, studies report inconsistent results, and action fluency has not been examined in dyslexia. Current research has mainly examined verbal fluency in relation to executive functions, vocabulary, and phonological processing. The present study examined performance on letter, semantic, and action fluency in relation to reading ability in 42 students in higher education, of which 16 had developmental dyslexia and 26 had typical reading development. It was examined if verbal fluency can predict variance in reading ability when group, phonological awareness, and rapid automatized naming are controlled for. Results showed impaired verbal fluency in the developmental dyslexia group. Action fluency and group were significant predictors of reading ability, together explaining 73% of the variance, in a backward elimination regression analysis. The results point to a possible, unique connection between action fluency and reading ability; this connection is discussed based on their neurocognitive underpinnings.

Learning to decipher time-compressed speech: Robust acquisition with a slight difficulty in generalization among young adults with developmental dyslexia.

Learning to decipher acoustically distorted speech serves as a test case for the study of language-related skill acquisition in persons with developmental dyslexia (DD). Deciphering this type of input is rarely learned explicitly and does not yield conscious insights. Problems in implicit and procedural skill learning have been proposed as possible causes of DD. Here we examined the learning of time-compressed (accelerated) speech and its generalization to novel materials among young adults with DD compared to typical readers (TD). All participants completed a training session that involved judging the semantic plausibility of sentences, during which the level of time-compression was changed using an adaptive (staircase) procedure according to each participant’s performance. In the test, phase learning (test on same items) and generalization (test on new items and same items spoken by a new speaker) were assessed. Both groups showed robust gains after training. Moreover, after training, the initial disadvantage of the DD group was no longer significant. After training, both groups experienced relative difficulties in deciphering learned tokens spoken by a different voice, though participants with DD were less able to generalize the gains to deciphering new tokens. Thus, DD individuals benefited from repeated experience with time-compressed speech no less than typical readers, but their evolving skill was apparently more dependent on the specific characteristics of the tokens. Atypical generalization, which indicates that perceptual learning is contingent on lower-level features of the input though does not necessarily point to impaired learning potential per se, may explain some of the contradictory findings in published studies of speech perception in DD.