Poor Nonword Repetition Research Articles

Probing Phonological Processing Differences in Nonword Repetition for Children with Separate or Co-Occurring Dyslexia and Developmental Language Disorder

ABSTRACT We assessed nonword repetition (NWR) skills in 7–9 year-old children with dyslexia (dyslexia-only), developmental language disorder (DLD-only), co-occurring DLD+dyslexia, and typical development (TD) with a norm-referenced and an experimental task. The experimental task manipulated phonemic variability (dissimilarity among consonant phonemes within the nonword) and presentation modality (audio-only versus audiovisual) to probe potential phonological processing differences among the groups. Across tasks, the dyslexia-only and DLD-only groups performed similarly to each other and intermediately to the TD and DLD+dyslexia groups. In the experimental task, nonwords with low phonemic variability were produced less accurately in both modalities, and audiovisual presentation facilitated accurate repetition of low phonemic variability nonwords. A lack of a group interaction with phonemic variability or presentation modality suggests similarities, despite group differences, in how underlying phonological representations influence task performance. Overall, results suggest that poor NWR is associated with both dyslexia and DLD, and that co-occurrence compounds this difficulty.

How to get by with half a loop – An investigation of visual and auditory codes in a case of impaired phonological short-term memory (pSTM)

In the field of cognitive neuropsychology of phonological short-term memory (pSTM), a key debate surrounds the issue of how impairment on tasks deemed to tap this system imply a dissociable phonological input and output buffer system, with the implication that impairments can be fractionated across disruption to separate functional components (Nickels, Howard & Best, 1997). This study presents CT, a conduction aphasic who showed no impairment on basic auditory discrimination tasks, but had very poor nonword repetition. Clear-cut examples of such cases are very rare (see Jacquemot, Dupoux & Bachoud-Levi, 2007), and we interpret the case with reference to a pSTM model that includes input and output buffers. The dissociation between performance on auditory phonological tasks and visual phonological tasks we interpret as consistent with disruption to the link from input buffer to output buffer without concurrent damage to connections from output to input. Previous research has also shown that patients with impairments of pSTM can make visual confusions with orthographically presented items in tasks seeking to tap this mechanism (Warrington & Shallice, 1972), which might stem from having an incomplete pSTM loop. In light of this we examined whether CT's ability on tests of ISR was affected by visual orthographic similarity among list items, and this is indeed what we observed. On balance then, CT's overall profile is considered best interpreted with respect to a dual buffer pSTM model (e.g., Vallar & Papagno, 2002).

The impact of attentional allocation capacities on nonword repetition in children with specific language impairment

This study aimed at directly assessing the hypothesis that attentional allocation capacity influences poor nonword repetition (NWR) performances in children with specific language impairment (SLI), using an attention demanding visual search task given concurrently with the NWR task. Twenty-one children with SLI, 21 typically developing children matched on age and 21 typically developing children matched on nonword span performed an immediate serial recall task of nonwords. The nonword lists were presented either alone or concurrently with the visual search task. Overall, results revealed a resource-sharing trade-off between the two tasks. Children with SLI were affected to the same extent as their span-matched controls by the necessity to allocate their attentional resources between the two tasks. Interestingly, nonword processing strategies seemed to differ among groups: age-matched controls allocated a larger part of their attentional resources to the encoding stage, whereas nonword recall was more attention demanding in children with SLI and younger controls.

Speech repetition as a window on the neurobiology of auditory–motor integration for speech: A voxel-based lesion symptom mapping study

For more than a century, speech repetition has been used as an assay for gauging the integrity of the auditory–motor pathway in aphasia, thought classically to involve a linkage between Wernicke's area and Broca's area via the arcuate fasciculus. During the last decade, evidence primarily from functional imaging in healthy individuals has refined this picture both computationally and anatomically, suggesting the existence of a cortical hub located at the parietal–temporal boundary (area Spt) that functions to integrate auditory and motor speech networks for both repetition and spontaneous speech production. While functional imaging research can pinpoint the regions activated in repetition/auditory–motor integration, lesion-based studies are needed to infer causal involvement. Previous lesion studies of repetition have yielded mixed results with respect to Spt's critical involvement in speech repetition. The present study used voxel-based lesion symptom mapping (VLSM) to investigate the neuroanatomy of repetition of both real words and non-words in a sample of 47 patients with focal left hemisphere brain damage. VLSMs identified a large voxel cluster spanning gray and white matter in the left temporal–parietal junction, including area Spt, where damage was significantly related to poor non-word repetition. Repetition of real words implicated a very similar dorsal network including area Spt. Cortical regions including Spt were implicated in repetition performance even when white matter damage was factored out. In addition, removing variance associated with speech perception abilities did not alter the overall lesion pattern for either task. Together with past functional imaging work, our results suggest that area Spt is integral in both word and non-word repetition, that its contribution is above and beyond that made by white matter pathways, and is not driven by perceptual processes alone. These findings are highly consistent with the claim that Spt is an area of sensory-motor translation in speech processing.

Lexical and Phonological Variability in Preschool Children With Speech Sound Disorder

The authors of this study examined relationships between measures of word and speech error variability and between these and other speech and language measures in preschool children with speech sound disorder (SSD). In this correlational study, 18 preschool children with SSD, age-appropriate receptive vocabulary, and normal oral motor functioning and hearing were assessed across 2 sessions. Experimental measures included word and speech error variability, receptive vocabulary, nonword repetition (NWR), and expressive language. Pearson product–moment correlation coefficients were calculated among the experimental measures. The correlation between word and speech error variability was slight and nonsignificant. The correlation between word variability and receptive vocabulary was moderate and negative, although nonsignificant. High word variability was associated with small receptive vocabularies. The correlations between speech error variability and NWR and between speech error variability and the mean length of children's utterances were moderate and negative, although both were nonsignificant. High speech error variability was associated with poor NWR and language scores. High word variability may reflect unstable lexical representations, whereas high speech error variability may reflect indistinct phonological representations. Preschool children with SSD who show abnormally high levels of different types of speech variability may require slightly different approaches to intervention.

Speech perception and phonological short‐term memory capacity in language impairment: preliminary evidence from adolescents with specific language impairment (SLI) and autism spectrum disorders (ASD)

The cognitive bases of language impairment in specific language impairment (SLI) and autism spectrum disorders (ASD) were investigated in a novel non-word comparison task which manipulated phonological short-term memory (PSTM) and speech perception, both implicated in poor non-word repetition. This study aimed to investigate the contributions of PSTM and speech perception in non-word processing and whether individuals with SLI and ASD plus language impairment (ALI) show similar or different patterns of deficit in these cognitive processes. Three groups of adolescents (aged 14-17 years), 14 with SLI, 16 with ALI, and 17 age and non-verbal IQ matched typically developing (TD) controls, made speeded discriminations between non-word pairs. Stimuli varied in PSTM load (two- or four-syllables) and speech perception load (mismatches on a word-initial or word-medial segment). Reaction times showed effects of both non-word length and mismatch position and these factors interacted: four-syllable and word-initial mismatch stimuli resulted in the slowest decisions. Individuals with language impairment showed the same pattern of performance as those with typical development in the reaction time data. A marginal interaction between group and item length was driven by the SLI and ALI groups being less accurate with long items than short ones, a difference not found in the TD group. Non-word discrimination suggests that there are similarities and differences between adolescents with SLI and ALI and their TD peers. Reaction times appear to be affected by increasing PSTM and speech perception loads in a similar way. However, there was some, albeit weaker, evidence that adolescents with SLI and ALI are less accurate than TD individuals, with both showing an effect of PSTM load. This may indicate, at some level, the processing substrate supporting both PSTM and speech perception is intact in adolescents with SLI and ALI, but also in both there may be impaired access to PSTM resources.

Atypical brain responses to sounds in children with specific language and reading impairments

This study tested if children with specific language impairment (SLI) or children with specific reading disability (SRD) have abnormal brain responses to sounds. We tested 6- to 12-year-old children with SLI (N =19), children with SRD (N =55), and age-matched controls (N =36) for their passive auditory event-related potentials (ERPs) to tones, rapid tones, vowels and consonant-vowels. Thirty-eight percent of the children with SLI or SRD had less typical passive auditory ERPs in the N1-P2 window to sounds in general, rather than to tones, rapid tones, vowels or consonant-vowels specifically. The ERPs of these children were significantly 'flatter' in the N1-P2 region than normal. All the children with flatter ERPs in the N1-P2 region had poor non-word reading. A subgroup of these poor non-word readers also had poor non-word repetition. These findings support the hypothesis that impaired auditory processing is a causal risk factor for both SLI and SRD.

A Nonword Repetition Task for Speakers With Misarticulations: The Syllable Repetition Task (SRT)

Conceptual and methodological confounds occur when non(sense) word repetition tasks are administered to speakers who do not have the target speech sounds in their phonetic inventories or who habitually misarticulate targeted speech sounds. In this article, the authors (a) describe a nonword repetition task, the Syllable Repetiton Task (SRT), that eliminates this confound and (b) report findings from 3 validity studies. Ninety-five preschool children with speech delay and 63 with typical speech completed an assessment battery that included the Nonword Repetition Task (NRT; C. Dollaghan & T. F. Campbell, 1998) and the SRT. SRT stimuli include only 4 of the earliest occurring consonants and 1 early occurring vowel. Study 1 findings indicated that the SRT eliminated the speech confound in nonword testing with speakers who misarticulate. Study 2 findings indicated that the accuracy of the SRT to identify expressive language impairment was comparable to findings for the NRT. Study 3 findings illustrated the SRT's potential to interrogate speech processing constraints underlying poor nonword repetition accuracy. Results supported both memorial and auditory-perceptual encoding constraints underlying nonword repetition errors in children with speech-language impairment. The SRT appears to be a psychometrically stable and substantively informative nonword repetition task for emerging genetic research and other research with speakers who misarticulate.

Comparing language profiles: children with specific language impairment and developmental coordination disorder

Although it is widely recognized that substantial heterogeneity exists in the cognitive profiles of children with Developmental Coordination Disorder (DCD), very little is known about the language skills of this group. To compare the language abilities of children with DCD with a group whose language impairment has been well described: children with Specific Language Impairment (SLI). Eleven children with DCD and 11 with SLI completed standardized and non-standardized assessments of vocabulary, grammatical skill, non-word repetition, sentence recall, story retelling, and articulation rate. Performance on the non-standardized measures was compared with a group of typically developing children of the same age. Children with DCD were impaired on tasks involving verbal recall and story retelling. Almost half of those in the DCD group performed similarly to the children with SLI over several expressive language measures, while 18% had deficits in non-word repetition and story retelling only. Poor non-word repetition was observed for both the DCD and the SLI groups. The articulation rate of the children with SLI was slower than that of the DCD group, which was slower than that of typically developing children. Language impairment is a common co-occurring condition in DCD. The language profile of children with either DCD or SLI was similar in the majority of, but not all, cases.

Further defining the language impairment of autism: Is there a specific language impairment subtype?

Some children with autism demonstrate poor nonword repetition—a deficit considered to be a psycholinguistic marker of specific language impairment (SLI). The present study examined whether there is an SLI subtype among children with autism. We compared the language abilities of children with SLI ( n = 34, M age = 11;10 S.D. = 2;3), and children with autism with (Apoor, n = 18, M age = 10;11 S.D. = 3;1) and without (Aapp, n = 16, M age = 10;8 S.D. = 2;7) structural language difficulties. Participants were administered battery of standardized language and memory tests. Although there were some similarities in the language profile of the SLI and Apoor groups, the two groups differed on the tests of oromotor ability and verbal short-term memory and showed a different pattern of errors on the nonword repetition task. These findings providing evidence against the idea of an SLI subtype in autism. Further analyses suggested that the nonword repetition deficits experienced by some children with autism may arise when there is substantial impairment in multiple autistic domains. Learning outcomes: Readers will be introduced to (a) the current state of behavioral, cognitive and genetic research that has investigated the relation between SLI and autism, and (b) three hypotheses of why there exists similarity in the language characteristics of children with SLI and autism. Readers will then be taken through a detailed comparison of the language and memory abilities of group of children with each diagnosis. A theoretical model that seeks to explain the relation between these two disorders will be discussed.

A methodological contribution to the assessment of nonword repetition—a comparison between children with specific language impairment and hearing-impaired children with hearing aids or cochlear implants

Poor nonword repetition is considered as a clinical marker of specific language impairment (SLI). In children with expressive language problems, the analysis and scoring procedures are often insufficiently described. We argue for a combined analysis of segmental and suprasegmental accuracy in nonword repetition tasks as well as an appreciation of gender differences. The view is taken based on empirical findings in a comparison between children with specific language impairment, children with mild/moderate hearing impairment and hearing aids (HI), and children with severe to profound hearing impairment with cochlear implants (CI). With age and gender taken into consideration, the main effects of both group and syllable level on a combined measure of segmental and suprasegmental accuracy remained. Although not necessarily an index of limited working memory capacity, persistently poor imitation of nonwords might be an indication of language impairment in children with mild/moderate HI and in children with CI.

Nonword repetition and language learning disorders: A developmental contingency framework

In 1990 Gathercole and Baddeley proposed a strong hypothesis that has generated a wealth of research in the field of language development and disorder. The hypothesis was that phonological memory, as indexed by nonword repetition, is causally related to vocabulary development. Support for the hypothesis came from an impressive range of longitudinal, correlational, and laboratory training studies, and from studies of specific language impairment (SLI). However, more recently, Gathercole, Tiffany, Briscoe, Thorn, and The ALSPAC Team (2005), directly tested the causal hypothesis by following a cohort of children from age 5 to 8 years. Contrary to prediction, children with poor nonword repetition abilities at age 5 had normal vocabulary at the age of 8.

Genetic Influences on Language Impairment and Literacy Problems in Children: Same or Different?

Data from two twin studies are examined to assess genetic and environmental influences on literacy, and the etiological relationship between language and literacy. Study 1 used children from 86 families previously recruited for a study of the genetics of specific language impairment (see Bishop, North, & Donlan, 1995), who completed tests of single-word reading and spelling. Literacy problems in this sample were common, were strongly heritable, and showed a close genetic relationship with poor nonword repetition. Study 2 included two subsets of children: 37 twin pairs who had taken part in study 1, 3 to 4 years earlier, and 100 twin pairs recruited from the general population by Bishop et al. (1999). All children were given a standardised test of nonword reading. There was no genetic influence on nonword reading ability, either across the normal range, or at the lower extreme, though there were significant associations with some social variables. However, bivariate DeFries Fulker analysis suggested that in this study, as in study 1, there was shared genetic variance between poor nonword repetition and literacy deficits. It is concluded that poor nonword repetition, which is known to be highly heritable, puts the child at risk for literacy problems. However, in a general population sample, such as that included in study 2, poor nonword repetition is a relatively rare correlate of literacy problems, which are more likely to have an environmental origin. Thus the different pattern of results in the two studies can be explained if one assumes that genetic influences are substantial only when literacy problems are severe and/or accompanied by oral language difficulties.

Limitations in working memory: implications for language development.

In this study, the proposal that individual differences in spoken language acquisition may be due to limitations in short-term memory abilities was investigated within a working memory framework. The relationship speech production skills and working memory abilities was examined in two groups of 4-year-old children, matched for non-verbal ability but who had either relatively good or poor non-word repetition skills. Children with better non-word repetition skills produced speech that comprised a wider repertoire of words, on average longer utterances and a greater range of syntactic constructions than did children with relatively poor non-word repetition skills. The significant association found between these indices of language development and verbal short-term memory span assessed with non-spoken recall, suggested that this relationship was not merely due to the common output requirements of the language and memory tasks. Inconsistent associations between language performance and two tasks of visuo-spatial short-term memory precluded firm conclusions being drawn regarding the specificity of the relationship to the phonological domain. Cognitive mechanisms that may underlie the association between spoken language development and working memory skills are discussed.