Dissociating short-term memory and language impairment: The importance of item and serial order information

Background: Selective verbal short-term memory (STM) deficits are rare, and when they appear, they are often associated with a history of aphasia, raising doubts about the selectivity of these deficits. Recent models of STM consider that STM for item information depends on activation of the language system, and hence item STM deficits should be associated with language impairment. By contrast, STM for order information is considered to recruit a specific system, distinct from the language system: this system could be impaired in patients with language-independent STM deficits.

Aims: We demonstrate here the power of the item–order distinction to separate STM and language impairments in two brain-damaged cases with STM impairment and a history of aphasia.

Methods & Procedures: Recognition and recall STM tasks, maximising STM for either item or order information were administered to patients MB and CG.

Outcomes & Results: Patient MB showed mild phonological impairment. As predicted, associated STM deficits were characterised by poor item STM but preserved order STM. On the other hand, patient CG showed no residual language deficits. His STM deficit was characterised by poor order STM but perfectly preserved item STM.

Conclusions: This study presents the first double dissociation between item and order STM deficits, and demonstrates the necessity of this distinction for understanding and assessing STM impairment in patients with and without aphasia.     

Lexical spelling in children and adolescents with specific language impairment: Variations with the writing situation

The goal of this study was to compare the lexical spelling performance of children and adolescents with specific language impairment (SLI) in two contrasting writing situations: a dictation of isolated words (a classic evaluative situation) and a narrative of a personal event (a communicative situation). Twenty-four children with SLI and 48 typically developing children participated in the study, split into two age groups: 7–11 and 12–18 years of age. Although participants with SLI made more spelling errors per word than typically developing participants of the same chronological age, there was a smaller difference between the two groups in the narratives than in the dictations. Two of the findings are particularly noteworthy: (1) Between 12 and 18 years of age, in communicative narration, the number of spelling errors of the SLI group was not different from that of the typically developing group. (2) In communicative narration, the participants with SLI did not make specific spelling errors (phonologically unacceptable), contrary to what was shown in the dictation. From an educational perspective or that of a remediation program, it must be stressed that the communicative narration provides children—and especially adolescents—with SLI an opportunity to demonstrate their improved lexical spelling abilities. Furthermore, the results encourage long-term lexical spelling education, as adolescents with SLI continue to show improvement between 12 and 18 years of age.     

Assessment of second language proficiency in bilingual children with specific language impairment: a clinical perspective

The goal of this study was to examine to what extent the conditions of restricted input of L2 and SLI have an additive impact on language acquisition. Therefore, the Dutch language achievement of 6-, 7-, and 8-year-old bilingual children with SLI was compared with that of typically developing monolingual Dutch children, typically developing bilingual children, and monolingual Dutch children with SLI. Assuming that speaking a language in varying environments involves distinct subskills that can be acquired in differential patterns, the achievement of phonological, lexical, morphosyntactic and textual abilities were assessed separately. For each of these abilities, it was determined to what extent the conditions of restricted input (first vs. second language) and language deficit (typically developing vs. SLI) cause stagnation or a delay in language acquisition. Bilingual children with SLI perform at a lower level than the other groups in almost all aspects of achievement in Dutch. For language tasks related to the mental lexicon and grammar, an additional disadvantage was evidenced as a result of the combination of learning Dutch as second language and having SLI.     

The impact of lexical frequency on sentence comprehension in children with specific language impairment

Children with SLI generally exhibit poor sentence comprehension skills. We examined the specific impact of grammatical complexity and lexical frequency on comprehension performance, yielding contrasting results. The present study sheds new light on sentence comprehension in children with SLI by investigating a linguistic factor which has attracted little research interest: the impact of the lexical frequency of known words on sentence comprehension. We also examined the impact of grammatical complexity and sentence length by independently varying these two factors. Fifteen children with SLI, 15 age- and IQ-matched controls, and 15 controls matched on lexical and grammatical skills, performed sentence comprehension tasks in which three linguistic factors were manipulated: lexical frequency (sentences containing words of either low or high lexical frequency), grammatical complexity (sentence containing either a subject relative clause or an object relative clause) and sentence length (either short or long sentences). Results indicated that children with SLI performed more poorly overall compared to age- and IQ-matched children and to lexical and morphosyntactic age-matched children. However, their performance was not more affected by either sentence length or clause type than that of control children. Only lexical frequency affected sentence comprehension to a greater extent in children with SLI relative to the control groups, revealing that SLI children's sentence comprehension abilities are particularly affected by the presence of low-frequency but familiar words.     

Impaired short-term memory for order in adults with dyslexia

Verbal short-term memory (STM) deficits are consistently associated with dyslexia, but the nature of these deficits remains poorly understood. This study used the distinction between item and order retention processes to achieve a better understanding of STM deficits in adults with dyslexia. STM for item information has been shown to depend on the quality of underlying phonological representations, and hence should be impaired in dyslexia, which is characterized by poorly developed phonological representations. On the other hand, STM for order information is considered to reflect core STM processes, which are independent from language processing. Thirty adults with dyslexia and thirty control participants matched for age, education, vocabulary, and IQ were presented STM tasks, which distinguished item and order STM capacities. We observed not only impaired order STM in adults with dyslexia, but this impairment was independent of item STM impairment. This study shows that adults with dyslexia present a deficit in core verbal STM processes, a deficit which cannot be accounted for by the language processing difficulties that characterize dyslexia. Moreover, these results support recent theoretical accounts considering independent order STM and item STM processes, with a potentially causal involvement of order STM processes in reading acquisition.     

Comorbid motor deficits in a clinical sample of children with specific language impairment

The aim of the present study was to compare the motor function of a clinical sample of children with specific language impairment (SLI) to a language-matched comparison group that had not been referred for SLI assessment. A typical language comparison group with similar nonverbal IQ was also included. There were approximately 35 children in each group, aged 9- to 10-years-old, and the children completed a range of standardised language, motor and literacy measures. The results showed that the SLI group scored significantly lower than the language-matched and typical language comparison groups on all of the motor and literacy measures. We conclude that language factors alone are insufficient to explain the extensive comorbid motor and literacy deficits shown by the children with SLI in this study. We suggest that the clinical diagnosis of SLI may be influenced by the presence of additional developmental difficulties, which should be made explicit in assessment procedures, and that intervention strategies, which address the broad range of difficulties experienced by children with a clinical diagnosis of SLI, should be prioritised.     

Associations of HLA alleles with specific language impairment

Background

Human leukocyte antigen (HLA) loci have been implicated in several neurodevelopmental disorders in which language is affected. However, to date, no studies have investigated the possible involvement of HLA loci in specific language impairment (SLI), a disorder that is defined primarily upon unexpected language impairment. We report association analyses of single-nucleotide polymorphisms (SNPs) and HLA types in a cohort of individuals affected by language impairment.

Methods

We perform quantitative association analyses of three linguistic measures and case-control association analyses using both SNP data and imputed HLA types.

Results

Quantitative association analyses of imputed HLA types suggested a role for the HLA-A locus in susceptibility to SLI. HLA-A A1 was associated with a measure of short-term memory (P = 0.004) and A3 with expressive language ability (P = 0.006). Parent-of-origin effects were found between HLA-B B8 and HLA-DQA1*0501 and receptive language. These alleles have a negative correlation with receptive language ability when inherited from the mother (P = 0.021, P = 0.034, respectively) but are positively correlated with the same trait when paternally inherited (P = 0.013, P = 0.029, respectively). Finally, case control analyses using imputed HLA types indicated that the DR10 allele of HLA-DRB1 was more frequent in individuals with SLI than population controls (P = 0.004, relative risk = 2.575), as has been reported for individuals with attention deficit hyperactivity disorder (ADHD).

Conclusion

These preliminary data provide an intriguing link to those described by previous studies of other neurodevelopmental disorders and suggest a possible role for HLA loci in language disorders.     

Screening for pragmatic language impairment: The potential of the children's communication checklist

The present study examines the validity of the Dutch Children's Communication Checklist (CCC) for children in kindergarten in a community sample, in order to assess the feasibility of using it as a screening instrument in the general population. Teachers completed the CCC for a representative sample of 1396 children at kindergarten level, taken from 53 primary schools in The Netherlands. The CCC was also completed for a clinical group consisting of children with SLI in special education. Reliability as measured with internal consistency scores was found to be good for the community sample. With regard to the construct validity, a five-factor second-order factor model was found when the pragmatic subscales were analysed, which provided a reasonable fit. Criterion validity as measured using the concordance between the CCC and teacher opinions was moderate. The children identified by the CCC as having Pragmatic Language Impairment (defined as scoring below the cut off of 132) were often characterized by the teachers as having social–emotional problems, language problems or combined problems. Comparison with a clinical SLI sample showed the pragmatically impaired children in the community sample to have a profile similar to that of the clinical group of children with PLI in special education. The main difference was visible in structural language problems, which were less severe for the PLI group in mainstream education. The results of this study suggest that screening for PLI is indeed possible using the CCC.     

Social stress in young people with specific language impairment

Social interactions can be a source of social stress for adolescents. Little is known about how adolescents with developmental difficulties, such as specific language impairment (SLI), feel when interacting socially. Participants included 28 adolescents with SLI and 28 adolescents with typical language abilities (TL). Self-report measures of social stress, social skills and social acceptance were obtained. Participants with SLI reported experiencing significantly more social stress than did participants with TL. Both groups judged themselves as having adequate social skills and positive social acceptance. Expressive language ability was negatively associated with social stress, but did not predict social stress when social factors were included in the regression model. Perceived social skills and social acceptance scores predicted social stress, in that poorer scores predicted more social stress. Despite perceiving themselves as having adequate social skills and as being socially accepted, social interactions are nonetheless a source of stress for adolescents with SLI.     

Finite verb morphology and phonological length in the speech of children with specific language impairment

Children with specific language impairment (SLI) usually differ from younger peers in their use of grammatical morphemes pertaining to tense and agreement. The word‐final consonant status of many of these morphemes has prompted researchers to verify that the children under study are capable of producing these consonants in monomorphemic words (e.g. hand, box). However, such a measure does not ensure that the children with SLI are capable of producing words of sufficient length to support grammatical morpheme use. To examine the possible influence of this factor, we employed Ingram's phonological mean length of utterance (PMLU) as the basis for matching a group of preschoolers with SLI and younger typically developing peers. The children's use of tense/agreement morphemes was then determined. The findings indicated that despite the comparable PMLUs of the two groups, the children with SLI were more limited in their use of tense/agreement morphology than the younger peers.     

The role of short-term memory impairment in nonword repetition,real word repetition,and nonword decoding: A case study

In a companion study, adults with dyslexia and adults with a probable history of childhood apraxia of speech showed evidence of difficulty with processing sequential information during nonword repetition, multisyllabic real word repetition and nonword decoding. Results suggested that some errors arose in visual encoding during nonword reading, all levels of processing but especially short-term memory storage/retrieval during nonword repetition, and motor planning and programming during complex real word repetition. To further investigate the role of short-term memory, a participant with short-term memory impairment (MI) was recruited. MI was confirmed with poor performance during a sentence repetition and three nonword repetition tasks, all of which have a high short-term memory load, whereas typical performance was observed during tests of reading, spelling, and static verbal knowledge, all with low short-term memory loads. Experimental results show error-free performance during multisyllabic real word repetition but high counts of sequence errors, especially migrations and assimilations, during nonword repetition, supporting short-term memory as a locus of sequential processing deficit during nonword repetition. Results are also consistent with the hypothesis that during complex real word repetition, short-term memory is bypassed as the word is recognized and retrieved from long-term memory prior to producing the word.     

Analogical mapping across modalities in children with specific language impairment (SLI)

Analogical mapping is a domain-general cognitive process found in language development, and more particularly in the abstraction of construction schemas. Analogical mapping is considered as the general cognitive process which consists in the alignment of two or several sequences in order to detect their common relational structure and generalize it to new items. The current study investigated analogical mapping across modalities in children with specific language impairment (SLI). Nineteen children with SLI and their age-matched peers were administered two tasks: a linguistic analogical reasoning task (composed of syllables) and a similar non-linguistic analogical reasoning task (composed of pictures). In the two tasks, the items presented were divided into two groups: items with perceptual cues and items without perceptual cues. Children had to complete a sequence sharing the same relational structure as previously presented sequences. Results showed an expected group effect with poorer performance for children with SLI compared to children with typical language development (TLD). Results corroborate hypotheses suggesting that children with SLI have difficulties with analogical mapping, which may hinder the abstraction of construction schemas. Interestingly, whereas no interaction effect between group and modality (linguistic vs. non-linguistic) was revealed, a triple interaction Group * Modality * Perceptual support was observed. In the non-linguistic task, the performance of children with SLI was the same for items with and without perceptual clues, but in the linguistic task they performed more poorly for items without perceptual cues compared to items with perceptual cues. The results and limits of the study are discussed.     

The production of novel root compounds in children with specific language impairment

This study examined ten children with specific language impairment (SLI), 16 normally developing children, and ten adults for the production of novel root compounds. The participants were asked to invent names for pictures of 24 pairs of contrasting, novel objects. For half of the pictures, the context supported a grammatical novel root compound, 16 contexts supported only an ungrammatical compound, and eight contexts supported a marginally grammatical compound. All participants used novel root compounds in grammatical contexts and relatively few compounds in ungrammatical contexts. The children with SLI used the information presented in the experimental probes less frequently than the normal controls. In addition, the children with SLI made more word‐order errors in their production of novel compounds. However, they were as likely as their normal counterparts to resist the use of regular plural markers within compounds. The results of this study support a difficulty associated with processing linguistic information on the part of the children with SLI.     

Word and pseudoword reading in children with specific speech and language impairment

Children with specific language impairment frequently encounter difficulties in learning to read and in particular, in word recognition. The present study set out to determine the precise impact of language impairment on word reading skills. We investigated single-word reading in 27 French children with specific speech and language impairment (2SLI). Precise quantification of reading levels in the 2SLI group showed an average delay of 3.5 years. Approximately 90% of these children were affected by a reading disorder, whereas for the remaining 10%, reading performance was within normal limits. Word reading procedures are analyzed using the so-called ‘dual route model’, which proposes that reading is achieved through two processes, the phonological and the orthographic procedures. Group comparison analyses of 27 reading level-matched control children, revealed an increased lexicality effect in the 2SLI group, indicating a specific deficit in the phonological procedure. Moreover, multiple case analyses revealed interindividual differences among the children with 2SLI, with four reading subtypes. Approximately 60% of these children reached the standard levels expected of younger children with identical reading levels (delayed reading profile) in both procedures. Twenty percent displayed qualitatively different reading mechanisms, with a greater deficit in the phonological procedure (phonological profile). These children showed a severe impairment in language production at the phonological level. Ten percent exhibited a greater orthographic deficit (surface profile) and 10% had normal reading skills (normal profile). Further research is required to improve our understanding of the relationships between 2SLI or specific language impairment and reading acquisition. The present results suggest that in clinical practice, both reading procedures should be exercised, with emphasis on the phonological procedure for children with more severe deficits in phonological production.     

Memory consolidation in children with specific language impairment: Delayed gains and susceptibility to interference in implicit sequence learning

In this study, the time course of the procedural learning of a visuomotor sequence skill was followed over a 24-hour and a 1-week time period in children with and without specific language impairment (SLI). Two aspects of memory consolidation in implicit sequence learning were examined: the evolution of post-training gains in sequence knowledge (Experiment 1) and the susceptibility to interference (Experiment 2). In the first experiment, 18 children with SLI and 17 control children matched for sex, age, and nonverbal intelligence completed a serial reaction-time (SRT) task and were tested 24 hours and 1 week after practicing. The two groups of children attained an equal level of sequence knowledge in the training session, but the children with SLI lacked the consolidation gains displayed by the control children in the two post-training sessions. Working with a new group of children, 17 with SLI and 17 control peers, Experiment 2 examined resistance to interference by introducing a second sequence 15 min after the first training session. Similar results were obtained for the performance of both groups in the training session. However, although the performance of the control group improved in the post-training sessions, the performance of the SLI group deteriorated significantly during the consolidation phase due to the interfering sequence. These findings suggest that the consolidation phase of sequence learning is impaired in children with SLI.     

Syntactic comprehension and working memory in children with specific language impairment,autism or Down syndrome

This study examined syntactic assignment for predicates and reflexives as well as working memory effects in the sentence comprehension of children with Specific Language Impairment (SLI), Down syndrome (DS), high functioning Autism (HFA) and Typical Language Development (TLD). Fifty-seven children (35 boys and 22 girls) performed a computerised picture-selection sentence comprehension task. Predicate attachment and reflexive antecedent assignment (with working memory manipulations) were investigated. The results showed that SLI, HFA and DS children exhibited poorer overall performance than TLD children. Children with SLI exhibited similar performance to the DS and HFA children only when working memory demands were higher. We conclude that children with SLI, HFA and DS differ from children with TLD in their comprehension of predicate and reflexive structures where the knowledge of syntactic assignment is required. Working memory manipulation had different effects on syntactic comprehension depending on language disorder. Intelligence was not an explanatory factor for the differences observed in performance.     

Comprehension and production of noun compounds by Estonian children with specific language impairment

The authors examined how 12 Estonian‐speaking children with specific language impairment (SLI) and 60 children with normal speech development (ND) comprehended compound nouns with differing sequence of the components (first task) and how they produced compound nouns to label genuine and accidental categories by using analogy (second task) and sentence transformation (third task). The results demonstrated that children with SLI were capable of producing compound nouns for genuine categories, but avoided production of compounds to label objects in temporary juxtapositions. However, by comparison with the control group, SLI children differed statistically significantly in terms of both the number of correct answers and the pattern of mistakes. In the cases when compound nouns were expected to be produced by transforming sentences, the results of SLI children were considerably lower than those of their peers. The results of this study support the idea that children with SLI experience difficulties related to processing linguistic information.     

Analogical reasoning in children with specific language impairment

Usage-based theory considers analogical reasoning as a cognitive process required in language development. We hypothesized that difficulties with analogical reasoning could hinder the abstraction of construction schemas, thus slowing down morphosyntactic development for children with specific language impairment (SLI). We also hypothesized, in accordance with usage-based theory, that the same analogy mechanism is shared by linguistic and non-linguistic processes. The current study investigated the performance of 15 children with SLI in comparison with age-matched peers on a non-linguistic analogical reasoning task. Our experimental setting targeted two prerequisites of analogical reasoning: structural alignment and the discovery of relational similarity in comparison with perceptual similarity. The results obtained are compatible with our hypotheses according to which children with SLI would encounter problems building more abstract construction schemas, related to difficulties with analogical reasoning. The study also shows that children with SLI have specific cognitive difficulties regardless of their linguistic development.     

The sentence repetition task: A powerful diagnostic tool for French children with specific language impairment

This study assesses the diagnostic accuracy and construct validity of a sentence repetition task that is commonly used for the identification of French children with specific language impairment (SLI). Thirty-four school-aged children with a confirmed, diagnostically based diagnosis of SLI, and 34 control children matched on age and nonverbal abilities performed the sentence repetition task. Two general scoring measures took into account the verbatim repetition of the sentence and the number of words accurately repeated. Moreover, five other scoring measures were applied to their answers in order to separately take into account their respect of lexical items, functional items, syntax, verb morphology, and the general meaning of the sentence. Results show good to high levels of sensitivity and specificity at the three cut-off points for all scoring measures. A principal component analysis revealed two factors. Scoring measures for the respect of functional words, syntax and verb morphology provided the largest loadings to the first factor, while scoring measures for the respect of lexical words and general semantics provided the largest loadings to the second factor. Sentence repetition appears to be a valuable tool to identify SLI in French children, and the ability to repeat sentences correctly is supported by two factors: a morphosyntactic factor and a lexical factor.     

Phonotactic probability and past tense use by children with specific language impairment and their typically developing peers

A group of preschool‐aged children with specific language impairment (SLI), a group of typically developing children matched for age (TD‐A), and a group of younger typically developing children matched for mean length of utterance (TD‐MLU) were presented with novel verbs in contexts that required them to inflect with past tense –ed. The novel verbs differed in their phonotactic probabilities. The children with SLI were less likely than the other two groups to produce the novel verbs with –ed. Furthermore, they were less likely to use –ed with novel verbs of low phonotactic probability than those of high probability; this difference was not seen in the other two groups of children. It appears that the phonotactic composition of verbs is one factor that can contribute to the variability of past tense use by children with SLI.