Beyond capacity limitations II: effects of lexical processes on word recall in verbal working memory tasks in children with and without specific language impairment

Moment-to-Moment Processing of Complex Sentences by Adults with and without Developmental Language Disorder

INTRODUCTION

. Limited evidence suggests that adults with developmental language disorder (DLD) take different information into account as they process sentences as compared to peers with typical language. The purpose of this study was to evaluate how two factors affect sentence processing in adults with DLD: online storage costs and lexical expectations created by nouns.

METHODS

. Forty-three adults, 21 with DLD, listened to complex sentences presented word-by-word, and their listening times were recorded. The sentences included either object relative clauses or sentential complements which differed in online storage demands. The main clause subject nouns differed in co-occurrence frequency with "that" in sentences produced by typical adults. Participants completed a running span task to assess verbal working memory capacity.

RESULTS

. Mixed effects models found differences by sentence region. Participants with DLD processed embedded clause verbs faster than participants with typical language, and poorer language ability was associated with faster processing of conjunctions "that" and "which." Participants with greater verbal working memory capacity or typical language were affected by noun co-occurrence frequencies but those with lower working memory or DLD were not.

CONCLUSIONS

. The results align with prior findings that verbal working memory capacity influences what information affects moment-to-moment sentence processing. Those with greater capacity appeared to be more affected by temporary ambiguity. As compared to adults with typical language, processing times of adults with DLD were less sensitive to information on words that frequently co-occur with nouns. This aligns with prior findings suggesting that adults with DLD are less sensitive to the frequency of the structures and arguments that co-occur with verbs.

A New Memory Perspective on the Sentence Comprehension Deficits of School-Age Children With Developmental Language Disorder: Implications for Theory, Assessment, and Intervention

Purpose The nature of the relationship between memory and sentence comprehension in school-age children with developmental language disorder (DLD) has been unclear. We present a novel perspective that highlights the relational influences of fluid intelligence, controlled attention, working memory (WM), and long-term memory (LTM) on sentence comprehension in children with and without DLD. This perspective has new and important implications for theory, assessment, and intervention. Method We review a large-scale study of children with and without DLD that focused on the connections between cognition, memory, and sentence comprehension. We also summarize a new model of these relationships. Results Our new model suggests that WM serves as a conduit through which syntactic knowledge in LTM, controlled attention, and general pattern recognition indirectly influence sentence comprehension in both children with DLD and typically developing children. For typically developing children, language-based LTM and fluid intelligence indirectly influence sentence comprehension. However, for children with DLD, controlled attention plays a larger indirect role. Conclusions WM plays a key role in children's ability to apply their syntactic knowledge when comprehending canonical and noncanonical sentences. Our new model has important implications for the assessment of sentence comprehension and for the treatment of larger sentence comprehension deficits.

Consistency of a Nonword Repetition Task to Discriminate Children with and without Developmental Language Disorder in Catalan-Spanish and European Portuguese Speaking Children

Nonword repetition has been proposed as a diagnostic marker of developmental language disorder (DLD); however, the inconsistency in the ability of nonword repetition tasks (NRT) to identify children with DLD raises significant questions regarding its feasibility as a clinical tool. Research suggests that some of the inconsistency across NRT may be due to differences in the nature of the nonword stimuli. In this study, we compared children's performance on NRT between two cohorts: the children in the Catalan-Spanish cohort (CS) were bilingual, and the children in the European Portuguese cohort (EP) were monolingual. NRT performance was assessed in both Spanish and Catalan for the bilingual children from Catalonia-Spain and in Portuguese for the monolingual children from Portugal. Results show that although the absolute performance differed across the two cohorts, with NRT performance being lower for the CS, in both Catalan and Spanish, as compared to the EP cohort in both, the cut-points for the likelihood ratios (LH) were similar across the three languages and mirror those previously reported in previous studies. However, the absolute LH ratio values for this study were higher than those reported in prior research due in part to differences in wordlikeness and frequency of the stimuli in the current study. Taken together, the findings from this study show that an NRT consisting of 3-, 4-, and 5-syllable nonwords, which varies in wordlikeness ratings, when presented in a random order accurately identifies and correctly differentiates children with DLD from TD controls the child is bilingual or monolingual.

The Effects of Frequency and Predictability on Repetition in Children With Developmental Language Disorder

Purpose Studies have shown that children with typical development (TD) respond to frequency and predictability when repeating nonidiomatic multiword sequences (e.g., go wash your hands). We extended these findings by explicitly examining the interaction between frequency and predictability in a repetition task for children with developmental language disorder (DLD) and children with TD. Method We created 48 four-word phrases, manipulating two factors: the frequency of occurrence of the entire four-word phrase (e.g., look in the mirror vs. look in the basket) and the predictability of the fourth word in the phrase given the preceding three words (e.g., corn on the ___ vs. look in the ___). These phrases were presented in a repetition task to 17 children with DLD (M _age = 58.89 months), 19 same-age children with TD (M _age = 59.79 months), and 17 younger children with TD matched to the DLD group on nonword repetition and mean length of utterance (M _age = 38.94 months). Children's repetitions were judged for the presence or absence of word and morphological errors. Only the first three words of the sequence were scored (e.g., look in the). Results We found a main effect of sequence frequency, with high-frequency sequences being repeated more accurately than low-frequency sequences, modulated by a significant interaction with predictability, where the effect of sequence frequency was larger for sequences with high-predictability contexts than for sequences with low-predictability contexts. We also found a significant effect of group, with children with DLD demonstrating poorer overall performance, particularly when compared to the same-age group with TD. Conclusions Frequency and predictability are strong predictors of language production in children with TD. These factors also have effects for children with DLD, raising important clinical questions about the design of facilitative contexts for the teaching of difficult linguistic forms.

Word Frequency Is Associated With Cognitive Effort During Verbal Working Memory: A Functional Near Infrared Spectroscopy (fNIRS) Study

PURPOSE

Psycholinguistic models traditionally view verbal working memory capacity as independent from linguistic features; connectionist models suggest otherwise. Moreover, lexical processing studies show high frequency words differ in cognitive effort from low frequency words, although these effects during concurrent processing of words in working memory are unknown. This novel study examines potential differences in cognitive effort, as measured by differences in HbO2 and Hb, for high frequency versus low frequency words during a working memory paradigm.

METHODS

A total of 21 neurologically typical participants (age 18-23) completed an auditory, n-back, working memory task comparing performance with high- as compared to low- frequency words. Hemodynamic changes in the prefrontal cortex were recorded with a continuous-wave functional near-infrared spectroscopy (fNIRS) device. Behavioral data (accuracy, reaction time) were recorded using E-prime.

RESULTS

Differences in word frequency were evident at both behavioral and neurological levels. Participants were more accurate, albeit slower in identifying the target two back in a sequence for low- as compared to high-frequency words. Patterns of hemodynamic changes were also significantly different between HF and LF conditions.

CONCLUSION

The results from this study indicate that the behavioral and neurological signatures inherent in holding high- versus low-frequency words in working memory differs significantly. Specifically, the findings from this study indicated that words differing in frequency place different demands on cognitive processing load in memory updating tasks.

The Effect of Working Memory Training on a Clinical Marker of French-Speaking Children With Developmental Language Disorder

Purpose Our work investigates the production of 3rd-person accusative clitic pronouns in French-speaking typically developing (TD) children and children with developmental language disorder (DLD) following a novel working memory (WM) training program (12 hrs of effective training) that specifically targets the components of WM that have been shown to be impaired in children with DLD and to be directly related to the mastery of clitics (Delage & Frauenfelder, submitted for publication; Durrleman & Delage, 2016). Method Sixteen TD children aged 5-12 years and 26 age-matched children with DLD completed our 8-week WM training program. Furthermore, an age-matched control group of 16 TD children and 17 children with DLD followed a scholastic training regime matched for intensity and frequency. Syntax and WM were assessed prior to and following the WM/scholastic training. Results Significant posttraining WM gains were found in TD children and children with DLD who took part in the WM training, and the production rate of 3rd-person accusative clitics significantly increased in children with DLD following the WM training. No significant WM or syntax gains were observed in the control group. Conclusion These findings are noteworthy as Melby-Lervåg and Hulme's (2013) meta-analysis concluded that existing WM training programs show short-lived generalized effects to other comparable measures of WM, but that there is no evidence that such training generalizes to less directly related tasks. That our study led to gains in skills that were not trained (i.e., syntax) suggests that a WM training regime that is firmly grounded in theory and that targets the specific mechanisms shown to underpin the acquisition of syntax may indeed provide effective remediation for children with DLD.

A Comparison of the Storage-Only Deficit and Joint Mechanism Deficit Hypotheses of the Verbal Working Memory Storage Capacity Limitation of Children With Developmental Language Disorder

Purpose The storage-only deficit and joint mechanism deficit hypotheses are 2 possible explanations of the verbal working memory (vWM) storage capacity limitation of school-age children with developmental language disorder (DLD). We assessed the merits of each hypothesis in a large group of children with DLD and a group of same-age typically developing (TD) children. Method Participants were 117 children with DLD and 117 propensity-matched TD children 7-11 years of age. Children completed tasks indexing vWM capacity, verbal short-term storage, sustained attention, attention switching, and lexical long-term memory (LTM). Results For the DLD group, all of the mechanisms jointly explained 26.5% of total variance. Storage accounted for the greatest portion (13.7%), followed by controlled attention (primarily sustained attention; 6.5%) and then lexical LTM (5.6%). For the TD group, all 3 mechanisms together explained 43.9% of total variance. Storage accounted for the most variance (19.6%), followed by lexical LTM (16.0%), sustained attention (5.4%), and attention switching (3.0%). There was a significant LTM × Group interaction, in which stronger LTM scores were associated with significantly higher vWM capacity scores for the TD group as compared to the DLD group. Conclusions Results support a joint mechanism deficit account of the vWM capacity limitation of children with DLD. Results provide substantively new insights into the underlying factors of the vWM capacity limitation in DLD. Supplemental Material https://doi.org/10.23641/asha.9932312.

Children and adolescents' performance on a medium-length/nonsemantic word-list test

Word-list learning tasks are among the most important and frequently used tests for declarative memory evaluation. For example, the California Verbal Learning Test-Children's Version (CVLT-C) and Rey Auditory Verbal Learning Test provide important information about different cognitive-neuropsychological processes. However, the impact of test length (i.e., number of words) and semantic organization (i.e., type of words) on children's and adolescents' memory performance remains to be clarified, especially during this developmental stage. To explore whether a medium-length non-semantically organized test can produce the typical curvilinear performance that semantically organized tests produce, reflecting executive control, we studied and compared the cognitive performance of normal children and adolescents by utilizing mathematical modeling. The model is based on the first-order system transfer function and has been successfully applied to learning curves for the CVLT-C (15 words, semantically organized paradigm). Results indicate that learning nine semantically unrelated words produces typical curvilinear (executive function) performance in children and younger adolescents and that performance could be effectively analyzed with the mathematical model. This indicates that the exponential increase (curvilinear performance) of correctly learned words does not solely depend on semantic and/or length features. This type of test controls semantic and length effects and may represent complementary tools for executive function evaluation in clinical populations in which semantic and/or length processing are affected.

Rethinking the connection between working memory and language impairment

BACKGROUND

Working memory deficits have been found for children with specific language impairment (SLI) on tasks imposing increasing short-term memory load with or without additional, consistent (and simple) processing load.

AIMS

To examine the processing function of working memory in children with low language (LL) by employing tasks imposing increasing processing loads with constant storage demands individually adjusted based on each participant's short-term memory capacity.

METHODS & PROCEDURES

School-age groups with LL (n = 17) and typical language with either average (n = 28) or above-average nonverbal intelligence (n = 15) completed complex working memory-span tasks varying processing load while keeping storage demands constant, varying storage demands while keeping processing load constant, simple storage-span tasks, and measures of language and nonverbal intelligence. Teachers completed questionnaires about cognition and learning.

OUTCOMES & RESULTS

Significantly lower scores were found for the LL than either matched group on storage-based tasks, but no group differences were found on the tasks varying processing load. Teachers' ratings of oral expression and mathematics abilities discriminated those who did or did not complete the most challenging cognitive tasks.

CONCLUSIONS & IMPLICATIONS

The results implicate a deficit in the phonological storage but not in the central executive component of working memory for children with LL. Teacher ratings may reveal personality traits related to perseverance of effort in cognitive research.

Lexical Processing in School-Age Children with Autism Spectrum Disorder and Children with Specific Language Impairment: The Role of Semantics

Children with autism spectrum disorder (ASD) and specific language impairment (SLI) often have immature lexical-semantic knowledge; however, the organization of lexical-semantic knowledge is poorly understood. This study examined lexical processing in school-age children with ASD, SLI, and typical development, who were matched on receptive vocabulary. Children completed a lexical decision task, involving words with high and low semantic network sizes and nonwords. Children also completed nonverbal updating and shifting tasks. Children responded more accurately to words from high than from low semantic networks; however, follow-up analyses identified weaker semantic network effects in the SLI group. Additionally, updating and shifting abilities predicted lexical processing, demonstrating similarity in the mechanisms which underlie semantic processing in children with ASD, SLI, and typical development.

Novel word learning: An eye-tracking study. Are 18-month-old late talkers really different from their typical peers?

Infants, 18-24 months old who have difficulty learning words compared to their peers are often referred to as "late talkers" (LTs). These children are at risk for continued language delays as they grow older. One critical question is how to best identify which LTs will have language disorders, such as Specific Language Impairment (SLI) at school age, in order to maximize the opportunity for early and appropriate intervention and support. Recent research suggests that LTs are not only slower to learn and speak words than their peers, but are also slower to recognize and interpret known words in real time. This investigation examined online moment-by-moment processing of novel word learning in 18-month-olds. A low vocabulary, late talking group (LT, N=14) and an age and cognitive-level matched typical group (TYP, N=14) of infants participated in an eye-tracked novel word learning task and completed standardized testing of vocabulary and cognitive ability. Infants were trained on two novel word-picture pairs and then were tested using an adaptation of the looking while listening paradigm. Results suggest that there are differences between groups in the time-course of looking to the novel target picture during testing. These findings suggest that LTs and typical infants developed strong enough representations to recognize novel words using traditional measures of accuracy and reaction time, however interesting group differences emerge when using additional fine-grained processing measures. Implications for differences in emerging knowledge and learning patterns are discussed.

LEARNING OUTCOMES

The reader will be able to understand many benefits of using eye-tracking methods to study young infant and toddler populations with and without language disorders. Readers will learn that examining moment-by-moment time course of novel word learning allows additional insight into different learning patterns. Finally, readers should understand the data from this article suggest late talkers may have different emerging representations of novel words than their typical peers, which may contribute to their difficulty learning new words.

Word recognition and nonword repetition in children with language disorders: the effects of neighborhood density, lexical frequency, and phonotactic probability

PURPOSE

The effects of neighborhood density (ND) and lexical frequency on word recognition and the effects of phonotactic probability (PP) on nonword repetition (NWR) were examined to gain insight into processing at the lexical and sublexical levels in typically developing (TD) children and children with developmental language problems.

METHOD

Tasks measuring NWR and word recognition were administered to 5 groups of children: 2 groups of TD children (5 and 8 years old), children with specific language impairment (SLI), children with reading impairment (RI), and children with SLI+RI (all 7-8 years old).

RESULTS

High ND had a negative effect on word recognition in the older TD children and in the children with RI only. There was no ND effect in the younger children or in the children with SLI, who all had lower receptive vocabulary scores than the age-matched TD children and the RI groups. For all groups, NWR items with low PP were more difficult to repeat than items with high PP. This effect was especially pronounced in children with RI.

CONCLUSION

Both the stage of vocabulary development and the type of language impairment (SLI or RI) impact the way ND and PP affect word recognition and NWR.

Sentence repetition: what does the task measure?

BACKGROUND

Sentence repetition is gaining increasing attention as a source of information about children's sentence-level abilities in clinical assessment, and as a clinical marker of specific language impairment. However, it is widely debated what the task is testing and therefore how informative it is.

AIMS

(1) To evaluate the effects of different types of long-term linguistic knowledge on immediate recall, (2) to assess age sensitivity of repetition tasks designed to evaluate these effects, and (3) to establish if the effects are similar across typologically different languages. The study also considers the implications of the findings for the use of sentence repetition as a research and clinical assessment tool.

METHODS & PROCEDURES

Participants were 50 English-speaking and 50 Czech-speaking typically developing 4-5-year-olds. Children's ability to recall sequences of items was compared in seven linguistic conditions ranging from fully well-formed sentences to sequences of non-words. In each condition, children repeated blocks of successively longer stimuli to establish their span.

OUTCOMES & RESULTS

Results showed significant but differential effects of all linguistic factors in both languages. While syntactic violations and presence of non-words dramatically reduced children's span, semantic implausibility and the removal of sentence prosody played a significant but much smaller role. Familiarity of function words was more important than familiarity of content words. The effects of different linguistic factors on spans were the same for both languages and did not change between 4 and 5 years, although average spans increased over this age range.

CONCLUSIONS & IMPLICATIONS

Children's ability to repeat sentences is more dependent on their familiarity with morphosyntax and lexical phonology than semantics or prosody, with function words of particular importance. Findings have implications for the use of recall in clinical assessment and as a research tool.

Language and verbal memory in individuals with a history of autism spectrum disorders who have achieved optimal outcomes

Some individuals who lose their autism spectrum disorder diagnosis may continue to display subtle weaknesses in language. We examined language and verbal memory in 44 individuals with high-functioning autism (HFA), 34 individuals with "optimal outcomes" (OO) and 34 individuals with typical development (TD). The OO group scored in the average range or above on all measures and showed few differences from the TD group. The HFA group performed within the average range but showed significantly lower mean performance than the other groups on multiple language measures, even when controlling for verbal IQ. Results also indicate that OO individuals show strong language abilities in all areas tested, but that their language may show greater reliance on verbal memory.

Computer-assisted training of phoneme-grapheme correspondence for children who are deaf and hard of hearing: effects on phonological processing skills

OBJECTIVE

Examine deaf and hard of hearing (DHH) children's phonological processing skills in relation to a reference group of children with normal hearing (NH) at two baselines pre intervention. Study the effects of computer-assisted phoneme-grapheme correspondence training in the children. Specifically analyze possible effects on DHH children's phonological processing skills.

METHODS

The study included 48 children who participated in a computer-assisted intervention study, which focuses on phoneme-grapheme correspondence. Children were 5, 6, and 7 years of age. There were 32 DHH children using cochlear implants (CI) or hearing aids (HA), or both in combination, and 16 children with NH. The study had a quasi-experimental design with three test occasions separated in time by four weeks; baseline 1 and 2 pre intervention, and 3 post intervention. Children performed tasks measuring lexical access, phonological processing, and letter knowledge. All children were asked to practice ten minutes per day at home supported by their parents.

RESULTS

NH children outperformed DHH children on the majority of tasks. All children improved their accuracy in phoneme-grapheme correspondence and output phonology as a function of the computer-assisted intervention. For the whole group of children, and specifically for children with CI, a lower initial phonological composite score was associated with a larger phonological change between baseline 2 and post intervention. Finally, 18 DHH children, whereof 11 children with CI, showed specific intervention effects on their phonological processing skills, and strong effect sizes for their improved accuracy of phoneme-grapheme correspondence.

CONCLUSION

For some DHH children phonological processing skills are boosted relatively more by phoneme-grapheme correspondence training. This reflects the reciprocal relationship between phonological change and exposure to and manipulations of letters.

Lexical activation during sentence comprehension in adolescents with history of Specific Language Impairment

One remarkable characteristic of speech comprehension in typically developing (TD) children and adults is the speed with which the listener can integrate information across multiple lexical items to anticipate upcoming referents. Although children with Specific Language Impairment (SLI) show lexical deficits (Sheng & McGregor, 2010) and slower speed of processing (Leonard et al., 2007), relatively little is known about how these deficits manifest in real-time sentence comprehension. In this study, we examine lexical activation in the comprehension of simple transitive sentences in adolescents with a history of SLI and age-matched, TD peers. Participants listened to sentences that consisted of the form, Article-Agent-Action-Article-Theme, (e.g., The pirate chases the ship) while viewing pictures of four objects that varied in their relationship to the Agent and Action of the sentence (e.g., Target, Agent-Related, Action-Related, and Unrelated). Adolescents with SLI were as fast as their TD peers to fixate on the sentence's final item (the Target) but differed in their post-action onset visual fixations to the Action-Related item. Additional exploratory analyses of the spatial distribution of their visual fixations revealed that the SLI group had a qualitatively different pattern of fixations to object images than did the control group. The findings indicate that adolescents with SLI integrate lexical information across words to anticipate likely or expected meanings with the same relative fluency and speed as do their TD peers. However, the failure of the SLI group to show increased fixations to Action-Related items after the onset of the action suggests lexical integration deficits that result in failure to consider alternate sentence interpretations.

LEARNING OUTCOMES

As a result of this paper, the reader will be able to describe several benefits of using eye-tracking methods to study populations with language disorders. They should also recognize several potential explanations for lexical deficits in SLI, including possible reduced speed of processing, and degraded lexical representations. Finally, they should recall the main outcomes of this study, including that adolescents with SLI show different timing and location of eye-fixations while interpreting sentences than their age-matched peers.

Rapid naming by children with and without specific language impairment

PURPOSE

Previous studies have reported that children with specific language impairment (SLI) name pictures more slowly than do chronological age-matched (CAM) peers. Rapid naming depends on 2 factors known to be problematic for children with SLI-lexical retrieval and nonlinguistic speed of processing. Although all studies implicate a speed-of-processing deficit as a contributing factor, researchers do not agree on the influence of language factors. The purpose of the current study was to explore word frequency (WF) and phonotactic pattern frequency (PPF) as potential lexical factors contributing to the naming deficits experienced by children with SLI.

METHOD

Three groups of children-20 children with SLI (Mage = 9;8 [years;months]), 20 younger vocabulary-matched (VM) controls, and 20 CAM controls-named pictures whose labels varied by WF and PPF.

RESULTS

Reaction time results revealed significant main effects of group (CAM < SLI = VM) and WF (high WF < low WF). Effects due to WF were comparable for all groups, but a significant Group × PPF interaction revealed that PPF effects were greater for children with SLI than for VM or CAM children.

CONCLUSION

Results replicate previous findings of a naming deficit in children with SLI. Furthermore, results suggest that children with SLI are more vulnerable to increased competition from words with frequent phonotactic patterns, which also come from dense phonological neighborhoods.

Phonological and lexical effects in verbal recall by children with specific language impairments

BACKGROUND & AIMS

The present study examined how phonological and lexical knowledge influences memory in children with specific language impairments (SLI). Previous work showed recall advantages for typical adults and children due to word frequency and phonotactic pattern frequency and a recall disadvantage due to phonological similarity among words. While children with SLI have well-documented memory difficulties, it is not clear whether these language knowledge factors also influence recall in this population.

METHODS & PROCEDURES

Sixteen children with SLI (mean age = 10;2) and chronological age-matched typically developing children (CAM) controls recalled lists of words differing in phonological similarity, word frequency and phonotactic pattern frequency. While previous studies used a small set of words appearing in multiple word lists, the current study used a larger set of words, without replacement, so that children could not gain practice with individual test items.

OUTCOMES & RESULTS

All main effects were significant. Interactions revealed that children with SLI were affected by similarity, but less so than their peers, comparably affected by word frequency and unaffected by phonotactic pattern frequency.

CONCLUSIONS & IMPLICATIONS

Results due to phonological similarity suggest that children with SLI use less efficient encoding, while results due to word frequency and phonotactic pattern frequency were mixed. Children with SLI used coarse-grained language knowledge (word frequency) comparably with peers, but were less able to use fine-grained knowledge (phonotactic pattern frequency). Paired with phonological similarity results, this suggests that children with SLI have difficulty establishing robust phonological knowledge for use in language tasks.

The impact of dual tasking on sentence comprehension in children with specific language impairment

PURPOSE

In this study, the authors assessed the hypothesis of a limitation in attentional allocation capacity as underlying poor sentence comprehension in children with specific language impairment (SLI).

METHOD

Fifteen children with SLI, 15 age-matched controls, and 15 grammar-matched controls participated in the study. Sixty sentences were presented in isolation, and 60 sentences were presented with a concurrent choice reaction time task in which colored stimuli randomly appeared at the center of the computer screen.

RESULTS

Sentence comprehension was affected by the dual-task condition to a greater extent in children with SLI relative to age controls but not relative to grammatical controls.

CONCLUSION

This study does not support limitations in attentional allocation capacity as representing a core deficit in SLI. Rather, the data show that these children show attentional allocation capacity comparable to that of younger children having similar language level, suggesting that SLI is characterized by a slowed development of both attentional and language domains.

Investigating sentence processing and language segmentation in explaining children's performance on a sentence-span task

BACKGROUND

Children with poor language abilities tend to perform poorly on verbal working memory tasks. This result has been interpreted as evidence that limitations in working memory capacity may interfere with the development of a mature linguistic system. However, it is possible that language abilities, such as the efficiency of sentence processing and the ability to segment language, directly influence performance on common working memory tasks.

AIMS

This study investigated the possible roles of sentence-processing efficiency and the ability to segment language in children's performance on a verbal working memory task.

METHODS & PROCEDURES

Participants were 37 children (aged 6;2-13;7) with varying oral language and reading abilities. Children completed a sentence-span task to assess working memory: the Competing Language Processing Task (CLPT). In the CLPT, children determine the truth value of sentences while maintaining sentence final words in memory. Sentence-processing efficiency was evaluated by measuring response latencies to CLPT sentence veracity judgments outside the context of the CLPT. The Elision and Blending Words subtests of the Comprehensive Test of Phonological Processing were used to measure the ability to segment and combine units of language.

OUTCOMES & RESULTS

Children's ability to segment words into smaller units (Elision) was a significant predictor of word recall on the CLPT, which is commonly assumed to reflect working memory capacity. Sentence processing latency did not reach significance as a unique predictor.

CONCLUSIONS & IMPLICATIONS

Individual differences on the sentence-span task are partly explained by the ability to segment language into smaller units. Future studies should further consider the metalinguistic and metacognitive demands of tasks used to measure working memory. If metalinguistic abilities directly impact performance on working memory tasks, the utility of working memory theories in explaining individual differences in language abilities is reduced. Inferences that link 'working memory capacity' to language ability become circular. One clinical implication of such a result would be that appropriate intervention strategies may not involve focusing on working memory capacity, but rather on building language skills, including metalinguistic knowledge, which in turn should directly improve children's processing capacities.

Explaining lexical-semantic deficits in specific language impairment: the role of phonological similarity, phonological working memory, and lexical competition

PURPOSE

In this study, the authors investigated potential explanations for sparse lexical-semantic representations in children with specific language impairment (SLI) and typically developing peers. The role of auditory perception, phonological working memory, and lexical competition were investigated.

METHOD

Participants included 32 children (ages 8;5-12;3 [years;months]): Sixteen children with SLI and 16 typically developing age- and nonverbal IQ-matched peers (CA). Children's word definitions were investigated. The words to be defined were manipulated for phonological neighborhood density. Nonword repetition and two lexical competition measures were tested as predictors of word definition abilities.

RESULTS

Children with SLI gave word definitions with fewer content details than children in the CA group. Compared with the CA group, the definitions of children in the SLI group were not disproportionately impacted by phonological neighborhood density. Lexical competition was a significant unique predictor of children's word definitions, but nonword repetition was not.

CONCLUSIONS

Individual differences in richness of lexical semantic representations as well as differences between children with SLI and typically developing peers may-at least, in part-be explained by processes of competition. However, difficulty with auditory perception or phonological working memory does not fully explain difficulties in lexical semantics.