Language properties and executive functions in the identification of SLI children in monolingual and bilingual populations

One of the crucial topics in language disorders is finding markers to identify SLI children in the early stages. It’s been found in several studies that children with SLI perform worse than typically developing children on measures of attention and working memory (Bishop 1997, Tallal 2000, van der Lely & Howard 1993).The main concern of this special issue is to supply tools to identify SLI children. To reach this goal, we present a series of articles that help to differentiate SLI children from other impairments, like autism, deafness, and Williams Syndrome. We also include articles that supply tools to help diagnose children with SLI: These studies deal with sentence repetition, nonword repetition, working memory, and language properties. In addition, we include articles that try to distinguish the symptoms of SLI children with respect to bilingual children, which seem to be similar in some respects. We try to cover new interests in this field, which include bilingual populations and executive functions. Identification of children with SLI can be done by exclusion, when there is a delay in the development language properties, but you can find articles on pragmatic disorders (Jeannette Schaeffer), hearing impairment (Martina Penke & Monika Rothweiler), neurological disorders, or cognitive handicaps (Alexandra Perovic & Kenneth Wexler). Identification can be done through language, phonological or cognitive measures, taking into account phonological performance (Christophe dos Santos & Sandrine Ferré), the role of working memory (Vincent Torrens & Esther Yagüe), sentences repetition (Alice Fleckstein, Philippe Prévost, Laurie Tuller, Eva Sizaret & Rasha Zebib), and language properties (Anny Castilla-Earls, Ana Teresa Perez-Leroux, Adelaida Restrepo, Daniel Gaile & Ziqiang Chen). The articles included in this special issue take into account new theoretical developments, and some take into account bilingual populations, which were not included in previous studies.

The article by Schaeffer deals with the differentiation between Dutch-speaking children with SLI and with High Functioning Autism (HFA). She tries to solve the question of whether SLI and HFA are different impairments or whether these are impairments of the same continuum. In this study, the author runs tests on grammar, pragmatics, and nonverbal cognition. The grammar tests include the mass-count distinction and subject-verb agreement; pragmatics is evaluated by the distinction of definite and definite articles and direct object scrambling; general cognition is tested on nonverbal reasoning ability, nonverbal working memory, and nonverbal inhibition. She shows that while SLI children and children with HFA have a similar performance on pragmatics, children with SLI show higher linguistic and cognitive impairments. In fact, Schaeffer finds that the performance on grammar tests is independent of pragmatics. In addition, she finds that although nonverbal reasoning performance does not correlate with grammatical performance, nonverbal Working Memory has correlates with grammar performance. According to Schaeffer, SLI children have different symptoms and etiology from children with High Functioning Autism.

The article by Perovic & Wexler deals with the differentiation between English-speaking children with SLI and with Williams Syndrome (WS). These authors find no significant difficulties for SLI children on the acquisition of reflexive binding, whereas children with WS show difficulties with binding. It has been found in the literature that children with WS have difficulties with the development of pragmatics, whereas they have a well-preserved short-term memory; on the other hand, SLI children have many difficulties on nonword repetition but well-preserved pragmatics. Therefore, the performance on binding of children with WS and children with SLI tells us about which are the real causes of difficulties in the acquisition of Principle B in binding theory; more precisely, they try to find out if children have knowledge of the constraint on the necessity of a local c-commanding binder for a reflexive and the constraint on the ungrammaticality of a local c-commanding coreferential DP for a pronoun. Perovic & Wexler find that children with SLI and children with WS have the knowledge of the c-command constraint on the antecedent of a reflexive. In contrast, children with WS perform much worse on the knowledge of Principle B, and children with SLI are not significantly worse on the knowledge of this principle. Therefore, the cause of the difficulties with Principle B is a pragmatic difficulty and not a memory difficulty.

The article by Penke & Rothweiler tries to find tools to identify children with SLI in German and tries to find differences in the symptoms between SLI, hearing impaired (HI), and typically developing children; in addition, symptoms shared between these populations are also studied to show underlying processes. They run a standardized nonword repetition task and an experiment testing subject-verb agreement. The agreement affixes of the second and third singluar markers -st and -t are expressed by high-pitched consonants; we expect to find a low performance in the second and third singluar markers, since HI children have difficulties in perceiving high-pitched consonants. However, we expect to find more difficulties for the -n-marked plural forms in children with SLI, since the suffix -n is unstressed. The authors describe differences and similarities in error patterns between these populations. The authors find that SLI and children with HI obtain lower results compared to typically developing children in a nonword repetition and verbal agreement; however, the processes affected are different between these populations: SLI children have processing limitations, whereas HI children have a limited language input. For the subject-verb agreement task, HI children show a different pattern from SLI children. The results lead the authors to conclude that verbal agreement tasks can differentiate the profiles for SLI and HI children.

Dos Santos & Ferré present a test of nonword repetition as a tool for SLI identification. They test phonological structures in monolingual and bilingual children with and without SLI. This article faces the issue that tests to detect SLI are standardized on a monolingual population, and therefore SLI in bilingual children could be either underdiagnosed or overdiagnosed. To control the influence of lexical knowledge, these authors applied a measure of wordlikeness. The goals of this study were to find out if complex nonwords are more frequently failed, if French phonological complexities are better mastered by French monolinguals compared to bilinguals, and to develop a screening tool for detecting children with SLI for several languages. These authors created items that were “language dependent” (LD) and “language independent” (LI), which should have a phonological structure possible in most languages. The results of a LITMUS-NWR-FRENCH test show a statistically significant difference between the performance of Bi-SLI and Bi-TD children, which suggests that the LITMUS-NWR-FRENCH is a good indicator of SLI in bilingual children. These authors have also found that performance decreases as the number of syllables increases in the repetition tasks for SLI children, which is explained by the role of a working memory deficit; also, when two consonant clusters are present within nonwords, performance decreases for SLI children. It looks like this test can differentiate between children with and without SLI, taking into consideration other variables such as bilingualism.

Castilla-Earls et al. study the subjunctive mood in complemental and adverbial clauses as a grammatical marker to differentiate bilingual children with and without SLI. They try to supply a language measure for SLI in a bilingual population. They compare asymmetrical bilinguals with strong Spanish proficiency but limited English language proficiency and children who were either balanced or near balanced in their English/Spanish proficiency. To have a language measure, they run an elicitation task with grammatical structures that include a subtest for the subjunctive. To analyze data, they apply a generalized linear model, and the results show that age, bilingualism, and language impairment play a role for the accurate production of the subjunctive. Another goal of the article is to show properties that define both groups of children: For both SLI and TD children, temporal errors are about half of all incorrect verbal responses; mood errors is the most frequent error form in SLI children compared to the mood errors found in TD children; TD children perform better than SLI children for temporal clauses in both bilingual groups. These authors conclude that measuring the development of the subjunctive can help us to identify SLI children in a Spanish-English bilingual population.

Fleckstein’s et al.’s article investigates the use of a sentence-repetition task on bilingual children as a clinical marker for SLI children. Tests that are useful in monolingual populations might not be good identifiers in bilingual children because language properties of bilinguals often resemble the language behavior of SLI children: They omit the auxiliary and produce root infinitives, have difficulties with verbal morphology, produce object clitics significantly less often, significantly produce the least complex structures in wh-questions, and produce significantly more subject relatives than object relatives. Bilingual Arabic–French-speaking children and English–French-speaking children were grouped as SLI or typically developing (TD) children; these authors compared the performance with two control groups of monolingual children with TD and monolingual children with SLI. Fleckstein et al. run the French LITMUS-SR-French task, which includes five target (monoclausal sentences in the present, monoclausal sentences in the past, object wh-questions, complement clauses, and relative clauses). The results show that children with SLI performed significantly worse than TD children in the bilingual and the monolingual conditions; the identical repetition scores of the SLI and TD children on the whole task were significantly different among bilinguals and monolinguals. Differences were also significant on each structure. The results suggest that the LITMUS-SR-French task differentiates between SLI and TD children in monolingual and bilingual populations.

The article by Torrens & Yagüe studies three measures of phonological working memory as tools to identify SLI children: word repetition, nonce word repetition, and digit memory. They propose that a deficit in the phonological loop could cause a delay in the acquisition of lexicon, morphosyntax, and discourse. In this research they try to find out whether the scores in these three measures correlate with language performance in SLI and normally developing children. They collected data from 24 children—12 SLI children and 12 normally developing children—and both groups were matched for age. All children were Spanish-speaking monolinguals. They run tests of word repetition, nonce word repetition, digit memory, and language tests on lexicon and morphosyntax. They find that SLI children scored lower than normally developing children in word repetition, nonce word repetition, and digit memory for all age groups. In the nonce word-repetition task, they noticed that the accuracy of pronunciation of SLI children is worse than normally developing children, especially for low-frequency syllables. When SLI children repeat nonce words, they produce more inversions, omissions, and assimilations than normally developing children. Scores of the tests show that these can differentiate SLI and normally developing children for all age groups. The difficulties in nonce word repetition increase as the number of syllables also increases, and low-frequency syllables are more difficult than high-frequency syllables. They also find a statistically significant correlation between phonological working memory tests and the language tests. The results of this research suggest that processing limitations may increase the language difficulties of SLI children.

We hope to contribute with an overview of some of the issues on the identification of SLI children by inclusion and exclusion. We cover languages like Dutch, English, French, German, and Spanish in monolingual and bilingual populations.

This publication is one of the outcomes of the Workshop in SLI (SLI-w) that took place at the Universidad Nacional de Educación a Distancia (UNED) in Madrid. We would like to thank the support of the Agency of Research of UNED and the anonymous reviewers of all the articles.