Handbook of Child Language Disorders

2nd Edition

Richard G. Schwartz

• Publisher: Psychology Press
• Year: 2017
• Print ISBN: 9781848725966
• eBook ISBN: 9781315283517
• Topic: Psychology
• Subtopic: Cognitive Neuroscience & Neuropsychology
• Index: Psychology

The acquisition of language is one of the most remarkable human achievements. When language acquisition fails to occur as expected, the impact can be far-reaching, affecting all aspects of the child's life and the child's family. Thus, research into the nature, causes, and remediation of children's language disorders provides important insights into the nature of language acquisition and its underlying bases and leads to innovative clinical approaches to these disorders.

This second edition of the Handbook of Child Language Disorders brings together a distinguished group of clinical and academic researchers who present novel perspectives on researching the nature of language disorders in children. The handbook is divided into five sections: Typology; Bases; Language Contexts; Deficits, Assessment, and Intervention; and Research Methods. Topics addressed include autism, specific language impairment, dyslexia, hearing impairment, and genetic syndromes and their deficits, along with introductions to genetics, speech production and perception, neurobiology, linguistics, cognitive science, and research methods. With its global context, this handbook also includes studies concerning children acquiring more than one language and variations within and across languages.

Thoroughly revised, this edition offers state-of-the-art information in child language disorders together in a single volume for advanced undergraduate students and graduate students. It will also serve as a valuable resource for researchers and practitioners in speech-language pathology, audiology, special education, and neuropsychology, as well as for individuals interested in any aspect of language acquisition and its disorders.

Part I
Typology of Child Language Disorders

1
Specific Language Impairment

Richard G. Schwartz

Terminology: “How Shall a Thing Be Called?” (Brown, 1958)

Roger Brown considered how children come to attach a word to things and categories of things in the world. Attaching words or names to things and categories is basic to human language—the label Specific Language Impairment (SLI) is one example. Our field came to this terminology through a long history, but recently some researchers have raised questions about its use and have suggested alternatives. I will consider some of those issues before describing this clinical category of child language disorders.

Reports of language learning disabilities in the absence of other developmental disabilities first appeared in the 19th century and grew exponentially beginning in the second half of the 20th century (see a recent review in Reilly et al., 2015). These children have been varyingly described as having congenital aphasia, congenital word deafness, congenital auditory agnosia, and congenital developmental aphasia, among other terms. Many of these earlier labels were based on inferred etiology and, to some degree, reflect parts of the elephant as described by the proverbial blind men. More recent terminology has included language disorder, delayed language, developmental language disorder, specific language deficit, specific language impairment, and, most recently, primary language impairment. Consistent among these terms is the assumption that these children have a language disorder in the absence of autism, general developmental/cognitive delays, identified genetic syndromes, hearing impairments, and seizures or other neurological conditions. These disorders are only specific in that exclusionary or idiopathic sense.

Two recent papers (Bishop, 2015; Reilly et al., 2015) have approached this issue of terminology in different ways. Capturing all of the carefully considered perspectives of these two keynote papers and all of the commentaries is beyond the scope of the discussion here, but I will briefly summarize some of the key points. Bishop considered the many advantages and disadvantages of labels and found that the former far outweigh the latter. Among the benefits of clinical labels can be in defining research populations, identifying children clinically, identifying strengths as well as weaknesses, and providing needed services including assessment, accommodations, and intervention. She noted that the wide variety of Language Learning Impairment (LLI) terms have divided the field and that although SLI has not been adopted outside of the research community, it is the most widely used term in the research literature.

Reilly et al. critically evaluated exclusionary and inclusionary criteria, revealing the weaknesses in the definition along with the quantitative criteria. All are certainly good points regarding the potential heterogeneity of deficits, language and non-language, and use this heterogeneity to argue for terminological change. I share the perspective offered by Leonard (2015), Rice (2015), and other commenters, that none of the other terms offered solve all the problems of SLI. There is good reason to suspect that, at some point in the future, SLI will no longer be viewed as idiopathic; we will identify neurobiological and genetic bases for SLI, along with their specific and universal cognitive-linguistic manifestations. An alternate term at this point would further divide the research literature as it already has been by terms like Language Impairment (LI—also the same as the abbreviation for Long Island) and Primary Language Impairment (PLI—also the abbreviation for Pragmatic Language Impairment). It is not clear what LLI would add. As several of the commenters noted, one of the most critical issues is the lack of use of SLI outside of research environments and the general lack of public awareness. Few efforts, other than the Raise Awareness of Language Learning Impairments campaign (RALLIcampaign, 2012) in the United Kingdom, have been made by researchers or by state, local, and national organizations to raise public awareness of not only the term but the impairment. It is this situation that must change, not the terminology. None of the other terms suggested seem to be any more palatable than SLI, and there is the now-established history.

Studies of specific language impairment (SLI) have become ubiquitous over the last four decades (Bishop, 1997; Leonard, 2014). A Google Scholar search (July 12, 2016) yielded 1,520,000 results for SLI, far more than for any other term (Bishop, 2015). This large body of research has significantly enhanced our general understanding of these impairments, while leaving us still uncertain about important aspects of their exact nature. We still do not know their cause(s), their range of manifestation, the course of their development, or the most effective remediation approaches. Our knowledge base has increased exponentially, allowing investigators to propose better-informed models of SLI, links to other childhood language disorders, and approaches to assessment and intervention.

SLI affects approximately 7% of the population, with boys affected slightly more often than girls (Tomblin et al., 1997). SLI may occur at the same rate in other populations of children with language disorders. If this is true, subgroups of children with autism, children with genetic syndromes, and children with hearing impairments may have SLI co-morbidly to their primary impairment. There is mounting evidence that SLI is genetically transmitted, and thus we expect to see familial patterns (see Chapter 10 by Tomblin). Siblings of children who have already been diagnosed with SLI are approximately four times as likely to have SLI as are children without a family history.

The definition continues to be primarily one of exclusion. SLI is an impairment of language comprehension, language production, or both in the absence of hearing impairment, the absence of a general developmental delay (i.e., a normal performance IQ), the absence of any neurological impairment (e.g., perinatal bleeds, seizure disorders), and no diagnosis of autism. It is only in this singular sense that this language impairment is specific. Despite these definitional exclusions, there is evidence that children may have co-occurring deficits. The SLI criterion for deficits in production and comprehension varies widely across research studies and schools. Cutoffs have included 1.00, 1.25, 1.3, or 1.5 standard deviations below the mean on one or more measures of language production and comprehension or performance in the lowest 10th percentile on such measures. There is no universal agreement on the quantitative criteria that identify children who are at risk for communication failures, academic failure, or social disvalue due to limitations in one or more components of language production or comprehension. A recent article argued that the cutoff should be 1.25 SDs below the mean, but of course this is arbitrary, and this area requires further research.

Children with SLI may have various limitations in general auditory and speech perception; limitations in central cognitive domains such as memory, attention, and executive functions; deficits in other cognitive functions such as problem solving, mental rotation, and mathematics; and deviations in neurological structure and function. They also have a relatively high incidence of dyslexia and other, more global, reading and writing disabilities, along with attention deficit disorders. The nature of these limitations and their relation to SLI remain controversial.

In this chapter, I provide a review of theoretical proposals concerning the bases of SLI, an overview of the language and related cognitive deficits common to SLI, and the relation of SLI to other language disorders in children. The threads that run through the chapter are the identification and subcategorization of SLI, the biology of SLI, the role that underlying cognitive deficits may play in the origins and maintenance of language deficits, and the relationships between SLI and other disorders.

Theories of SLI

Theories of SLI can be divided into two general groups: (1) those that explain SLI as a result of deficits in linguistic knowledge, typically attributed to delayed maturation or a deficient representation of language, and (2) those that explain SLI in terms of domain-general (with respect to language) or domain-specific deficits in cognitive or cognitive-linguistic processes. A number of proposals have emerged over the last several decades. The greatest limitation of many of these theories is that they are not sufficiently comprehensive to account for all of the deficits associated with SLI. Other proposals are, as yet, too vague. Finally, others still lack convincing evidence or have been demonstrated to be untrue. Accurate or not, these proposals are important for the research direction they provide and for their potential implications for assessment and intervention.

Linguistic Knowledge and Computational Explanations

Among the earliest proposals of linguistic knowledge deficits in children with SLI is the extended optional infinitive (EOI) account (Rice & Wexler, 1996a, 1996b; Rice, Wexler, & Cleave, 1995). This proposal maintains that children with SLI extend a period that occurs in typically developing children during which tense is optionally marked on verbs that occur in main clauses. The result is that finite verbs are produced without markers such as tense and number. The extended unique checking constraint (EUCC) account is an elaboration of the EOI account (Wexler, 1998, 2003). In the required linguistic operation of checking, a feature in a phrase must check all of the relevant functional categories in order for an element to be produced. According to this proposal, children with SLI experience an extended period in which they are limited to checking a single functional category. For example, for the third-person singular and for auxiliary and copula forms, both tense (TNS) and agreement (AGRS) must be checked, but a child with SLI can check only one of these functional categories, and thus production is blocked (see Chapter 13 by Leonard for a detailed discussion of this proposal). Although this proposal better accounts for morphosyntactic deficits in SLI across languages than the original EOI proposal does, other, processing-based explanations (described in following section) have also been offered for these deficits (e.g., see (Chapter 11 by Joanisse and Chapter 13 by Leonard)).

The Representational Deficit for Dependent Relations (RDDR) proposal (van der Lely, 1998; van der Lely & Stollwerck, 1997) suggests that children with SLI have a limitation in building long-distance dependencies that include any kind of syntactic movement affecting passives, wh-questions, object relative clauses, and pronoun or reflexive antecedent relations (referred to as anaphoric dependencies), as they are governed by binding principles. Movement is characterized as optional in children with SLI, which leads to deficient production of sentences with these structures as well as their interpretation. Simply put, the various versions of RDDR propose that children with SLI lack the linguistic structural knowledge necessary to establish anaphoric relations between pronouns and their antecedents, or long-distance relations between nouns or pronouns, or as gaps in relative clauses and in wh-questions.

Van der Lely (2005) revised this proposal and renamed it the computational grammatical complexity (CGC) hypothesis. According to this view, children with SLI are impaired in the linguistic representation or computations that underlie hierarchical, structurally complex forms in one or more components of language (i.e., syntax, morphology, phonology). For syntax, the proposal implicates the optionality of an obligatory linguistic operation called Move that increases complexity with each application. Complexity is the result of one or more applications of this operation, with each adding to the complexity of the sentence. Although the same level of detail is not provided for morphology and phonology, this makes the proposal more general, and thus it is more capable of explaining deficits in language domains other than syntax. The notion of optionality and the distinction between a representation versus linguistic operation deficits have yet to be specified.

A related proposal provides additional focus to this notion that children with SLI have a deficient grammar affecting certain complex sentences with long-distance grammatical relations (e.g., Friedmann & Novogrodsky, 2004, 2007; Novogrodsky & Friedmann, 2006; see also Chapter 6 by Schwartz, Botwinik-Rotem, & Friedmann and Chapter 17 by Fletcher & Frizelle). Although children with SLI appear to have the same general structural linguistic knowledge as their typically developing peers, their grammar seems to be deficient in the syntactic process of phrasal movement affecting reversible passives (Adams, 1990; Bishop, 1997; Leonard, Wong, Deevy, Stokes, & Fletcher, 2006; van der Lely & Harris, 1990; van der Lely & Stollwerck, 1996), relative clauses (Adams, 1990; Friedmann & Novogrodsky, 2004, 2007; Novogrodsky & Friedmann, 2006), and wh-questions (Deevy & Leonard, 2004; Ebbels & van der Lely, 2001; van der Lely & Battell, 2003). Notably, these same deficits have been reported in children with hearing impairment (see Chapter 6 by Schwartz, Botwinik-Rotem, & Friedmann and Chapter 4 by Waldman DeLuca & Cleary). According to this proposal, the challenge presented by these sentences does not lie in establishing long-distance dependencies but, rather, in the underlying phrasal movement and, even more specifically, in the assignment of thematic roles (e.g., agent, patient) to noun phrases that appear in noncanonical or atypical locations bec...

Table of contents

• Cover
• Title
• Copyright
• Dedication
• CONTENTS
• About the Editor
• Contributors
• Preface
• PART I Typology of Child Language Disorders
• PART II Bases of Child Language Disorders
• PART III Language Contexts of Child Language Disorders
• PART IV Deficits, Assessment, and Intervention in Child Language Disorders
• PART V Research Methods in Child Language Disorders
• Author Index
• Subject Index