Multilingual Aspects of Signed Language Communication and Disorder
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Multilingual Aspects of Signed Language Communication and Disorder
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Overview
Product Details
| ISBN-13: | 9781783091294 |
|---|---|
| Publisher: | Multilingual Matters Ltd. |
| Publication date: | 02/10/2014 |
| Series: | Communication Disorders Across Languages , #11 |
| Edition description: | New Edition |
| Pages: | 280 |
| Product dimensions: | 6.15(w) x 9.20(h) x 0.60(d) |
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Multilingual Aspects of Signed Language Communication and Disorder
By David Quinto-Pozos
Multilingual Matters
Copyright © 2014 David Quinto-Pozos and the authors of individual chaptersAll rights reserved.
ISBN: 978-1-78309-129-4
CHAPTER 1
Considering Communication Disorders and Differences in the Signed Language Modality
David Quinto-Pozos
Introduction
Over five decades of inquiry into signed languages have allowed language and communication researchers to expand what is known about structural variation and human language, patterns of language learning, and the cognitive processing of language by children and adults. Surprisingly, comparatively little work during this same period has focused on signed language communication disorders even though there are likely thousands of signed language users (including school-aged children) throughout the world who possess some type of signed language deficit. Perhaps one reason for the lack of research on this topic lies in a major challenge faced by researchers. Specifically, there is much variation among deaf signers with respect to whether they have language input from models who are fluent in a signed language; this is true both for first exposure and for regular interaction with native or native-like language users. For many deaf children atypicality has been viewed as simply a developmental phase – something that is expected to 'go away' as they get older. Unfortunately, this view has resulted, at least in some cases, in late identification of linguistic and/or cognitive deficits that could have been addressed earlier. This chapter and this volume are intended to serve as a resource for researchers and clinicians on the topic of signed language communication disorders, and on the question of how disorders of visual language might be considered within the contexts of deaf, hard of hearing and hearing individuals who acquire and use a signed language.
Similarities and Differences Across Modalities
A major question within this area of inquiry is the following: how are signed language communication disorders similar to or different from spoken language communication disorders? Recent writings have also addressed this question (Woll, 2012; Woll & Morgan, 2012). Presumably, we should expect multiple parallels across disorders of signed and spoken languages because of similarities between signed and spoken language structures and between the ways in which both types of languages are acquired by children. However, we might also expect characteristics of each modality to influence the types of communication disorders that appear in signers and speakers; some possible areas of consideration include the linguistic signal, the articulators used for language, and the articulator space. See Table 1.1 for a summary of the comparisons. In this section, sign and speech are compared in order to provide the researcher, the student and the practitioner with a way to consider possibilities for communication disorders in signed languages.
Similarities
Signed languages are natural languages that are structurally similar to spoken languages
For decades, research has shown that signed languages are natural languages that can be described with reference to levels of structure that characterize spoken language such as phonology, morphology, syntax and semantics/pragmatics (see, for example, Brentari, 2012; Emmorey, 2002; Johnston & Schembri, 2007; Klima & Bellugi, 1979; Sandler & Lillo-Martin, 2006; Woll & Sutton-Spence, 1999). For example, lexical signs can be broken down into multiple phonological units with handshape, place of articulation, movement and palm orientation values specifying how a sign is to be articulated. Linguistic descriptions of signed minimal pairs and performance-based slips of the hand (i.e. errors where target phonological features of a sign are incorrectly produced) provide evidence for the sublexical structure of sign (Hohenberger et al., 2002; Klima & Bellugi, 1979). Many authors have suggested that the movement of a sign is a key feature of signed syllables, although there is less agreement about the internal structure of the signed syllable (see Emmorey, 2007; Jantunen & Takkinen, 2010; Wilbur & Allen, 1991; Wilbur & Petersen, 1997). Consistent with the sublexical structure of signs, phonological disorders (e.g. Broomfield & Dodd, 2001) may appear in certain signers, with characteristic errors in one or more phonological values within signs (also see Corina, 1998 for paraphasias in adult aphasics). One report of children's deficits with signed phonological structure appears in Quinto-Pozos et al. (2011), in which second-hand accounts of deaf children who struggle with movement, place of articulation and palm orientation of signs are described. For that study, the authors interviewed professionals at bilingual (ASL-English) schools for the Deaf about their experiences with native signing deaf children who appear to be struggling with the acquisition of American Sign Language (ASL).
Evidence of struggles with aspects of signed language phonology can be found in the language production of children who have been diagnosed with autism spectrum disorder (ASD). In the current volume, Shield and Meier describe incorrect palm orientation or movement values that are produced by deaf children with ASD. For example, rather than fingerspelling with the palm facing toward an interlocutor, they sometimes have their hand turned toward themselves. This type of error is apparently unattested in typically developing children over the age of 18 months of age. The authors argue that the palm orientation errors during sign production are evidence of impaired perspective-taking abilities for the ASD children. A learner of a signed language must attend to orientation of the palm (i.e. the direction in which the palm is facing) in order to correctly produce a sign, since signs look rather different to the addressee than they do to the signer. Since perspective taking is typically challenging for children with ASD (hearing or deaf), children who are acquiring a signed language may show effects within their linguistic development. The signing space and perspective taking are discussed in more detail in the next section. Shield and Meier also provide an extensive review of pertinent literature on ASD and provide other examples and suggestions of the types of language impairments that might be expected in deaf children who have been diagnosed with ASD. Their work represents some of the first writings on this topic (see also Denmark, 2011; Shield & Meier, 2012).
Neurological evidence for similarities across modalities
Research on brain structures that are crucial for language comprehension and production also suggests that we might expect some similar neurogenic disorders across modalities. There exists much evidence for adult disorders of signed language in the form of case studies of deaf stroke patients who were fluent in signed language before a cerebral insult (American Sign Language: Emmorey et al., 1995; Hickok et al., 1996; Loew et al., 1997; Poizner et al., 1987; British Sign Language: Marshall et al., 2004). These aphasia studies indicate that brain structures commonly used by spoken language are similar to those used by signed language (also see Tyrone, this volume, for additional discussion). As would be expected, signers with damage to left hemisphere networks (in particular the inferior frontal cortex and the temporal lobes) have difficulty with comprehension and/or production of sign, whereas signers who experience damage to the right hemisphere do not have the same language problems.
Neuroimaging studies have also provided evidence for the important role of the right hemisphere in signed language communication. Although some researchers have found no differences between signers and speakers with respect to lateralization of language across modalities (e.g. MacSweeney et al., 2002), others have suggested that there is a greater involvement of the right hemisphere for sign over speech (Neville et al., 1998; Newman et al., 2002). With respect to production, signed language classifiers have been shown to recruit the use of the right hemisphere. In particular, the placement and movement of classifier constructions have been shown to engage bilateral networks (Emmorey et al., 2005, 2013), and some studies even suggest that classifiers and lexical signs engage different hemispheres during production (Hickok et al., 2009). The use of right hemisphere networks for aspects of signed language production and comprehension supports the premise that the right hemisphere can play a key role in some aspects of language, although there are also many similarities across modalities with respect to the networks that are engaged.
The degradation of brain tissue and function that results in dementia (for example as an accompaniment to Parkinson's or Alzheimer's diseases) can also be the source of atypical or impaired signed language abilities. An early report describing patterns of signing in Parkinson's patients appears in Kegl and Poizner (1998); the authors also analyze the techniques that are used by interlocutors to compensate for the Parkinson's patient's lack of appropriate attention during signing and less-than-clear articulation (i.e. maximization of distinction in linguistic contrasts by the interlocutors). In a recent study, Falchook et al. (2012) described the case of a deaf individual with Alzheimer's disease and her challenges with the production and comprehension of finger-spelling and grammatically complex sentences. The signer was also reported to exhibit impaired episodic memory, signs of anomia, an ideomotor apraxia and characteristics of a visual-spatial dysfunction. Cases such as these have provided evidence that dementia affects signed language abilities in deaf signers, as would be expected.
Additional cases of dementia and its effect on signed language use are described in the chapter in the present volume from Spanjer, Fieret and Baker. These authors describe various types of atypical language production that are evident in data from four older deaf users of Sign Language of the Netherlands (NGT) who are suffering from symptoms of dementia. In particular, they identify language problems that tend also to plague hearing users of spoken language with dementia, such as word finding difficulties, grammatical errors and inappropriate (i.e. pragmatically odd) responses. Additionally, they carefully consider the bilingual status of those patients (NGT and Dutch) and why that aspect of language learning must be considered when addressing the linguistic abilities of deaf patients with dementia. The work of Spanjer and colleagues is particularly important because it considers the language and communication abilities of multiple signers and also considers the data from a bilingual perspective.
Similarities concerning childhood acquisition of language
Signed languages are acquired by native-signing deaf children following a timeline that largely parallels the acquisition of spoken language by hearing children (Baker & Woll, 2008; Bonvillian et al., 1983; Newport & Meier, 1985; Petitto, 1987). Because of similarities in acquisition across the two modalities, we might also expect children to exhibit developmental signed language disorders paralleling at least some of those that have been identified and studied for spoken language. Symptoms of those disorders might be language delay, language processing deficits and issues concerning language and memory (see Schwartz, 2009 for an overview of child spoken-language disorders). Additionally, we might expect to find cases of specific language impairment (SLI) in children acquiring a signed language (e.g. see Mason et al., 2010; Morgan et al., 2006; Quinto-Pozos et al., in preparation), since SLI is a disorder of language comprehension and/or production that manifests in otherwise typically developing children (Leonard, 1998).
A chapter in this volume on deaf children acquiring British Sign Language (BSL) provides evidence for SLI in deaf signing children. The collective work of Herman and colleagues is notable because it represents the first set of in-depth studies that have considered communication disorders in signed languages. In their chapter for this volume, Herman, Rowley, Marshall, Mason, Atkinson, Woll and Morgan describe the main components of their several-years study of atypically developing deaf children in the United Kingdom. They detail a survey methodology that they have used for the identification of atypically developing children and they describe the tests of BSL comprehension and production that they administered. An overall claim from multiple studies conducted by members of that team is that signed language disorders are to be expected in a fraction of the population matching the proportion of children expected to have SLI in the acquisition of English, or approximately 7% of deaf children (Herman et al., this volume; Mason et al., 2010). The sign disorders resemble delays in language acquisition rather than idiosyncratic examples of language production, not unlike hearing children's spoken language disorders. Without a doubt, the BSL researchers have been pioneers in this area of developmental research on communication disorder in sign.
Differences
One might also expect a subset of signed language disorders to differ from spoken language disorders because of key differences between sign and speech. The modalities differ with respect to the signal in which language is encoded (e.g. auditory versus visual) and with respect to the articulators and articulatory space used for producing and comprehending language. There are also linguistic features of signed languages that might result in unique characteristics of at least some signed language disorders. In particular, it could be argued that signed languages appear different from spoken language with respect to characteristics of vocabulary items and how those items may be structured in the mental lexicon. The consideration of vocabulary items and related grammatical processes (e.g. a verb sign and its manner of inflecting for person and number) requires a discussion of iconicity and gestural resources and how those features of communication might influence signed language structures.
Differences in the linguistic/communicative signals
Since signed languages are typically perceived by the eyes rather than the ears (except in the case of tactually produced and perceived signed language, which is used by many individuals who are deaf and blind; see Quinto-Pozos, 2002), it may be useful to highlight a few key differences between the auditory and visual signals. Light travels much faster than sound does, and the speed of light at small distances appears instantaneous to humans (see Brentari, 2002 for a discussion). Meier (2002) points out that for sign, the source of the signal (i.e. light) is external to the signer, whereas for speech the sound is generated within the speaker (also see Tyrone, 2007 for a discussion). Meier also suggests that the visual signal has the capacity to capture a greater amount of information than the auditory signal can relay within the speech stream. This phenomenon can be exemplified by appealing to the concept of bandwidth as it applies to auditory versus video recordings; a 60-second audio file requires much less memory for storage than a 60-second video file does. It has been suggested that bandwidth differences could support an advantage in vision for vertical processing (i.e. processing simultaneously occurring information), but not in horizontal processing (i.e. sequential information) across time (Brentari, 2002; Emmorey, 2007).
One question to consider is how characteristics of the signal might influence the ways in which language is processed. Presumably, the processing of sequential information is of particular importance for spoken language because sounds are strung together to form words, and multiple words are arranged in sequence to create a sentence. The importance of sequence has been captured within theories of perceptual processing and language impairment. For example, the Auditory Processing Deficit (APD) hypothesis has been suggested to account for language deficits of hearing children (see Tallal & Benasich, 2002 for a review). The APD hypothesis claims that the speed at which phonetic elements in the speech signal must be processed is too rapid for children who struggle with temporal processing; this causes a notable percentage of otherwise typically developing children to exhibit developmental language impairment. Tallal's approach reflects the premise that children with language disorder can be characterized by a general slowing of processing vis-à-vis typically developing children (Tallal & Benasich, 2002). Whether the temporal characteristics of the visual signal could result in processing difficulties that are specific to signed languages is unclear.
The processing of sequential information is requisite in sign, as in the processing of phonological sequences in signs (e.g. handshape or place of articulation changes) or syntax. However, the processing of simultaneous information is equally important for signed language because of the typical linguistic structures of visual-gestural language. In sign, the synchronous use of manual and non-manual articulators allows for the creation of multiple simultaneously produced morphemes with information appearing on the hands and face; sometimes movement of the torso and body are also significant. For example, a lexical verb in ASL such as DRIVE is produced with the hands, modification of the verb with quickly repeating path movements adds a simultaneously articulated aspectual morpheme, and an additional adverbial modifier is communicated by postures of the lips and mouth area that encode information about the manner (e.g. carefully, haphazardly, etc.) in which the driving was conducted. Thus, linguistic and emotive facial expressions – in addition to manual articulations – are part of the signal to be deciphered by a viewer of sign. There is clearly much occurring simultaneously in sign. Spoken languages also allow for multiple simultaneously produced morphemes (e.g. a lexical item produced with grammatical tone), although spoken languages generally prefer concatenative morphology, with strings of affixes being the typical realization of morphological processes (Fernald & Napoli, 2000; Aronoff et al., 2005).
(Continues...)
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Table of Contents
Contributors vii
Foreword xiii
Preface xv
1 Considering Communication Disorders and Differences in the Signed Language Modality David Quinto-Pozos 1
Part 1 Developmental Language Disorders in the Signed Modality
2 Profiling SLI in Deaf Children who are Sign Language Users Rosalind Herman Katherine Rowley Chloë Marshall Kathryn Mason Joanna Atkinson Bencie Woll Gary Morgan 45
3 A Case-study Approach to Investigating Developmental Signed Language Disorders David Quinto-Pozos Jenny L. Singleton Peter C. Hauser Susan C. Levine 70
4 The Acquisition of Sign Language by Deaf Children with Autism Spectrum Disorder Aaron Shield Richard P. Meier 90
5 Mapping Out Guidelines for the Development and Use of Sign Language Assessments: Some Critical Issues, Comments and Suggestions Wolfgang Mann Tobias Haug 123
Part 2 Fluency Disorders, Neurogenics and Acquired Communication Disorders
6 A Review of Stuttering in Signed Languages Geoffrey Whitehead 143
7 Sign Dysarthria: A Speech Disorder in Signed Language Martha E. Tyrone 162
8 The Influence of Dementia on Language in a Signing Population Patricia Spanjer Mariëlle Fieret Anne Baker 186
Part 3 Hearing Children from Signing Households
9 KODAs: A Special Form of Bilingualism Anne E. Baker Beppie van den Bogaerde 211
10 Language Development in ASL-English Bimodal Bilinguals Deborah Chen Pichler James Lee Diane Lillo-Martin 235
Index 261