ANN SUTTON Université de Montréal. JILL P. MORFORD University of New Mexico. TANYA M. GALLAGHER University of Illinois at Urbana Champaign - PDF

Applied Psycholinguistics 25 (2004), Printed in the United States of America DOI: S X Production and comprehension of graphic symbol utterances expressing complex propositions

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Applied Psycholinguistics 25 (2004), Printed in the United States of America DOI: S X Production and comprehension of graphic symbol utterances expressing complex propositions by adults who use augmentative and alternative communication systems ANN SUTTON Université de Montréal JILL P. MORFORD University of New Mexico TANYA M. GALLAGHER University of Illinois at Urbana Champaign ADDRESS FOR CORRESPONDENCE Ann Sutton, PhD, École d orthophonie et d audiologie, Université de Montréal, CP 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada. ABSTRACT We explored production and comprehension of complex sentences constructed using a limited vocabulary on a graphic symbol display with voice output by 25 adults who use augmentative and alternative communication. When asked to construct subject (SS) and object (OS) relative clause sentences, only a minority of participants encoded SS and OS relative clause sentences using different word orders. When asked to interpret graphic symbol utterances, most participants chose an SS interpretation. Thus, the word order used most frequently in production appeared to have a single preferred interpretation. The relationship between the word orders produced in graphic symbol utterances and the way the same word orders are interpreted is not necessarily straightforward. Augmentative and alternative communication (AAC) systems have been developed to address the complex communication needs of children and adults with severe expressive communication impairments (i.e., that preclude the use of speech for daily communication). In many AAC systems, in particular those designed for children who are not yet able to read, messages are composed by selecting sequences of graphic symbols, representing words and concepts, arranged on visual displays and devices incorporating synthesized or digitized speech (Beukelman & Mirenda, 1998). Use of graphic symbol AAC systems rather than speech for expressive communication while language learning is underway presents unique challenges that may impact the nature of the linguistic skills children ultimately 2004 Cambridge University Press /04 $12.00 Applied Psycholinguistics 25:3 350 acquire (Blockberger & Sutton, 2003; Smith & Grove, 1999; Sutton, Soto, & Blockberger, 2002; von Tetzchner & Martinsen, 1996). As an example, use of expressive grammar by typically developing children is determined by their own inherent capabilities and their experience with mature language use models. In contrast, linguistic expression for children who use AAC systems is not solely under their own control: they construct their messages using vocabulary, tools, and strategies provided by intervenors (e.g., therapists, teachers, parents). Further, they use an output modality (visual graphic) that differs from the input modality (verbal auditory; Smith & Grove, 1999) and for which they have few models of competent use (von Tetzchner, 2000). Characteristics of graphic symbol AAC systems may place major constraints on production of language structure (see Sutton, Soto, & Blockberger, 2002, for a review). Restrictions that might be imposed on expressive communication for children in need of AAC are of particular concern when one considers the importance usually accorded to production in the process of language acquisition. Scholars attribute a variety of facilitative functions to production, including consolidation of new knowledge, analysis of units, practice, hypothesis testing, and social interaction (e.g., Boysson Bardies, 1999; Bruner, 1975; Chapman, 1992; Nuyts, 1992; Peters & Menn, 1993; Snow, 1999; Tomasello & Brooks, 1999), and some hold the strong view that production directly impacts linguistic representation or the process of acquisition itself (e.g., Liberman & Mattingly, 1985, 1989; Locke & Pearson, 1990; Studdert Kennedy, 1991). Others attribute a less prominent role to production and hold that opportunities for comprehension through language exposure are more important (e.g., Chomsky, 1986; Crain & Thornton, 1998). Thus, the atypical acquisition situation of children in need of AAC presents a unique context in which fundamental questions can be addressed by examining variables believed to influence language development but not typically under experimental control. In order to pursue explorations of language acquisition by children needing AAC, however, a deeper understanding of AAC message construction characteristics is needed. It is widely acknowledged that differences exist across AAC and spoken language forms and global characteristics of interaction (Beukelman & Mirenda, 1998; Gerber & Kraat, 1992; Kraat, 1985; Light, Collier, & Parnes, 1985; Nelson, 1992; Udwin & Yule, 1991). However, few systematic investigations of the structures of AAC messages have been conducted to date. Utterances produced using AAC systems, in particular systems based on graphic symbols, are often described as reduced or different when compared to spoken sentences. Reductions and variations in constituent orders produced using AAC systems have been noted among children (e.g., Bruno, 1989; Kraat, 1991; Smith, 1996; Udwin & Yule, 1990), adolescents (Kelford Smith et al., 1989; Sutton, 1989), and adults (Nakamura, Newell, Alm, & Waller, 1998; Soto & Toro Zambrana, 1995; Sutton, 1989; Sutton, Gallagher, Morford, & Shahnaz, 2000), although participants with different communication profiles and using a variety of AAC systems were included in these studies. AAC utterances may appear reduced or different when compared to spoken sentence structures as a consequence of the design of AAC displays (i.e., which graphic symbols are included and how they are arranged on display surfaces). Grammatical markers and function words (e.g., articles, determiners, Applied Psycholinguistics 25:3 351 plurals, past tense, relative pronouns) may be eliminated from displays, especially those based on graphic pictures/symbols, in order to include as many content words (nouns, verbs, adjectives, adverbs) as possible within the limited space available. Space concerns are becoming less of an issue, given that technological advances permit, in principle, storage of large vocabularies and somewhat easier access to grammatical markers, but content words still tend to be favored by the choice and organization of vocabulary on a particular display surface. Patterns of interaction between persons using AAC and their speaking partners (e.g., Kraat, 1985) may also lead to differences between spoken utterances and those constructed using AAC displays. Interlocutors may attempt to facilitate interaction by finishing sentences started on the AAC display and by providing interpretations of symbol sequences that appear to be complete (i.e., early interpretation, as in Sutton, Gallagher, Morford, & Shahnaz, 2002). These practices serve to accelerate communication and may enhance the rate of information exchange, but they do not encourage production of complete syntactic structures, and in particular, multiclause structures. It may be difficult, therefore, for listeners or observers to recognize the structure of AAC utterances, especially those containing complex structures. Theoretical perspectives currently under exploration in the literature attribute the differences in structures used in AAC utterances spoken language sentence structures to the use of compensation strategies or to characteristics of the visual graphic communication modality. It is proposed that compensation strategies may be used in order to convey the desired message, despite cognitive, physical, and linguistic constraints imposed by the need for an AAC system (von Balkom, 1998; von Balkom & Welle Donker Gimbrère, 1996). Alternatively, modality-specific (i.e., visual graphic vs. auditory oral) characteristics may determine the shape of possible messages (Smith, 1996; Soto, 1997). These perspectives are not necessarily mutually exclusive, and it is likely that both compensation and modality (as well as other factors) influence message construction using AAC systems. Although not specifically designed to test these theoretical contrasts, studies to date involving participants with no disabilities tend to support the modalityspecific hypothesis (e.g., Nakamura et al., 1998; Smith, 1996; Sutton & Morford, 1998; Sutton et al., 2000). The research strategy typically used in these studies has been to ask participants with no disabilities to use a graphic symbol display to construct utterances of different types in situations where factors requiring compensation strategies are controlled. For example, the possibility that vocabulary limitations might influence production was controlled by including all vocabulary needed to construct target sentences on the symbol displays used. Ease of physical access to vocabulary was ensuring that the size of the displays was well within the range of easy access by individuals with no motor impairment (i.e., no larger than a standard page or laptop computer screen). Facility with the content and operation of the AAC system used for the experimental tasks was guaranteed by providing familiarization and training. These studies found that, when compared to spoken models, constituents were omitted and/or reordered in sentences constructed using graphic symbols by both speaking children (Smith, 1996: Sutton & Morford, 1998) and adults (Nakamura et al., 1998; Sutton et al., 2000). Further, these modifications seemed systematic rather than random or idiosyncratic, Applied Psycholinguistics 25:3 352 suggesting that the modality of expression (visual graphic symbols) influenced the utterance structures used. Analyses of utterances produced by individuals who use AAC for daily communication suggest that the modality of expression influences utterance structures in ways similar to those noted in studies of participants with no disabilities, but a variety of additional characteristics were also observed (see Soto, 1997, 1999, for reviews). Some of the commonalities mentioned could be described as compensations rather than strictly modality-specific characteristics, such as the use of circumlocutions used in order to explain a word meaning that was unavailable on the individual s AAC system. Studies reviewed by Soto (1997, 1999) were primarily analyses of utterances produced by individuals using AAC in conversation but studies including participants with no disabilities involved experimental sentence construction tasks. At present, studies are lacking that provide comparable data regarding utterances constructed using a visual graphic AAC system by participants with no disabilities and participants who use an AAC system for daily communication. The aim of the present study was to examine utterances produced by participants who use AAC for daily communication on a controlled experimental task that had previously been used with participants with no disabilities (Sutton et al., 2000). Sutton et al. (2000) asked adult speakers of English to use a graphic symbol display with speech output to construct two types of complex sentences that were presented verbally with an accompanying photograph. The complex sentences containing two predicates were subject relative clause sentences (SS, e.g., The girl who pushes the clown wears a hat. ) and object relative clause sentences (OS, e.g., The girl pushes the clown who wears a hat. ). The graphic symbol display contained a small vocabulary and no grammatical markers (e.g., third person -s and relative pronoun who ), in order to explore sentence construction when word order was the only available means of indicating relationships among the constituents, as would be the case when grammatical markers are absent from an AAC display. Thus, the two sentence types (SS and OS) would be ambiguous based on the content words alone (e.g., GIRL PUSH CLOWN WEAR HAT). If participants attempted to use two different word orders to convey the two types of utterance structures, they would be obliged to modify the sequence of the spoken words they heard. The large majority of the participants used two different word orders for SS and OS sentences, although a total of nine different word orders were used across the two sentence types. The most frequent response pattern observed was to maintain the proximity of the attribute (e.g., WEAR HAT, or HAT alone) and its noun even though this tendency sometimes resulted in constituent orders that differed from the spoken English word order (e.g., GIRL WEAR HAT PUSH CLOWN or GIRL HAT PUSH CLOWN for the SS sentence The girl who pushes the clown wears a hat, contrasted with GIRL PUSH CLOWN WEAR HAT or GIRL PUSH CLOWN HAT for the OS sentence The girl pushes the clown who wears a hat ). Most individual participants used a single response pattern across the majority ( 85%) of trials. Thus, the participants were consistent in the ways they constructed two distinct types of complex sentences on a graphic symbol display. The present study explored production of the same complex structure containing two predicates, subject (SS) and object (OS) relative clauses, using a small Applied Psycholinguistics 25:3 353 vocabulary on a graphic symbol display with speech output, by adults who use AAC systems for their daily communication. A sentence interpretation task using the same structures was also administered. Three research questions were addressed. First, do adults who use AAC produce different word order patterns when using a graphic symbol display to construct utterances corresponding to distinguish SS and OS structures? Second, are similar word order patterns used within this participant group? Third, how do the participants interpret potentially ambiguous graphic symbol utterances corresponding to SS or OS sentences? METHOD Participants The participants were 25 adults whose native language was English and who used an AAC system for daily communication. All participants had a diagnosis of cerebral palsy and severe motor speech impairment and reported hearing and vision (or corrected vision) to be within normal limits. Additional cognitive and linguistic criteria for participation were kept to a minimum, given that accurate assessment of these skills is difficult for individuals with severe motor impairment. Criteria were applied only to assure that participants possessed the minimum linguistic skills necessary to perform the experimental tasks. Participants who reported completion of a regular high school curriculum were assumed to possess an adequate level of skill without further testing (see Table 1). All other participants demonstrated comprehension of spoken English syntax at least equivalent to 6- to 7-year-old level (i.e., exceeding the age at which typically developing children comprehend and produce relative clauses; e.g., Crain, 1987; Crain, McKee, & Emiliani, 1990). Because language tests for older individuals that cover sentence-level syntactic comprehension are rare, the Grammatic Understanding subtest of the Test of Language Development Primary (TOLD-P; Newcomer & Hammill, 1982) was chosen to assess comprehension level. The picture-choice response format could be adapted relatively easily for individuals with physical limitations, and the test covered the age level at which children typically acquire relative clauses. In-depth assessment of language and communication measures (e.g., typical patterns of sentence use, types of clauses produced spontaneously, conversational skills) was not carried out with the participants. It is difficult to evaluate these skills in individuals who use AAC in ways comparable to those used with speaking individuals (Hunt Berg, 2001; Müller & Soto, 2001; Sutton & Gallagher, 1995), and the study was not designed to explore hypotheses of the relationships of these skills to the specific syntactic questions addressed. The participant description measures were selected with regard to the research questions rather than to provide a detailed or exhaustive discussion of each individual participant s language and communication skills. Participants used a variety of AAC systems for their daily communication, including systems based on graphic symbols, the alphabet, or a combination of these, and including systems accessed by direct selection, scanning, or eyegaze encoding (see Table 1). Applied Psycholinguistics 25:3 354 Table 1. Participant (PAR) gender (M/F) and age (years); symbol set, type of output, and accessing method used in personal AAC system; and education Gender/ Symbol Voice Participant Age Set Output? Access Education PAR1 M/33 WRITE system, No Number code Adapted program Blissymbols PAR2 F/34 WRITE system, No Number code Adapted program Blissymbols PAR3 M/35 Blissymbols No Direct selection Adapted program PAR4 F/29 Blissymbols, Yes Direct selection Adapted program printed words PAR5 F/38 Picsyms Yes Scanning Fifth grade PAR6 M/38 Blissymbols, No Direct selection Adapted program printed words PAR7 F/27 Printed words Yes Direct selection Adapted program PAR8 F/30 Printed words Yes Scanning Adapted program PAR9 F/63 Printed words, Yes Direct selection Adapted program sentences PAR10 M/38 Alphabet Yes Direct selection High school PAR11 F/46 Alphabet Yes Direct selection Eighth grade PAR12 F/39 Alphabet Yes Direct selection High school PAR13 M/34 Blissymbols Yes Direct selection High school PAR14 F/33 Alphabet Yes Direct selection High school PAR15 M/28 Minspeak Yes Direct selection High school PAR16 M/30 Minspeak Yes Direct selection High school PAR17 M/28 Minspeak Yes Direct selection High school PAR18 F/24 Minspeak Yes Direct selection High school PAR19 M/33 Minspeak Yes Scanning High school PAR20 M/48 Minspeak Yes Direct selection High school PAR21 M/23 Minspeak Yes Direct selection High school PAR22 M/35 Alphabet Yes Direct selection High school PAR23 F/44 Blissymbols Yes Direct selection Third grade PAR24 F/30 Blissymbols No Direct selection High school PAR25 M/36 Blissymbols No Direct selection Adapted program Materials Photographs. The photographs depicted reversible agent action patient events enacted by figurines in which one of the figurines had a particular attribute. There were 16 photographs constructed by combining four pairs of people (Per-1, Per-2: girl clown, clown girl, boy clown, clown boy) with one of two reversible actions (Act: push, pull) and one of two attributes (Attr: hat, scarf). Graphic symbol display. The displays used in the study contained nine symbols from the Picture Communication Symbols picture set (Johnson, 1981, 1985, 1992) and were mounted on a MacawIII TM programmed to speak each word as the corresponding symbol was selected. Eight of the symbols represented the elements Applied Psycholinguistics 25:3 355 depicted in the photographs (people, actions, attributes), and thus constituted the vocabulary used in the experimental tasks. A separate symbol for start over was included on the display so that participants could change symbol selections, if needed. A different random arrangement of the symbols on the display was used for each participant. The spoken symbol labels recorded onto the MacawIII were controlled for speaker characteristics, sound quality, prosody, and loudness. All occurrences of each word were identical. One male speaker made all recordings in a sound booth. Each word was recorded one at a time, followed by a pause, onto high quality audiotape and subsequently recorded onto the MacawIII in the same square as the corresponding graphic symbol. Loudness of recording (live voice onto audiotape and taped words onto the MacawIII) was controlled by passing the audio signal through a clinical audiometer (GSI-10) set at 55 db HL (normal conversational speech level). Participants selected symbols on the display using the methods that they employed for their personal AAC systems. The MacawIII device incorporated both direct selection and scanning as selection methods. For participants who used
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