department of Psychology, The Catholic University of America, Washington, DC, USA; 2Center for Applied Science and Engineering and Department of Linguistics, University of Delaware, Newark, Delaware, USA;3Children's Hearing and Speech Center, Neurobehavioral Sciences Department, Children's National Medical Center, Washington, DC, USA and 4Department of Education, The Catholic University of America, Washington, DC, USA
Among the most disabling impairments in patients with neural injuries are those affecting communication. Fortunately, advances in the technology of communication devices and communication training have greatly expanded the proportion of affected individuals who can reacquire the ability to communicate. Even when residual motor control is very limited, or when there are sensory impairments or parasite movements, technology exists to translate something that the would-be communicator can comfortably do into a means of operating a communication device (e.g., Gragnani, 1990; Gryfe, 1996; Kubota et al., 2000; Perring et al., 2003). Techniques also exist to help most persons with cognitive, language or behavioral challenges to enhance their level of participation and control (Trepagnier, 1996; Gorman et al., 2003). Nor is cost a major barrier, since devices and techniques to support communication are generally affordable, and third-party reimbursement has become increasingly available (Smith, 1998; Higdon, 2002).
Communication devices can make an important difference in the quality of life of people affected by disorders that result in impaired speech or writing (Tolley et al., 1995; Diener and Bischof-Rosarioz, 2004). Youngsters with severe movement disorder from cerebral palsy can pursue educational and career goals (McNaughton and Bryen, 2002). Patients with amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) can continue to communicate with their family, friends and colleagues when they can no longer speak (Doyle and Phillips, 2001). Patients in critical care need not be deprived of a means of interaction with their family members and care providers (Happ, 2001). People with significant core language impairments coupled with severe developmental disabilities can interact socially, communicate preferences, express feelings and conduct their own lives with the help of carefully selected augmentative techniques (Trepagnier, 1996; Happ, 2001; Hadjistavropoulos et al., 2001). There are also devices to facilitate computer access for individuals who have impaired ability to write or keyboard, for example persons with high-level spinal cord injury that reduces their upper limb control (Hurlburt and Ottenbacher, 1992). Finally, very young children for whom development of speech and/or language are at risk can gain a foothold in the communicative world, become active rather than passive agents, and begin to progress in social and communicative skills (Cress and Marvin, 2003).
It is not only possible, but vital, for people across the lifespan to gain the capacity to interact effectively with the people around them. Neither cognitive disabilities, nor absence of literacy skills, nor very young or old age, nor the temporary nature of the impairment, nor being on school vacation, is sufficient justification for any individual to be deprived of a means of communication. Unawareness of the fact that there are means to support communication by people with severe impairments is also not an acceptable justification. The more that healthcare providers, educators, consumers, family members and the general public know about supports for people with severe communication impairments, the more apt they will be to identify the need when it is present, and recognize that it can be addressed.
The people who will communicate with the device-using individual, and everyone who exerts influence on the communication context, are important to the success of the aided communication. This includes the individual's family, friends and colleagues, as well as educators and human services and healthcare providers (Granlund et al., 2001). In order to select the most useful techniques, the individual's needs and abilities, the characteristics of the living and working context, and the symptomatology and prognosis of the disabling condition all need to be taken into account. The physician's information regarding expected disease course will affect the selection of control modalities. The family's awareness of the individual's activities and communication partners will be important in deciding on the particular features the techniques will need to incorporate. Once the devices and techniques are acquired, conversation partners will need to modify their interactive style in order to foster participation by device-users (Russel, 1984).
The growing body of knowledge and clinical experience related to supporting communication by means of assistive devices and techniques is known as "augmentative and alternative communication", or, for (relative) brevity, "augmentative communication" or "AAC" (Beukelman and Mirenda, 1998). The people served are often referred to as "augmentative communicators", and will be referred to here, for convenience, as "communicators". The challenge of evaluating the potential communicator's needs and putting together an optimal means of addressing them is complex. Accordingly it is very important to involve someone with depth and breadth of experience and up-to-date knowledge in the AAC domain. While AAC specialists may come from occupational therapy, rehabilitation engineering, or other professions, it is necessary to obtain an evaluation and recommendation from a speech-language pathologist (an SLP) in order to acquire funding for purchase of a device. Ideally, a speech pathologist who is experienced in AAC will be the one to provide the overall guidance of the process of assessment, recommendations and integration of the techniques into the communicator's daily life. The SLP may work with other health professionals, such as an occupational or physical therapist and/or a rehabilitation engineer, to resolve questions of seating and positioning for maximum stability and function (Goossens' et al., 1989; McEwen and Karlan, 1990), and to identify the best control options within the individual's repertoire. The SLP will also be concerned with communicators' cognitive and language status, their goals and the contexts in which they will be participating (Beukelman and Ball, 2002). It is of particular importance that whoever manages the evaluation process be independent. Just as one would not ask a salesperson at a General Motors dealership for advice on what make of car to purchase, it is wise to obtain evaluation and recommendation services from professionals who have no financial connection with a particular device manufacturer.
Unfortunately, there is no central registry of AAC specialists. The family member, educator or healthcare provider seeking these services needs to review the human and information resources available in order to meet the communicator's needs as effectively as possible. The community is often a good information source, including associations of individuals with the same disabling condition. Appendix 1 lists some additional resources.
Once recommendations have been made, the communicator may wish to "test-drive" a potential purchase. Manufacturers' representatives can be of great help at this point, as they may be able to arrange for a loaner device, and can provide the necessary technical support for getting started. Manufacturers can also help navigate funding issues, as they have acquired considerable experience in dealing with third-party payers. The best route to obtaining financial help with purchase of communication supports may depend on the individual's circumstances; for example, the school system may provide devices for school-aged children and adolescents, and the state vocational rehabilitation system may be a source of funding for people who wish to work (Smith, 1998).
Simply acquiring a communication device does not in itself equip the individual to be a competent communicator. Training is needed for communicators and for their frequent communication partners. The communicator and family members may need help with technical aspects of device operation, for example, how to maintain calibration when using a device operated by direction of gaze. Training of this type is usually provided by the manufacturer's representatives Parents and teachers may be offered guidance for using the device to support development of a child's language and communication, generally by an SLP or educational specialist (Pebly and Koppenhaver, 2001). It is, unfortunately, difficult to obtain funding to support training, and the gap is often filled by manufacturers' representatives. Of necessity, the cost of this service will already have been folded into the purchase price of the device.
There are many kinds of actions that can be sensed and converted into the equivalent of a switch closure or a computer keystroke. Similarly, there are many types of effects that a switch closure, keystroke or equivalent can produce. Control input, on the one hand, and output, on the other, can be wholly independent of each other. Control inputs can range from tongue contact with switches to a "sip-and-puff" switch; from an eye-blink, as illustrated in Fig. 14.1, to changes in direction of gaze sensed by an infrared eye tracking system; from hitting a large, robust switch by extending a limb or inclining the head, to almost imperceptibly contracting a muscle in the forearm or slightly raising an eyebrow (Soderholm et al., 2001). There are switches that require sustained force, so that accidental bumping would not close them; and there are switches that require no force at all, merely contact. Some individuals with aphasic impairments of written expression have been able to use their residual speech as a control mode, by means of mass-market speech recognition software. Even dysarthric speech can be a viable control option in some cases (Goodenough-Trepagnier et al., 1992; Bruce et al.,
2003; Havstam et al., 2003). Control parameter values may be adjustable to fit the communicator's abilities.
Output is seldom, any longer, robotic-sounding synthetic speech. That has been replaced in most devices either by digitally recordable and re-recordable spoken messages, or by sophisticated text-to-speech software and a variety of more natural-sounding artificial voices, so that the communicator can choose an age- and gender-appropriate one. Of course the output of a computerized device need not be limited to just speech and/or text. Communication may be directed not only to persons in the immediate environment, but also to persons who will receive the communication at a future date, or who are a few miles or a continent away, or it may go out to untold numbers of people who access a web site. People also communicate with electronic and computer-aided devices, in order to control electrical devices in their environment, listen to music, edit photos, shop, seek information, manage finances, play games or take courses, and they will undoubtedly use computers in the near future to carry out other activities that most of us have not yet imagined. The individual with communicative impairment needs access to these capabilities as least as much as, if not more than, people who do not have deficits in motor control, language or cognition.
It can be helpful to think of AAC techniques and devices in terms of three categories. There are techniques that do not require any props, and techniques that involve non-electronic ones. These are sometimes called "no-tech" and "low-tech", respectively. Finally, there are electronic devices, which have for the most part come to involve computers of one type or another, and are sometimes referred to as "hi-tech". It is a misperception that devices that incorporate technology inevitably entail complexity for the people who will use these devices. Difficulty of learning or use is in most cases an indication of poor design or, at the least, poor fit to the consumer's abilities (Norman, 1993; Goodenough-Trepagnier, 1994; Norman, 2002).
In no-tech scanning, the conversation partner not only speaks both parts of the conversation, but also plays the role that a device would fulfill, for example by reciting the alphabet until the communicator indicates which letter is intended, perhaps by a facial movement or eye movement. Signs (borrowed from American Sign Language, the native language of many deaf people in this country) are another no-tech method. They have been useful for some hearing, language-impaired communicators with mental retardation, autism, or both, and can be used in combination with speech (Konstantareas, 1987). There is some evidence that using gesture at the same time as speech is helpful to the speaker (Clibbens, 2001).
In the domain of "low-tech", there are language boards that offer letters, chunks of words, whole words and messages. These are represented by regular or phonetically adapted spelling, pictures and/or symbols of various types (Goodenough-Trepagnier and Prather, 1981; Goodenough-Trepagnier et al., 1982; Musselwhite and Ruscello, 1984). Low-tech and no-tech have in common that there is no explicit output entirely under the communicator's control. Instead, communication depends on the conversation partner. These methods can be highly effective in many circumstances, and are indeed preferred in some (Doyle and Phillips, 2001). The language board never runs out of batteries. While a device may get left behind, a no-tech method is always available, as long as a knowledgeable communication partner is present, and it can offer greater privacy and intimacy within a conversation dyad. With a skilled familiar conversation partner, these techniques provide more rapid spontaneous communication than current devices, because the familiar partner can use special knowledge of the communicator and the context to guess ahead. At the same time, only an electronic device offers independent communication. Whatever the technique, there are advantages and disadvantages to be considered in the context of individual communicators and their activities and communication partners, and it is often the case that more than one technique is needed.
14.3 Communicative needs of particular clinical populations
Just as devices can be categorized, device-users are often considered in terms of the disability that is at the root of their need for communication support. This is a useful starting point; at the same time, however, it is important to recognize the diversity within any clinical category. A device that proves helpful for one individual with autism, or for one adult with acquired neuromotor impairment, may be wholly unsuitable for others who happen to share the same diagnostic labels. With this caveat, the following portion of the chapter will point out considerations that are often of special concern for particular disability groups.
An adult who can no longer speak intelligibly, a young adult with brain injury that impairs speech and makes new learning difficult, and a young student with severe cerebral palsy who has acquired basic literacy skills are some of the people to whom this category applies. Since these are largely people who do not have serious problems understanding language, the problem that shows up here in particularly stark relief is the issue of impoverished communication rate, a drawback that is common across all AAC. While English speakers may converse at rates of 200 and even more words per minute, most users of augmentative devices require as much as 3 minutes and others may take longer still, to produce half a dozen words of real-time output. Despite many ingenious attempts to improve this situation, the problem remains a major stumbling block to the successful integration of augmentative communicators in conversation, education and employment.
Communicators whose impairment is primarily motor in nature need a communication device with which they can express whatever message they intend. This requires combining the sounds of speech, generally by means of the rather complex way of representing speech sounds that standard English spelling provides. Spelling of individual words does not preclude use of software techniques, sometimes implemented in mass-market computers, as illustrated in Fig. 14.2, intended to accelerate and support communication. One such technique is "prediction", by means of which the software anticipates intended words based on letters already typed. With expertise, prediction becomes equivalent to a practised shorthand, and the communicator does not need to exert as much effort. Another approach, of which there are numerous variants, is to compose phrases in advance and store them for quick retrieval. Entire jokes or speeches, one's phone number, a phrase that will capture the listener's attention while a novel message is slowly composed (a "floorholder") or a slogan in support of a favorite team may be stored whole on the device. Retrieval of such pre-constructed messages usually involves some variant of a shift-key strategy. For example, instead of just hitting the "h" key (to produce the letter "h"), the user might first hit a designated shift key (usually called a "level" key, or part of a code) and
then the "h," to call up a message that had been constructed in advance. However, if the communicator cannot accomplish the precise verbal task she or he wishes to carry out, the ability to interject "How about them Redsox" at the socially appropriate moment does not suffice (Bedrosian et al., 2003), and communicators whose device does not provide easy access to a spelling mode of some type, or who do not have the skills to utilize spelling, are at a disadvantage.
Usability is important in all cases. Communicators with preserved cognitive and language skills rightfully expect to be able to utilize their device right from the start. While it is to be expected that one would make gains in skill and speed with experience, no communicator should be required to spend a long period as a trainee, as a prerequisite to effective use of a communication device.
As is the case for any group, whether it is a question of augmentative devices, glasses or orthopedic shoes, individual preference and acceptance is key.
The potentially most useful device will not do much good if the individual does not wish to use it, and a given individual may, for a number of reasons, prefer to use speech, however difficult it is to understand, rather than resort to the more intelligible channel offered by augmentative technology.
In the first years of life, typically-developing children use their oral mechanisms to engage in sound play, begin to produce words at around the time of their first birthday, and progress to word combination by 18 months of age. Typically-developing children's intensive vocal exploration is not available to children with significant physical limitations, who are unable to orchestrate the complex movements of the articulators needed to create differentiated word forms and build a basic expressive vocabulary. Absence of intelligible speech often has the secondary effect of relegating children with significant speech and physical impairments (SSPI) to a passive role in social interaction (see Volume II, Chapter 39). As a result of the direct and second-order effects of their deficit, young children with SSPI may experience their prime language-development years in a suboptimal manner, and accrue impairments in development of grammar, phonological awareness and metalinguistic skills that will undermine their literacy development (Wagner and Torgesen, 1987). To these individuals' deficits in mobility and opportunities to engage with their environment are added, then, the additional limitations of reading and writing impairments (Berninger and Gans, 1986; Koppenhaver and Yoder, 1992).
While comparable studies of individuals with motor limitations have not been carried out, the consequences of delay and suboptimality of exposure to language and communication experienced by deaf infants, and their amenability to intervention, may be instructive here. Delayed access to language, as happens with deaf infants who are not taught sign, or whose early exposure to sign is sporadic, has been found to result in language impairments and failure to acquire "native-speaker" level skills (whether in signed or oral language) (Mayberry and Eichen, 1991). Long-term effects on the representation of language in the brain have been documented (Kral et al., 2001; Leybaert and D'Hondt, 2003), and there is evidence of negative effects on other aspects of cognitive development (Mayberry and Eichen, 1991; Woolfe et al., 2002). The unfortunate sequelae of SSPI will, it is hoped, be minimized in children now growing up, with the help of early intervention, the entitlements provided in the Individuals with Disabilities Education Act, the new emphasis given to literacy as a metric of schools' educational success and the implementation of novel instructional and assistive technologies, which offer new ways for children to participate and learn.
Current understanding of how language typically develops can usefully inform the facilitation of language development in children with SSPI (Gerber and Kraat, 1992). For example, children's first words tend to be about things and events in the "here and now," with nouns predominating until the vocabulary reaches about 100 words, when the proportion of actions increases (Benedict, 1979; Bates et al., 1994). Function words remain relatively infrequent until the child has passed the 400-word mark. Although there is great variability among children regarding rate of lexical acquisition, the emergence of grammar coincides with mastery of sufficient vocabulary to facilitate word combination. Children initially learn from experience and interaction how to map words to objects, actions and attributes in the environment (Pinker, 1984; Golinkoff et al., 1994). Once they have some knowledge of syntax, they can use the information derived from syntactic relationships to intuit the meaning of unfamiliar words (Gleitman, 1990; Mineo and Goldstein, 1990). Clearly, maximizing the SSPI child's opportunities for interaction and providing a means to address lexical and syntactic development are important considerations in the design of AAC interventions.
AAC can scaffold early language learning and provide the means to engage in language practice and experimentation that otherwise would be unattainable. Augmentative techniques need to be applied to acquisition of morphological and syntactic structures as well as metalinguistic awareness (Paul, 1997;
Sutton et al., 2002). Voice output may facilitate the development of phonological awareness (Blischak, 1994; Paul, 1997), an effect that might be amplified by incorporating rhyming games and other tasks designed for building phonological awareness. While parents and service providers may find it appealing to offer devices that yield complete sentences from single selections, devices that primarily offer these strategies do not provide children with expressive language experiences that parallel those of their typically-developing peers.
Severe motor impairment from cerebral palsy does not entail severe cognitive impairment. Indeed it can co-exist with superior intellectual abilities. Often training with assistive technology can enable the capacities for independent expression that will in turn make it possible to assess, and thus better serve, the child's potential. Devices that are hardened to survive everyday use, have the numerous characteristics that make them practical (including light weight, small size and long battery-life), and the flexibility and power of a computer, such as the one illustrated in Fig. 14.3, may be considered for a variety of populations, including children with impairments in motor control as well as individuals, discussed below, who also experience cognitive impairments.
Individuals with mental retardation and other developmental cognitive disabilities
Not so long ago individuals with developmental disabilities whose communicative intent was hard to discern were not offered augmentative techniques, and this population continues to be seriously under-served. In part this stems from the complexity of diagnosing and addressing communication disturbances that are secondary to cognitive deficits (Beukelman and Mirenda, 1998; Mollica, 1999). It is also the case that many existing devices and techniques are a poor fit to the needs of people with significant mental retardation. When device operation demands a disproportionate share of the user's cognitive resources, there may be little left to meet the demands of message formulation and partner engagement. There are nevertheless AAC techniques and devices available that can support expression of communicative intent, and that can help introduce to persons with severe cognitive involvement the concept of indicating their preferences and thereby gaining a desirable outcome.
It is unfortunately the case that knowledge and skill barriers still preclude many from accessing augmentative services and supports. A large number of speech language pathologists have had neither academic coursework nor practicum experience in supporting communication development and use by individuals with significant cognitive limitations. Many clinicians lack the confidence and/or expertise necessary to exploit the potential of AAC tools for maximum consumer benefit: they may not understand how to assess communication skills at a pre-intentional or emerging intentional level, or they may be unable or unwilling to explore the range of technology options available, to customize the device to meet consumer needs, and to train individuals and their circles of supports in how to operate the devices or techniques and how to utilize them in the context of real-world exchanges. Since many families are not aware that their loved ones could benefit from communication technologies, they do not become advocates for the inclusion of these services in program planning. Policy and practice barriers, too, often hinder access to communication technology by individuals with cognitive limitations (Mollica, 1998, 1999). The recent position statement of the National Joint Committee for the Communication Needs of Persons with Disabilities clarifies that reliance on a priori eligibility criteria, such as chronological age, diagnosis or the absence of cognitive or other skills purported to be prerequisites, violates recommended practice principles by precluding consideration of individual needs (National Joint Committee for the Communication Needs of Persons with Severe Disabilities, 2003). Historically, many third-party payers, such as Medicaid and school districts, have denied requests on behalf of individuals with mental retardation for communication devices, presuming that such individuals would derive only limited benefits. In practice, however, the growing body of research documenting the efficacy of AAC in enhancing both language development and use (Sevcik and Romski, 1997; Rowland and Schweigert, 2000) reinforces that such discriminatory practices are unjustified. In fact, the availability of dynamic language representations (increasingly in portable and wearable form), voice output and flexible language organization may facilitate language development and communication in ways not possible through other means such as sign language or static picture cards.
Aphasia is the blanket term used for the myriad speech and language disorders that can result from injury to the adult brain, typically from a cere-brovascular accident or stroke, in most cases on the left side of the brain (see Chapter 26 of Volume II). The location, extent and type of lesion, as well as time after stroke or injury, are the main factors determining the type and severity of the aphasia (Pedersen et al., 2004); and these factors, in conjunction with treatment, also affect its course (Pradat-Diehl et al., 2001; Kiran and Thompson, 2003). While gains can be achieved years after onset, in general aphasia that persists after 1 year is considered chronic. In addition to reports by neurology and rehabilitation medical specialists, it is helpful to have a thorough evaluation of expressive and receptive written and auditory language carried out by a speech language pathologist who specializes in aphasia, and who is cognizant of therapeutic and augmentative techniques that have been of help to individuals with aphasic disorders.
Many individuals who experience aphasia in the period immediately after their stroke recover fully or recover with minor residual deficits. Residual aphasia may be as mild as a difficulty in retrieving names or other precise words in as timely a fashion as one would like. At the other extreme is chronic severe "global" aphasia. Individuals with aphasia of this type can make little sense of what people say to them and their attempts to speak may yield only a couple or at best a few "frozen phrases". Written language, for reading or writing, is also globally impaired in these severe cases. In between the extremes there is a broad range that is not linear. Some individuals may have specific impairments in the context of an otherwise high level of preserved language ability. Others may have some preserved skills that are the more remarkable compared with the severity of their overall level of language impairment. Persons with relatively preserved speech but impaired writing may be able to use augmentative technology in the form of speech recognition, to accomplish writing tasks (Wade et al., 2001; Bruce et al., 2003). Similarly, someone with severely limited speech may be able to convey specific words by pointing to words on a list. Augmentative approaches must accordingly be tailored to their users' profile of preserved and impaired abilities. If the ability to recall the initial letters of words, or subcategories of words, such as names or common nouns, is preserved, it can be a helpful component of a communication system, and visual support may help some individuals with aphasia to engage in conversation and transmit information (Goodenough-Trepagnier, 1995; Linebarger et al., 2000; Linebarger Schwartz et al., 2001; Garrett and Huth, 2002). While computerized systems that enable users to select and string together pictures standing for concepts are useful for some individuals with aphasia both for communication and as therapy (Weinrich, 1995), persons with global language impairment may not be able to relate spatial order of pictures or words to grammatical function, and may be unable to assign verb and preposition meanings to graphical representations at all (Goodenough-Trepagnier, 1989; Shelton et al., 1996).
Unlike individuals with congenital disabilities, who have not had the benefit of typical socialization, many individuals with aphasia retain the ability to read social situations and extract information from non-language cues. Directional skills are also generally retained, such that someone may be an effective navigator without, however, being able to provide verbal directions. Preserved social and spatial abilities may be put to use for communication via gestures, mime and drawing, which are helpful for some individuals, and can improve with training (Sacchett et al., 1999). While it is possible that a communication device designed for an adult with acquired neu-romotor disability, or a device developed for young children with cerebral palsy, could be useful for someone with aphasia, that can in no way be assumed. It should also be remembered that unlike the primarily motor-impaired population, many people with aphasic communication difficulties are ambulatory and some may continue to drive a personal vehicle. Accordingly, the range of contexts in which they might benefit from communicative supports can be large, and the need for a repertoire of techniques in keeping with the demands of different situations should be considered (Cress and King, 1999). As with other populations who use augmentative techniques, conversation partners can take steps to improve communicators' participation, with the help of appropriate training (Rayner and Marshall, 2003). A speech-language therapist specializing in aphasia, and who is also familiar with AAC techniques, can be of great help in this regard.
Autism is a lifelong disability with complex genetic origins (Folstein and Rosen-Sheidley, 2001) whose signal feature is a profound disturbance of social relations (Wing, 1976; Volkmar, 1987). The beginning of modern understanding of autism dates back to the mid-20th century (Kanner, 1943; Rimland, 1964). Scientific study of this spectrum of disorders began to gather momentum as general agreement was reached on diagnostic criteria around 1994 (American Psychiatric Association, 1994). The pace of autism-related research has increased rapidly in recent years, and has yielded improved methods of detection and intervention that can make a major difference in the individual's potential to live a satisfying life (Eikeseth et al., 2002). There is, however, no cure. It is estimated that as many as half of people with autism do not develop speech that is adequate to meet their communication needs (Sigman and Capps, 1997), and language impairment, in addition to the evident pragmatics deficits (Wing and Atwood, 1987; Beukelman and Mirenda, 1998), is present to some degree in most individuals on the spectrum (Rapin and Dunn, 2003). About 70% have mental retardation (La Malfa et al., 2004). While there are movement and motor control anomalies associated with autism, these are minor in relation to the overall picture of profound deficits. Motor impairments do not limit the AAC options for most people with autism, and indeed the fact that these individuals are almost all ambulatory and that many children are especially active puts its own sorts of constraints on augmentative choices.
Despite their mobility, children with autism share with SSPI children a key secondary consequence of their disability: exclusion from communicative interaction. Their limited and idiosyncratic social and communicative repertoire results in their failing to participate in most of the play-based learning in which typically-developing children constantly engage. Children with autism who have not developed speech are not only verbally impaired, they are also profoundly impaired in understanding nonverbal communication: how to interpret the facial expressions, directions of gaze, tones of voice and gestures of the people around them (Trepagnier, 1996). Children whose speech is not emerging at the expected time need augmentative support in order to begin to gain social interaction experience, and to support efforts to foster their language development.
Many people with autism demonstrate strengths in the area of visuo-spatial and visual memory skills, and clinicians and investigators have long advocated multimodal, and especially visual, support for communication, as is frequently used in the TEAACH program (Mesibov, 1995; Helms Tillery et al., 2003). The descriptively-named Picture Exchange Communication System or PECS, (Bondy and Frost, 2001) makes use of the autistic child's mobility to build interaction into the use of the technique, and there is some evidence that its use can have beneficial effects on the child's development (Bondy and Frost, 1995; Charlop-Christy et al., 2002). Printed materials too can appeal even to very young communicatively-impaired children with autism, with positive effects on development of literacy skills (Koppenhaver, 2003). Literacy is important, as it is to any individual, and the more important if speech impairment is severe, since it opens the door to spelling-based communication. Families of children with autism face a myriad of divergent information. They must make life-affecting decisions on the basis of woefully inadequate information, both in regard to the education, management and treatment of their child and in regard to the particular issues involved in communication support. The desperate nature of the problem and the paucity of research have combined to create a vacuum into which many unsubstantiated "treatments" have flowed. Recommended guidelines for augmentative support, similar to the guidelines for autism treatment in general (Simeonsson et al., 1987; Dawson and Osterling, 1997), include intensive intervention that begins as early as possible, involves the family, and pays special attention to generalization across partners and settings (Beukelman and Mirenda, 1998).
Communication rate: As noted above, communicating by means of augmentative techniques is terribly slow relative to speech. While the disparity is perhaps most acutely felt by individuals who have had to turn to AAC because of the deterioration of their own motor capabilities, it is a problem for anyone who is attempting to join the flow of human social and communicative interaction by means of a communication device (Goodenough-Trepagnier et al., 1984; Todman and Rzepecka, 2003). This is, of course, the reason for storing pre-constructed messages, since such messages can, in principle, be produced at a normal conversational rate. Investigators have developed numerous strategies for accelerating communication; these have included populating the device's vocabulary, or "selection set" with items chosen for their frequency of occurrence in combination with each other (Goodenough-Trepagnier and Prather, 1981; Goodenough-Trepagnier et al., 1982); using transitional probabilities of letters to "guess" the word once an initial letter or letters have been entered (Koester and Levine, 1994; Hunnicutt, 2001); using multi-letter keys such that the software "disambiguates" by referring to transitional probabilities and a dictionary look-up (Minneman, 1985) and a variety of attempts at mnemonic storage and retrieval schemes. Besides choosing what items should be offered in the device's "selection set", attention is also given to where they should be placed, in order to make operation of the device as easy and rapid as possible (Levine and Goodenough-Trepagnier, 1990). Whatever the technique, the inherent flaw remains, that communicators are being asked to use their residual, often impaired, motor control to compensate for their motor speech impairment. The challenge of finding some way around this problem in order to achieve responsive communication at conversationally acceptable rates still stands.
Mental load: The additional cognitive demands that device operation places on the communicator are a problem not only for people with cognitive disabilities but for all augmentative users. A useful analogy might be that of speaking a language one does not know very well. It is not difficult to imagine that passing an interview, meeting a new colleague or communicating in an emotionally fraught interaction would be all the more difficult if one had to do so using a language one does not know well. Investigators recognize and are striving to address the need to minimize demands on working memory and attention, so that the augmentative technique can become "second nature" to the communicator (Goodenough-Trepagnier, 1994; Hunnicutt, 2001).
Lifelong use: In the communication history of most children and adults with persistent severe speech impairment, there are stages: first augmentative systems tend to be picture-based, and later ones alphabet-based, with possibly intervening stages using symbols and combinations of all three. To use again the analogy of second language, it is as if the child's education were begun in Chinese, which was then supplanted by Japanese and later still by English. Non-disabled keyboard users have resisted the relatively minor alteration of replacing the QWERTY keyboard arrangement (designed to prevent tangling the typewriter's keys) with the potentially more rapid Dvorak system. Unlearning is undesirable. Yet children with severe communication disorders are as a matter of standard practice asked to give up their communication techniques to move on to techniques that are presumed to be better. Indeed it is the case that the individual who can use written language should have the opportunity to do so, since it is so much more powerful and economical than pictures. The challenge here, then, is to meet the need for conversational rate and transparency and add to it the goal of continuity: devise a way to meet the child's need for more powerful communication and at the same time reduce and ideally obviate the need to learn and then give up earlier, less ultimately useful techniques. This goal also implies providing more powerful and effective communication media for the earliest stages of communicative life, a challenge that is perhaps the area of greatest need, since our failure to meet it deprives the individual of developmental opportunities that will not recur.
It is conceivable that by the time these words are published there will be a communication device on the market that the communicator can operate by means of electrical events in his or her own brain. At present several groups of investigators around the world are pursuing this goal, as Wolpaw and colleagues (Wolpaw et al., 2002) describe. This work encompasses several different types of brain signals, including evoked potentials in response to the appearance of significant events (e.g., the illumination of an intended letter on a letter matrix); and brain rhythms that change as a function of preparation for movement. Typically, the brain activity of interest is sensed by electrodes in contact with the communicator's scalp. Since the electrodes receive innumerable signals simultaneously, signal processing is required to extract the pertinent information. The limiting factor here is not computing power and speed: the signal processing is carried out in real time. Not surprisingly, it is the interface of the user to the device that continues to be problematic. In virtually all current brain interfaces, control is by means of a two-state switch, adequate only for scanning of some kind, a far from satisfactory means of device operation. Even this level of capability can entail large amounts of training. Furthermore, despite the training, some individuals, including individuals who are not disabled, are unsuccessful. Questions remain as to the extent to which individuals with movement disorders of various types would be capable of controlling signals from somatosen-sory areas of the brain. It may be that combining information about the type of signal with information about the time relationship between device events and brain events (Schalk et al., 2000) will bring added power to this intriguing interface approach. While at present there are usually more easily acquired techniques with similar power to which a person with severe motor disability can have recourse, recent animal work, in which trained monkeys have rapidly attained the ability to control events on a monitor using a brain interface, strongly suggest that we will have significantly improved interfaces to offer to people with disabilities in the not-too-distant future (Wolpaw et al., 2000; Helms Tillery et al., 2003).
Recognition of the human right to communication and the many ways in which communication can be supported, whatever the nature of the individual's profile of abilities and deficits, continues to spread rather gradually through the community of healthcare providers, human service workers and educators, and even more slowly among the general public. This is troubling because it means that there are children who are losing precious years of communicative, social and intellectual development that they will not recoup, children learning to be helpless or resorting to disruptive behaviors for want of a more effective communication modality, bright minds frustrated by the lack of a way to convey their thoughts and individuals experiencing needless isolation during periods of illness. There is no doubt that effort must be directed to increasing professional and public awareness of AAC.
It must also be recognized that there are knowledge gaps in the AAC "field". The field is relatively new, eclectic and not as well anchored in evidence as we would wish. The problem is compounded by the fact that many health professionals have had little experience with this domain, and little or no formal training. This situation will undoubtedly improve. Consumers and family members will, however, for some time to come, need to exercise careful judgment, whether networking with other affected families, consulting with specialists or trying out products. One of the most useful things an advocate can do is to spend time interacting with other consumers who have similar capabilities and needs, to see how they fare with their AAC supports. Another is to ask questions, and not to be content with unsatisfying answers.
Communication devices can contribute in major ways to the well-being of members of society who would otherwise be virtual prisoners in their own bodies. It could contribute considerably more, and may do so in the near future, in order to enable these citizens to express their full cognitive, social and emotional potential.
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