Augmentative and alternative communication

Sign for "interpreter" in Quebec Sign Language

Unaided AAC systems are those that do not require an external tool, and include facial expression, vocalizations, gestures, and sign languages and systems.[16][17] Informal vocalizations and gestures such as body language and facial expressions are part of natural communication, and such signals may be used by those with profound disabilities.[18] More formalized gestural codes exist that lack a base in a naturally occurring language. For example, the Amer-Ind code is based on Plains Indian Sign Language, and has been used with children with severe-profound disabilities, and adults with a variety of diagnoses including dementia, aphasia and dysarthria.[19] The benefits of gestures and pantomime are that they are always available to the user, usually understood by an educated listener, and are efficient means of communicating.[20]

In contrast, sign languages have a linguistic base and permit the expression of an unlimited number of messages.[19] Approaches to signing can be divided into two major categories, those that encode an existing language, and those that are languages in their own right.[21] In the United States of America, Signing Exact English may be considered the most widely used example of the former and American Sign Language as a common example of the latter.[21] Signing is used alone or in conjunction with speech to support communication with individuals with a variety of disorders.[22] The specific hand shapes and movements of sign and gesture require an individual to have adequate fine motor and motor planning skills.[16][23] Sign languages require more fine-motor coordination and are less transparent in meaning than gestural codes such as Amer-Ind; the latter limits the number of people able to understand the person's communication without training.[24][25][26]

This communication board, showing a food category, is a low-tech AAC aid.

This speech generating device, showing available categories in a grid layout, is a high-tech AAC aid.

An AAC aid is any "device, either electronic or non-electronic, that is used to transmit or receive messages";[8] such aids range from communication books to speech generating devices.[16] Since the skills, areas of difficulty and communication needs of AAC users vary greatly, an equally diverse range of communication aids and devices is required.[27]

Low-tech communication aids are defined as those that do not need batteries, electricity or electronics. These are often very simple communication boards or books, from which the user selects letters, words, phrases, pictures, and/or symbols to communicate a message.[28] Depending on physical abilities and limitations, users may indicate the appropriate message with a body part, light pointer, eye-gaze direction, or a head/mouth stick. Alternatively, they may indicate yes or no while a listener scans through possible options.[29]

High-tech AAC aids permit the storage and retrieval of electronic messages, with most allowing the user to communicate using speech output.[30] Such devices are known as speech generating devices (SGD) or voice output communication aids (VOCA).[31] A device's speech output may be digitized and/or synthesized: digitized systems play recorded words or phrases and are generally more intelligible while synthesized speech uses text-to-speech software that can be harder to understand but that permits the user to spell words and speak novel messages.[31][32]

High-tech systems may be dedicated devices developed solely for AAC, or non-dedicated devices such as computers that run additional software to allow them to function as AAC devices.[30][33] They may be static or dynamic in form. Static communication devices have symbols in fixed positions on paper overlays, which are changed manually. To increase the vocabulary available, some static devices have multiple levels, with different words appearing on different levels.[34] On dynamic AAC devices, the user can change the symbols available using page links to navigate to appropriate pages of vocabulary and messages.[35][36]

High-tech devices vary in the amount of information that they can store, as well as their size, weight and thus their portability.[37] Access methods depend on the abilities of the user, and may include the use of direct selection of symbols on the screen or keyboard with a body part, pointer, adapted mice or joysticks, or indirect selection using switches and scanning.[33][38]

Keyboard used to create speech over a telephone using a Text to Speech converter.

Devices with voice output offer its user the advantage of more communicative power, including the ability to initiate conversation with communication partners who are at a distance.[39] However, they typically require programming,[39] and can be unreliable.

High-tech systems can also include keyboard-based solutions that do not require programming with a mix of flexibility, simplicity, and associated reliability. In this case, a keyboard and audio speaker are configured to be create a "talking keyboard" where typed text is spoken directly in an audio speaker. This allows any phrase to be spoken as it is typed using unlimited vocabulary text-to-speech conversion. One simple benefit is that a talking keyboard, when used with a standard telephone or speakerphone can enable a voice impaired individual to have a two-way conversation over a telephone. Game accessibility often utilizes high-tech solutions to allow individuals with disabilities to participate in conversations and use "call outs".

In all cases of use, low tech systems are often recommended as a backup in case of device failure.[33][40][41]

Several reviews have found that the use of AAC does not impede the development of speech in individuals with autism or developmental disabilities, and in fact, may result in modest gains being observed.[91][92] A 2006 research review of 23 AAC intervention studies found gains in speech production in 89% of the cases studied, with the remainder showing no change.[92] A descriptive review looking specifically at Picture Exchange Communication System (PECS) intervention studies found that several studies reported an increase in speech, often during later phases, while one noted little or no effect.[93]

Researchers hypothesize that using an AAC device relieves the pressure of having to speak, allowing the individual to focus on communication, and that the reduction in psychological stress makes speech production easier.[94] Others speculate that in the case of speech generating devices, the model of spoken output leads to an increase in speech production.[95]

Language and literacy have far reaching effects as they facilitate self-expression and social interaction in a variety of settings.[96] Furthermore, literacy fosters independence by providing access to educational and vocational opportunities.[97] Children whose disabilities require AAC often experience developmental delays in language skills such as vocabulary knowledge, length of sentences, syntax, and impaired pragmatic skills.[88] These delays may be due in part to the fact that expressive language is limited by more than the children's own language knowledge. Unlike speaking children, children who use AAC do not always have access to their AAC system, and don't select the content available on the device. These external characteristics may impact language learning opportunities.[98] Most children in this category do not achieve literacy skills beyond that of a typically developing 7–8 year old. [99] Cognitive, language and learning delays contribute to difficulty with literacy development,[88] but environmental factors also play a role. The most literate AAC users often report having access to abundant reading and writing material at home as well as in school during childhood.[100] Studies have shown that many children who use AAC have literacy experiences that are reduced quality, quantity, and opportunity at home and at school as compared to children without disabilities.[97][101][102] Research suggests that with explicit reading instruction, AAC users can develop good literacy skills.[89][90]

According to a 1997 U.S. Census Bureau report less than 10% of severely disabled individuals were employed. Despite the various barriers to employment, some AAC users achieve success in educational endeavours and employment, though often in lower paying jobs.[103][104] Factors that have been found to be related to employment are a strong work ethic and access to AAC technology, the support of family and friends, education, and work skills.[105] Individuals with ALS who use AAC may continue working; factors supporting continued employment include access to AAC, support from employers, governmental programs and others.[106] Employers of AAC users report that skills in time management, problem solving, communication, technology and a good education are important to employers.[107]

Several studies of young adults who had used AAC since childhood report a generally good quality of life, though few lived independently, or were in paid employment.[103][108] The young adults used multiple modes of communication including aided and unaided AAC approaches.[103][109] More positive quality of life outcomes often correlated with better quality of communication and interaction, as well as personal characteristics, family and community support, and excellent AAC services.[103][108][110] Poorer outcomes were related to lack of access to appropriate AAC supports and resources, problems with technology and negative attitudes.[103][110]

Cerebral palsy is a term referring to a non-progressive developmental neuromotor disorder with an upper motor neuron lesion origin.[111] Depending on the location of the brain lesion, individuals with cerebral palsy can have a wide variety of gross and fine motor challenges, including different forms and areas of the body affected. Fine motor planning, control and coordination are often affected.[112] Dysarthria, a speech disorder resulting from neurological damage to the motor-speech system, occurs in an estimated 31% to 88% of those with cerebral palsy. Such individuals may require AAC support for communication. Approximately one half to one third have some degree of intellectual impairment, and visual and hearing problems are also common.[113][114] Gross and fine motor challenges are often of particular concern in accessing an AAC device.[112] Appropriate seating and positioning are important to facilitate optimum stability and movement.[115] Extensive motor training and practice may be required to develop efficient AAC access and use.[116] The trend towards custom-placed sensors and personalized signal processing may assist in facilitating communication for those who are incapable of using other AAC technologies.[117]

Phrases can be recorded onto simple switch-operated AAC devices by a user or carer so that the recording is played when the switch is pressed.

Individuals with intellectual impairments face challenges in developing communication skills, including problems with generalization (the transfer of learned skills into daily activities). They may lack communication opportunities in their daily lives, and responsive communicators who understand their communication methods.[118] AAC intervention for this population emphasizes partner training as well as opportunities for integrated, natural communication.[118] Studies have shown that appropriate use of AAC techniques with children and adults with intellectual impairments can enhance communication skills,[119][120] increase participation in activities,[121] choice-making,[122] and even influence the perceptions and stereotypes of communication partners.[121] In Ireland, a system of manual communication (a simplified sign language) called Lámh is used by those with developmental disabilities, their family, carers and friends.[123][124]

Although most individuals with intellectual disabilities do not have concomitant behavioural issues, problems in this area are typically more prevalent in this population than others.[125] AAC approaches may be used as part of teaching functional communication skills to non-speaking individuals as an alternative to "acting out" for the purpose of exerting independence, taking control, or informing preferences.[118]

Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behaviour. Typically there is particular difficulty acquiring expressive communication skills.[91][126] People with autism have been found to have strong visual processing skills, making them good candidates for an AAC approach.[127] AAC intervention in this population is directed towards the linguistic and social abilities of the child,[128] including providing the person with a concrete means of communication, as well as facilitating the development of interactional skills.[91][129]

Explains percentage of people who require AAC Devices.[130][131][132]

AAC systems for this population generally begin with communication boards and/or object or picture exchanges such as the Picture Exchange Communication System (PECS).[129] A 2009 descriptive review provided preliminary evidence that PECS is easily learned by most autists, provides communication to those with little or no functional speech, and has some limited positive impact on social interaction and challenging behaviours.[93] A study that compared the use of a speech generating device to a picture exchange system found that both were reasonable options for autistic children, as the ease and speed of acquisition of each system was similar.[133]

Developmental verbal dyspraxia, also known as childhood apraxia of speech, is a developmental motor speech disorder involving impairments in the motor control of speech production.[134] The speech of a child with developmental verbal dyspraxia may be unintelligible to the point that daily communication needs cannot be met. A child with developmental verbal dyspraxia often experiences great amounts of frustration, so AAC can be a strategy to support communication alongside more traditional speech therapy to improve speech production.[135]

A wide variety of AAC systems have been used with children with developmental verbal dyspraxia.[136] Manual signs or gestures are frequently introduced to these children, and can include the use of fingerspelling alongside speech. Manual signs have been shown to decrease errors in articulation.[135] Aided AAC systems typically include communication boards and speech generating devices.[136] A multimodal approach is often used, with several AAC approaches introduced so that the child can take advantage of the most effective method for a particular situation.[135]

Traumatic brain injury can result in severe motor speech disorders; dysarthria is the most common such disorder, accounting for roughly a third of all cases.[137] Depending on the stage of recovery, AAC intervention may involve identifying consistent communication signals, the facilitation of reliable yes/no responses to questions, and the ability to express basic needs and answer questions. Individuals who do not recover natural speech to a degree sufficient to meet their communication needs typically have severe impairments related to cognition.[138] Difficulties with memory and learning new skills may influence AAC choices; well-established competencies such as spelling may be more effective than AAC systems that require navigation through multiple pages to access information.[138]

Aphasia is the result of damage to the brain's language centres affecting production, comprehension, or both, and can cause severe, chronic language impairment.[139] Individuals with aphasia often communicate using a combination of speech, gestures, and aided communication; the proportion of each may change as the person recovers, and depends on the context and the individual's skills.[140]

Depending on their language and cognitive skills, those with aphasia may use AAC interventions such as communication and memory books, drawing, photography, written words, speech generating devices and keyboards.[139] Visual scene displays have been used on communication devices with adults who have chronic, severe aphasia; these feature photos of people, places or events that are meaningful to the individual and facilitative of communicative interaction.[139] Approaches such as "Supported Conversation for Adults with Aphasia" train the communication partners to use resources such as writing key words, providing written choices, drawing, and using items such as photographs and maps to help the individual with aphasia produce and comprehend conversation.[141][142] Communication boards can be very helpful for patients with aphasia, especially with patients who are very severe. They can be produced at a very low tech level, and can be utilized by patients to point to pictures/words they are trying to say. Communication boards are extremely functional and help patients with aphasia communicate their needs.

Strokes that occur in the brainstem may cause profound deficits, including locked-in syndrome,[143] in which cognitive, emotional and linguistic abilities remain intact but all or almost all voluntary motor abilities are lost.[144] Most people affected by this type of stroke rely on AAC strategies to communicate, since few recover intelligible speech or functional voice.[145] The AAC strategies used vary with the individual's preferences and motor capabilities which may change over time. As eye movements are most likely to be preserved, eye blinks are frequently used for communication.[144] Low-tech alphabet boards are often introduced immediately to provide the individual with basic communication. Partner-assisted scanning may be used, in which the AAC user signals when the desired letter is named by a communication partner. When vertical and horizontal eye movements are functional, a transparent alphabet board may be used in which the AAC user looks at the desired letter and this is acknowledged by the communication partner.[144] Individuals with locked-in syndrome have difficulty using high-tech devices due to issues with motor control, vision, memory, alertness and linguistic ability.[144] In particular, a voluntary, reliable and easily controlled muscle movement is necessary to access such a device, such as head, jaw, hand or finger movements.[144] In some individuals, intensive practice, even long after the initial stroke, has been shown to increase the accuracy and consistency of head movements,[145] which can be used to access a communication device.[144]

Stephen Hawking, a noted physicist with ALS who used AAC

Amyotrophic lateral sclerosis (ALS) or motor neuron disease (MND) is a progressive condition which leads to weakness and eventual paralysis. Approximately 75% of people with ALS are unable to speak by the time of their death.[146] In a procedure known as voice banking, people with ALS may digitally record words and phrases while still able to do so, for later inclusion in a communication device.[147] AAC systems used typically change over time depending on severity of speech impairment, physical status, and the individual's communication needs.[148] Use of augmentative communication strategies generally begins when speaking rate drops to 100 words per minute.[149] In the early stages, AAC may consist of using an alphabet board to cue the listener to the first letter of the word being spoken, and may be used with those less familiar with the individual. In the later stages, AAC often becomes the main communicative method, although familiar conversation partners may still understand some spoken words.[150] Since cognition and vision are typically unaffected in ALS, writing-based systems are preferred to graphic symbols, as they allow the unlimited expression of all words in a language.[150]

The method of access to a communication device depends on the type and severity of the disease. In the spinal form of ALS, the limbs are affected from the onset of the disease; in these cases a head mouse or eye tracking access may be used initially.[151] In the bulbar form, speech is affected before the limbs; here handwriting and typing on keyboard-style devices are frequently the first forms of AAC.[152] AAC users may change access methods as the disease progresses. Low-tech systems, such as eye gazing or partner assisted scanning, are used in situations when electronic devices are unavailable (for example, during bathing) and in the final stages of the disease.[152]

Keyboard text-to-speech generating device for literate users with adequate fine motor control

Parkinson's disease is a progressive neurological condition[153] in which dysarthria may develop later in the progression of the disease.[154] Some individuals eventually lose all functional speech.[155] AAC approaches are generally used to supplement and support natural speech.[155] A portable amplifier, for example, may be used to increase the volume of speech and thus its intelligibility. The individual may be taught to point to the first letter of each word they say on an alphabet board, leading to a reduced speech rate and visual cues for the listener to compensate for impaired articulation. Entire words can be spelled out if necessary.[155] In users that have reduced range and speed of movement, a smaller than usual selection display may be preferred.[155] High-tech AAC keyboard speech-generating devices are also used; keyguards may be required to prevent accidental keystrokes caused by the tremor typical of the disease.[155] Factors affecting AAC use in Parkinson's disease include motor deficits and cognitive changes; the latter may result in unawareness of their problems with spoken communication.[153][156]

Dysarthria is the most common communication problem in individuals with multiple sclerosis (MS), however, significant difficulties with speech and intelligibility are uncommon.[157][158] Individuals with MS vary widely in their motor control capacity and the presence of intention tremor, and methods of access to AAC technology are adapted accordingly. Visual impairments are common in MS and may necessitate approaches using auditory scanning systems, large-print text, or synthetic speech feedback that plays back words and letters as they are typed.[159]

Dementia is an acquired, chronic, cognitive impairment characterized by deficits in memory and other cognitive domains.[139][160] Communication impairments are partly attributed to memory deficits,[160] and AAC intervention may be used to compensate for deficits and to capitalize on the person's strengths, such as the ability to recognize material they cannot recall.[161] Low-tech devices are generally preferred, such as memory books that include autobiographical information, daily schedules, photographs, and reminders or labels.[161] Several studies have shown positive outcomes in the amount of on-topic conversation and the length of interaction with these approaches.[162][163][164] The gains were maintained four months after the training in the use of the memory aids had ceased.[164] High-tech devices with voice output have been found to be less effective; in one study devices resulted in limited topic elaboration/initiation, reduced output and heightened distraction.[160] AAC is also used to enhance the comprehension of those with dementia. The use of augmented listening strategies, such as identifying topics of conversation with pictures, improves the conversational skills of individuals with dementia.[161]

Facilitated communication is a scientifically discredited technique[184] that attempts to aid communication by people with autism or other communication disabilities who are non-verbal. The facilitator guides the disabled person's arm or hand and attempts to help them type on a keyboard or other device.[185]

While advocates of the technique claim that it can help disabled people communicate, research indicates that the facilitator is the source of the messages obtained through FC, rather than the disabled person. The facilitator may believe they are not the source of the messages due to the ideomotor effect, which is the same effect that guides a Ouija board.[186][187] Studies have consistently found that FC is unable to provide the correct response to even simple questions when the facilitator does not know the answers to the questions (e.g., showing the patient but not the facilitator an object).[188] In addition, in numerous cases disabled persons have been assumed by facilitators to be typing a coherent message while the patient's eyes were closed or while they were looking away from or showing no particular interest in the letter board.[189]

Facilitated communication has been called "the single most scientifically discredited intervention in all of developmental disabilities".[190] Some promoters of the technique have claimed that FC cannot be clearly disproven because a testing environment might cause the subject to lose confidence.[191] However, there is a scientific consensus that facilitated communication is not a valid communication technique, and its use is strongly discouraged by most speech and language disability professional organizations.[192] There have been a large number of false abuse allegations made through facilitated communication.

The rapid prompting method (RPM), is a pseudoscientific technique that attempts to aid communication by people with autism or other disabilities to communicate through pointing, typing, or writing.[193][194] Also known as spelling to communicate,[195] it is closely related to the scientifically discredited[196][197][198] technique of facilitated communication (FC).[193][199][200] Practitioners of RPM have failed to assess the issue of message agency using simple and direct scientific methodologies, saying that doing so would be stigmatizing and that allowing scientific criticisms of the technique robs people with autism of their right to communicate.[194][201] The American Speech-Language-Hearing Association has issued a statement opposing the practice of RPM.[202]

Soma Mukhopadhyay is credited with creating RPM, though others have developed similar techniques, known as informative pointing or alphabet therapy.[193] RPM users report unexpected literacy skills in their clients,[194] as well as a reduction in some of the behavioral issues associated with autism. As noted by Stuart Vyse, although RPM differs from facilitated communication in some ways, "it has the same potential for unconscious prompting because the letter board is always held in the air by the assistant. As long as the method of communication involves the active participation of another person, the potential for unconscious guidance remains."[201]

Critics warn that RPM's over-reliance on prompts (verbal and physical cuing by facilitators) may inhibit development of independent communication in its target population.[203] As of April 2017, only one scientific study attempting to support Mukhopadhyay's claims of efficacy has been conducted, though reviewers found the study had serious methodological flaws.[203][204] Vyse has noted that rather than proponents of RPM subjecting the methodology to properly controlled validation research, they have responded to criticism by going on the offensive, claiming that scientific criticisms of the technique rob people with autism of their right to communicate,[201] while the authors of a 2019 review concluded that "until future trials have demonstrated safety and effectiveness, and perhaps more importantly, have first clarified the authorship question, we strongly discourage clinicians, educators, and parents of children with ASD from using RPM."[205][206]