According to the National Research Council (2001), approximately one-third to one-half of children and adults with autism do not use speech functionally. When verbal speech or gestures are insufficient for an individual with autism to communicate their needs and wants, augmentative or alternative systems of communication (AAC) are developed. An augmentative system is a supplemental service when verbal speech is unintelligible, when vocabulary is not complex, or when spontaneous language is lacking. An alternative system is a primary means of communication when verbal speech is not present.
If an ACC system is recommended for an individual with autism, two common questions often follow this recommendation:
- Which AAC systems are most effective towards functional communication in people with autism?
- Which system, if any, will facilitate the development of verbal speech?
This article will define common AAC systems currently in use with individuals with autism and will briefly review the state of the literature in providing answers to the above questions.
What AAC Systems are Available?
AAC systems are generally grouped into two categories: “unaided” and “aided” systems. Unaided systems are those that don’t require any extra materials to use, such as American Sign Language (or other developed systems of sign). Aided systems are those that do require equipment or materials to implement. Examples of aided systems are picture or symbol systems (such as PECS, Bliss Syms, photographs) and vocal output devices (VOCAs). VOCAs are computerized systems that use buttons, switches or touch screen technology with synthesized voice output.
All of these systems are used with individuals with autism and different instructional methodologies often have a preference for one over the other. Programs using applied verbal behavior instruction typically focus only on sign language as AAC, with the rationale (among others) that motor planning skills needed to produce the sign will facilitate production of verbal approximations. TEACCH models typically use PECS and other pictures for AAC, with the rationale that individuals with autism often need visual cues and support to understand their environment. By way of full disclosure, the authors of this article do not have a preference or theoretical bias towards any AAC system and have used all effectively.
Effectiveness of AAC Systems
The “good” news regarding effectiveness of AAC systems towards functional communication is that all types of AAC have been demonstrated to be useful as modes of communication in individuals with autism. There is a wide body of literature suggesting that AAC can be extremely effective under certain conditions. Some of these conditions include:
- An AAC is effective if the physical response effort required to produce the desired result with the AAC is less than the effort required to produce the result by other behaviors (Horner and Day, 1991).
- A visual AAC (i.e. use of pictures/symbols) is more effective the closer the pictures/symbols resemble their real-world counterparts (this is referred to in the literature as “iconicity”) (Fuller and Stratton, 1991).
An AAC is effective only to the extent that the communication is intelligible to others and can produce the desired result (Schlosser, 2003).
The “bad” news, however, is that the research still has a long way to go in determining whether one type of system or another is more effective in meeting communication goals in individuals with autism on the whole. Very few studies have compared unaided to aided systems directly, and less have focused on only individuals with autism. The research has not at all addressed the question of “what are the characteristics of an individual that make one type of system potentially more effective than another?”
When choosing an AAC system for an individual, practical concerns such as portability, durability, and vocabulary needs and space will generally take precedence over research-based suggestions. Also, student interest in and motivation to use the system is critical to its success, regardless of how the research supports its use.
Effect of AAC on Verbal Speech
If an AAC system is recommended as an augmentative system (rather than alternative), a primary concern is how that system will affect the person’s acquisition and use of any verbal speech that is present. It is an occasional assumption that the AAC will be taught or used at the exclusion of verbal speech and that the child will lose whatever verbal speech is present. We have had parents who don’t want their children to use AAC because they are afraid of this result. In order to program effectively for our students’ communication needs, we have had to develop a response to this fear.
In general, results in the scientific literature suggest that total communication approaches result in faster and more complete vocabulary acquisition that does speech alone (Mirenda 2003). There is a considerable body of research in which total communication was compared with speech alone and/or AAC alone to teach receptive and/or expressive vocabulary with children with autism who have limited or no functional verbal speech. Layton & Watson (1995) said that communicating with sign may transfer to that spoken word after a child has learned approximately 200 signs and/or starts to chain together two or more signs. Bondy & Frost (1994) said that verbal speech tended to develop with PECS as an AAC after the children were able to use 30-100 symbols.
What this means, is that AAC systems may facilitate the development of verbal speech as long as the instructors expect and reinforce verbal approximations at the same time as AAC production. Although we cannot guarantee for any individual student that AAC will automatically result in improved verbal production, we can be confident that AAC will not impede the development of this. It is important that speech pathologists, teachers, therapists, parents, and others when they teach AAC are also requiring the student to produce some verbal sound and continue to shape that towards a more understandable vocabulary. It is also critical that individuals responding to AAC or speech production are similarly required to respond positively to the students’ communication attempts.
Cindy Alterson, PhD, BCBA, is the principal and program director of the Devereux Millwood Learning Center. Jennifer Naughton Basch, MS, CCC/SLP, is a consulting speech pathologist at the Devereux Millwood Learning Center.