Page 195 - Handbook of Electronic Assistive Technology

Chapter 7 • Alternative and Augmentative Communication 183

Early AAC assessment and provision operated on a candidacy model, in which it was
believed that a group of prerequisite motor, cognitive, language and social skills must be
present in an individual for the introduction of AAC to be considered. For example, before
the advent of dynamic screen devices capable of displaying multiple pages of graphic sym-
bols, AAC systems capable of voice output were generally considered only for individuals
with good literacy skills. With the advent of portable dynamic screens and other similar
technological advances and the increased focus on AAC as a specific field, this thinking has
changed and today AAC is considered as a way to support individuals with a broader range
of disabilities. Changes in disability legislation and awareness have also played a part in
AAC being implemented for a broader range of people (Hourcade et al., 2004). In 2003, the
National Joint Committee for the Communication Needs of Persons with Severe Disabilities,
an American multiprofessional committee, proposed that the candidacy model and the
determination of eligibility based on predetermined criteria ‘violate recommended practice
principles by precluding consideration of individual needs’. Today, it is common practice
that ‘eligibility for communication services and supports should be based on individual
communication needs’, as suggested by the committee (Brady et al., 2016).
The use of multifunctional devices has also meant that AAC systems can also support
people with a range of functions, including communication, access to education, play and
leisure activities (Griffiths and Price, 2011; Morris and Bryen, 2015). Increased research
activity has also helped to change the perspective on whom AAC systems are provided for
and the impact they have. For example, one concern was that the provision of an AAC sys-
tem would slow or halt any progress that would be made with natural speech in children
with developmental disabilities. This has been shown not to be the case: in fact a system-
atic review conducted in 2006 demonstrated that an increase in the production of speech
was reported in 24 of 27 included cases (Millar et al., 2006). With reference to adults with
aphasia, results from single case and small group design studies indicate that people with
post-stroke aphasia show improvements when a high-technology AAC is used to enhance
communication. Studies have involved people with different types of aphasia, varying
degrees of severity and several types of AAC (Russo et al., 2017).
While unaided forms of AAC such as sign language can trace their history back as
far as the 16th and 17th centuries, and the use of writing for people with well-devel-
oped literacy but no functional speech also has a long history, formal systems of aided
communication are a much more recent innovation. Low-tech communication boards
(printed arrays of letters or phrases for selection by pointing with a finger or stylus)
were first manufactured for use in the 1920s (Vanderheiden, 2002). High-tech AAC
systems began to emerge in the 1960s, focusing initially on the adaptation of exist-
ing technologies for literate users. Beginning with comparatively simple adaptations
such as a head pointer or a keyguard for a manual typewriter, the development of
specific technologies for people with disabilities allowed access to AAC devices for
an ever-increasing range of clients. An early example, the Patient Operated Selector
Mechanism (POSSUM, 1960), was a typewriter controller that scanned through a set of
symbols which could be selected by using a sip/puff switch – a type of switch that uses