Page 196 - Handbook of Electronic Assistive Technology

184 HANDBOOK OF ELECTRONIC ASSISTIVE TECHNOLOGY

pneumatic control, allowing the user to inhale or ‘sip’ to move the scan forward and
exhale or ‘puff’ to make a selection when the desired item was highlighted. Similar sys-
tems allowed the use of light pointers attached to a body part with reliable movement,
which could be targeted at photosensitive cells to make selections (Vanderheiden, 2002).
In the 1960s, 1970s and 1980s, several companies focusing on the manufacture of AAC
devices began to appear, including Prentke Romich (1969), Toby Churchill Ltd (1973)
and Dynavox (1982).
Most early AAC systems focused on the use of traditional orthography and were designed
to meet the needs of literate users. In the 1960s and 1970s, the use of graphic symbols was
introduced to facilitate access to AAC for those with greater levels of intellectual disability.
Beginning with the use of highly ideographic symbol systems such as Blissymbols, where
a range of base symbols can be combined to produce new concepts and more complex
language, the use of graphic symbols has expanded to include pictogram-based systems
such as the Picture Communication Symbols and Widget Literacy Symbols. These symbol
libraries tend towards presenting a more pictorial representation of an object or action
(Fig. 7-1).
It has been argued that, while perhaps less flexible than the use of Blissymbols, picto-
grams are more transparent and therefore easier for children and people with intellectual
disabilities to learn. However, it has been proposed that existing pictograms still differ sig-
nificantly from children’s representations of early emerging language concepts (Light and
Drager, 2007) and that the learning needs could be further reduced by redesigning symbol
sets. In recent years, several sets of open source symbols offered under Creative Commons
licensing (such as ARASAAC symbols of the Mulberry symbol set) have appeared, along
with culturally specific symbols such as those from the Tawasol symbol set. A large library
of open source symbols can be found at www.opensymbols.org.
Technological developments in the field of AAC have tended to follow the develop-
ment and spread of personal computer (PC) technologies. In the 1980s and 1990s, PC
devices became smaller, more powerful and more affordable, with these changes being
reflected in the field of AAC. More recently, with the wide availability of tablet PC tech-
nology, AAC systems have become smaller, lighter and are now often based on commer-
cially available technology. While there still exists some debate regarding the pros and
cons of using mainstream technology as opposed to systems designed from the bottom
up, specifically for AAC (Griffiths and Price, 2011; McNaughton et al., 2013), the field
has generally embraced the move toward bespoke software running on mainstream or
customised hardware. Changes and developments in access technology have also meant
that high-tech AAC devices can now be controlled in a wide variety of different ways. In
particular, the development of eye-gaze access technology, where the movement and
rest of a user’s eyes are converted into cursor control, has allowed access to AAC systems
for some users who previously may have had no physical means of interfacing with and
controlling technology.
As AAC grew and developed, several organisations emerged to promote awareness
and understanding, and to support people using AAC, clinicians and researchers in the