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A. Direct Selection
Direct selection is difficult to define without using
those very words. So, the technical definition is somewhat convoluted:
the individual "specifically indicates the desired item in the selection
set, without any intermediary steps." (Dowden & Cook, 2002).
But, this is just a complex way of saying that the individual points
directly at the item without having to wait for options to be presented.
Pointing can be done with the finger or hand or toe, or with any number
of pointing tools or even by handing a symbol to the partner. In all cases,
he makes his selection directly from
the existing options which are available in front of him.
Questions to vendors:
What variations on key shape and size are possible
in a given device?
Can the amount of pressure required to activate
keys be modified?
- What accessories are available to improve direct selection (e.g.
keyguard, arm rest, etc.)?
There are five types of direction selection methods used for AAC devices
- Pointing with physical contact and force
- Pointing without physical contact
- Pointing with contact and no force
- Pick up and exchange
- Voice recognition or speech input
1. Pointing with physical contact and force
In this method, a user points and presses to select an item using a finger,
the whole hand, a headwand, mouthstick or even a toe.
Selecting a symbol using a finger.
Photo courtesy of Words+,
2. Pointing without physical contact
You can point without actually touching an object to select it. Some
examples of this method are
- eye gazing at an item (requires a partner to read the gaze)
- using a light pointer
- using an infrared pointer
Here is a system based on infrared sensors and a reflective dot
on the forehead:
(click image to enlarge)
Headmouse, using infrared sensors
Origin Instruments Corporation
A variation on this approach is an eye-gaze board, where the user
simply looks at the item he or she wants to indicate. Many companies
have sought to make technology that's accessible via eye gaze for
communication. The reasoning is simple: The military has long had
eye-gaze operated systems for their purposes, why not for AAC?
Here's a system that functions via eye gaze as interpreted by the
Eye-Gaze Communication System
LC Technologies, Inc.
Unfortunately, the clinical application of eye-gaze technology for
face-to-face communication (as opposed to computer access) isn't so
straightforward. This is true for several reasons:
- Eye gaze requires that the overall position of the eyes remains
stationary or that the system be recalibrated with each move of the
head. This is extremely difficult in some motor impairments.
- The computer screen has to be placed directly in front of the user,
which interferes with face-to-face interaction between the AAC user
and the partner. This may be extremely disturbing to some individuals,
particularly those with degenerative conditions who are facing the
end of life.
3. Pointing with contact and no force
Some people have the ability to touch items but don't have much physical
strength or endurance. Others may not have the fine motor control needed
to choose a small button or item. For both types of individuals, AAC
devices that don't rely on pressure may answer their needs, for example
a device with a touch screen:
The DynaVox 3100
DynaVox Systems, Inc.
In other cases, it is simply not necessary to push to select an item.
For example, a communication notebook requires pointing but no pressure.
(click to enlarge)
4. Pick up and exchange
Few textbooks recognize this as a method of direct selection, but Picture
Exchange Communication Systems (PECS) should be seen in that light. There
are some individuals who benefit more from a method of communication that
highlights communication as an "exchange" between two people.
The Picture Exchange Communication System (PECS) is the best-known and
most well developed system of this type. However, this access method may
be considered without use of the entire PECS system.
The Picture Exchange Communication System
Pyramid Educational Corporation
5. Voice Recognition or Speech Input
Beukelman and Mirenda (1998) describe one additional form of direct selection:
voice input or speech recognition. Able-bodied individuals are familiar
with this technology in hands-free cell phones installed in expensive
automobiles; the individual says something equivalent to "phone,"
"call," or "office," and the phone dials his or her
secretary. This isn't yet a method of direct selection for AAC users because
technology hasn't overcome the inconsistencies that are characteristic
of most speech impairments. However, the time will come when even the
most dysarthric individual will be able to speak commands and then have
the device produce intelligible speech output.
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