For people with mobility
impairment, computer technology provides an opportunity to gain independence in
daily living and working activities. With modifications a computer can become
accessible for an individual with a disability affecting motor control.
Because mobility impairments differ in degree of severity, it is necessary to
consider all areas of needs when choosing a computer. Included in the group of
persons with mobility impairments are more than 238,000 quadriplegics in the
U>S> who can benefit from modifications and alternatives to standard
keyboards and PC devices. Among the needs to consider are degrees of mobility,
positioning, endurance and communication.
Some individuals need modifications to standard computer equipment. Others may
need to replace an input device or add software to tailor the computer to their
specific needs.
HOW COMPUTERS HELP PERSONS WITH MOBILITY IMPAIRMENTS
Modifications and Alternatives to Standard Keyboards.
Some people with physical disabilities can use a standard computer keyboard,
but may type with one hand, one or two fingers, a head pointer, a mouth stick,
a hand stick or with reduced motor control. For these situations, there are software
and hardware modifications that simplify keyboard operations.
Persons who have reduced motor control or who use a head stick or mouth stick
to press the keys may need a way to prevent accidental keystrokes. A key gaurde
is a keyboard overlay with holes positioned over each key. It helps the user to
stabilize finger, hand or stick movement and to select a key without
accidentally activating other. Standard IBM keyboards have a built-in
auto-repeat feature. If a key is held down long enough, it begins repeating and
extra characters may be typed. Software programs are available to slow down or
eliminate this feature. Single-finger programs allow the user to change the
operation of keys such as SHIFT, CONTROL and ALT so that two or more keys do
not have to be pressed simultaneously. Key latches that toggle off and on may
be used to lock keys temporarily. For the typist able to use only one hand,
keyboard redefinition programs allow each key to be reassigned and permit the
keyboard layout to be redesigned. For example, keys may be reassigned to
distribute the typing load more evenly between the fingers on one hand, and
keyboards with layouts for right- or left-handed typing are available.
In some instances, substitutes or replacements for the standard keyboard may be
required. An individual who can press on a flat surface, but cannot depress
keys, may be able to use a membrane keyboard. There are expanded keyboards with
larger keys for those who can target only large areas and miniature keyboards
for those with an extremely limited range of movement of their limbs. Some keyboards
may be tailored to allow single keystrokes to produce frequently used words or
phrases.
Alternative Input Methods
A keyboard is the most commonly used method of providing input to a PC> For
an individual with a motor control impairment who may not be able to use a
keyboard effectively with adaptations such as those just described, other input
methods have been developed. The computer accepts characters or commands coming
from these alternative input methods just as if they were coming from the
computer's standard keyboard.
When choosing an alternative method, one should ensure the method is compatible
with all software applications to be used; such as word processing programs
database programs and educational programs. One input method uses a switch to
enter the same data that would be keyed. Almost any motion of any part of the
body activates a wide variety of switches. A switch adapts to user's abilities
- the voluntary actions that the user can reliably control. For example, a switch
may be turned on or off by sipping and puffing on a tube, wrinkling the
eyebrows or making contact with a metal plate. A switch interface, which can be
a software program or hardware device, acts as the link between the switch and
the computer.
One technique for operating a computer with a switch is scanning. The user
selects the desired characters or words from the computer display or a separate
panel. With scanning, a cursor or highlighted area moves repeatedly form one
character (or group of characters) to the next. Activating a switch enters the
selection into the computer as if it had been keyed. Another technique using a
single or dual switch is Morse Code. The switches connect to an adapter that
translates the pattern of dots and dashes into standard keyboard signals. The
advantage of Morse code is that it may be faster than scanning for some people
and does not require a separate panel or occupy a part of the computer screen.
With a direct selection method, the user points to target items through a
single action such as eye gaze, head pointer or light beam. The characters
selected may be displayed on the computer terminal or on a separate panel.
Voice Recognition is an alternative input method by which a computer accepts a
spoken command. Previously stored voice patterns are compared with the incoming
sound. With some voice recognition systems, the person using the system must
first train the computer by speaking several repetitions of the key word or
phrase into the microphone attached to the computer. The computer saves this as
a voice pattern. To use a voice recognition system successfully, an individual should
be able to reproduce the same speech patterns that were used when setting up
the system; that is, the user needs to speak the same way every time. When the
computer receives voice commands as input, it matches them against the stored
voice patterns and executes the keystrokes set up for that command.
Acceleration Techniques
In conjunction with modified and alternative input methods, other adaptations
increase the rate of input from a keyboard or alternative device. Abbreviation
expansion allows the user to input a predefined shorthand version of a word or
phrase that is automatically expanded by the computer into words. Word lists or
word prediction use the initial letter(s) of the words entered and present a dynamic
menu of word choices. The user then selects the whole word, rather than typing
each letter.
Acceleration techniques may be available as separate software programs that run
with an application program or as built-in features of word processing packages
or multi-purpose adaptive software programs. In addition, acceleration features
are included in some programs that modify keyboard operation and in software
programs for alternate input systems.
Electronic Communication Aids
Individuals who have a physical disability that also affects the muscles used
in speaking may benefit from technology that enhances oral communication.
Portable devices providing synthesized speech or written output may aid
communication. They may be accessed in a variety of ways, including
touch-sensitive keyboards, switches and optical pointers. They may be used
standalone or, in some cases, as alternate input to a computer.
Environmental Controls
An environmental control program helps an individual operate lights, a radio or
television, a telephone or most any electrical device. For example, by using an
environmental control device and a switch or voice recognition system, a person
with reduced motor control can turn appliances on and off. In addition, some
environmental control aids also function as input to a computer for purposes
such as word processing.
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