ACCESSIBLE COMPUTER INTERACTION FOR PEOPLE WITH

DISABILITIES

The case of quadriplegics

Paula Kotzé, Mariki Eloff, Ayodele Adesina-Ojo

School of Computing, University of South Africa, Pretoria, South Africa

Jan Eloff

Department of Computer Science, University of Pretoria, Pretoria, South Africa

Keywords: Accessibility to disabled users, Accessibility options and technology, Quadriplegics, User needs

Abstract: Universal design is the design of products and environments so that anyone can use them without adaptation

or specialised design. Life must be simplified by making products, communications and the built

environment more usable for as many people as possible at little or no extra cost. To understand the chal-

lenges that a disabled person has to face when using the computer, we have to know what capabilities such a

person has. Only then will it be possible to apply universal design to computer interfaces. The purpose of

this paper is to highlight the challenges that many people face in their everyday lives and determine to what

extent disabled people, especially people with limited or no use of their hands and arms, interact independ-

ently with computer equipment. The paper specifically looks at quadriplegics, their capabilities, a survey of

how they use computer equipment, as well as special devices available to assist them in this interaction.

1 INTRODUCTION

The World Health Organisation (WHO) defines a

person with a disability (or activity limitation) as a

person of any age who is unable to perform,

independently and without aid, basic human

activities or tasks, due to a health condition or

physical/cognitive/psychological impairment of a

permanent or temporary nature (Sandhu, 2003).

According to the World Bank estimate, 10% of the

world’s population (approximately 600 million

people) suffer from some form of disability (Metts,

2000). The United Nations (UN), on the other hand,

prefers to identify the percentage of disabilities on a

country-to-country basis, as each country uses dif-

ferent screening techniques during surveys or cen-

suses conducted for people with disabilities (UN

Statistics Division, 2003). From the UN disability

report, it can be seen that the First World countries

appear to have a much higher percentage of disabled

persons than do the Third World countries. For

example, Norway (1996) and New Zealand (1996)

record the ratios of 33% and 20% respectively. On

the other hand, Nigeria (1991) and South Africa

(1980) both documented 0.5% of their population as

having certain limitations. This can be attributed to

the fact that many of the Third World countries have

only rough estimates based on infrequent censuses.

‘In a fair society, all individuals would have

equal opportunity to participate in, or benefit from,

the use of computer resources regardless of race,

sex, religion, age, disability, national origin or other

such similar factors’ (ACM Code of Ethics:

http://www.acm.org/constitution/code.html). Using

computers is becoming increasingly important in

everyday life, not only in the work environment, but

also in our homes. Whether for work or leisure, our

interaction with computers should be as comfortable

and productive as possible. As a minimum

requirement, users must be able to view the display,

reach the input devices, etc. This is especially true

for people with disabilities (Shneiderman, 1993). A

number of factors may intervene to restrict or

prevent users with disabilities from achieving this.

Kotzé P., Eloff M., Adesina-Ojo A. and Eloff J. (2004).

ACCESSIBLE COMPUTER INTERACTION FOR PEOPLE WITH DISABILITIES - The case of quadriplegics.

In Proceedings of the Sixth International Conference on Enterprise Information Systems, pages 97-106

DOI: 10.5220/0002635000970106

 SciTePress

User interfaces often reflect the assumptions that

their designers make about the physiological

characteristics of their users. Interaction objects are

designed so that an ‘average’ user can easily

manipulate (select, copy, move, etc.) them by means

of a mouse, tracker-ball, touch-pad, cursor keys, etc.

Unfortunately the concept of an ‘average user’ is a

myth (Kotze, 2000). Some users, for example, have

the physiological ability and capacity to make fine-

grained selections, but others, such as quadriplegics,

do not.

Do we always realise how frustrating it might be

for a person not to be able to switch on a computer,

let alone insert or remove a diskette? People with

physical limitations may not be able to use these

standard input devices effectively and may benefit

from using special devices or software, for example,

speech recognition software (Loy & Batiste, 2001).

Using the keyboard may require a special device,

allowing the user to press only one key at a time. To

date, disabled people have a tendency to adapt to

technology, and they do not always require or even

demand that technology must be adapted to their

needs (Nordic Guidelines for Computer Accessibil-

ity, 1998). New legislation, based in many cases on

rights entrenched in constitutions and bills of human

rights, is changing this tendency.

Universal design is the design of products and

environments so that anyone can use them without

adaptation or specialised design (Polk, 2000). The

increased pressure for universal access and usability

is a happy by-product of the growth of the Internet.

Services using electronic communication and the

Internet, for example e-commerce, e-learning,

healthcare informatics, international and national

travel, financial systems, mobile communication,

etc., are expanding rapidly and users are becoming

dependent on them. Critics of information

technology abound, but they often focus on the

digital divide of an information-poor minority, with

far less emphasis on the physically and cognitively

challenged (Shneiderman, 2002). To understand the

challenges that a disabled person has to face when

using the computer, we have to know what capabili-

ties such a person has. Only then will it be possible

to apply universal design to computer interfaces.

The purpose of this paper is to investigate and

report on the requirements, status and available

technology to assist quadriplegics in their interaction

with computing devices. Section 2 gives a brief

overview of capability levels of quadriplegics.

Section 3 addresses quadriplegic human-computer

interaction and assistive technology aimed at quad-

riplegics. It gives the results of a survey as to how

people with limited or no hand or finger movement

interact with computers, followed by suggestions on

possible improvements. Section 4 constitutes a

conclusion to these considerations.

2 CAPABILITIES OF

QUADRIPLEGICS

Human limitations related to computer interaction

can be grouped into five categories (Microsoft

Accessibility, 2003; Vanderheiden, 1994):

1. Resource limitations refer to the inability of

people to have access to education and infra-

structure that would better their quality of life.

2. Learning limitations describe the lack of

processing abilities amongst certain people,

which interferes with their learning process.

Such persons typically suffer from dyslexia and

attention deficit disorders, amongst other

limitations, and may require individualised

course presentations.

3. Hearing limitations mean that people may

experience varying degrees of auditory loss,

ranging from slight hearing loss to deafness.

4. Visual limitations include low vision, colour

blindness and blindness. People with these im-

pairments have to rely heavily on other senses

such as touch and sound.

5. Mobility limitations affect people stricken by

certain illnesses or affected by accidents that

deny them the full use of their limbs, who

therefore have difficulty in holding and reaching

for objects or moving around.

This paper will focus only on factors and issues

that are directly related to mobility impairments in

general, and in particular, those factors that are more

likely to affect the use of hands and upper body

parts, with special reference to quadriplegia. Quad-

riplegia, or paralysis from the neck down, can have

many causes. After an introduction to the anatomy

of the spinal cord in Section 2.1, some of the

possible causes of paralysis from the neck down are

briefly mentioned in Section 2.2.

2.1 Anatomy

The central nervous system (CNS) consists of the

brain, spinal cord and nerves. It is in charge of most

functions of the body and mind, which include vol-

untary movements like walking, as well as invol-

untary movements like blinking. The brain interprets

messages from the sensory organs such as the eyes,

nose, skin and tongue, muscles as well as internal

organs. The spinal cord (SC) acts as the information

highway between the body and the brain, and it is

divided into 5 main sections, made up of 33

ICEIS 2004 - HUMAN-COMPUTER INTERACTION

vertebrae that are separated by spongy disks. Each

main section consists of subsections that are mapped

to different parts of the body (with some degree of

overlapping occurring). The first eight segments of

the spinal column at the top of the spine are called

‘cervical vertebrae’ and are named C1 to C8. The

next 12 vertebrae of the upper back are the thoracic

vertebrae, named T1 to T12. T1 lies just below the

eighth cervical vertebra (C8) and T12 lies just above

the first lumbar vertebra (L1). There are five lumbar

vertebrae, L1 to L5, followed by three sacral

vertebrae and the coccygeal (CRPF, 2003; Mosby's

Medical Encyclopaedia, 1997).

Figure 1 depicts this mapping. Although a simi-

lar organization exists for the SC mapping to inter-

nal organs (for hormone release, etc.), it is not dis-

cussed here. Any injury to the cervical vertebrae

will affect the shoulders, arms and/or hands. The

lower the injury, the more functionality the person

will have. A C6/C7 injury may leave a person with

full use of his shoulders and arms, but no movement

of his fingers. A person with all four limbs affected

is called a quadriplegic (or a tetraplegic). A person

with an injury to the thoracic vertebrae will be

affected from the chest down and is termed a

paraplegic. Paraplegics usually have full use of their

arms and hands, and can use the computer in the

same way as any other able-bodied person. Diplegia

is the bilateral paralysis of similar parts of the body.

The research reported upon in this paper focuses on

how people with less than full use of their upper

limbs interact with the computer and what needs to

be done to improve their interaction.

2.2 Diseases and Injury

2.2.1 Spinal Cord Injuries

Spinal cord injuries (SCI) are the result of traumatic

or non-traumatic causes, leading to disruption in the

exchange of information between the brain and the

body, resulting in paralysis (CRPF, 2003). The

trauma can result in severed nerves, pressure on and

bruising of the spinal cord. Paralysis causes loss of

sensation and control over the voluntary movement

and muscles of the body. With SCI, damage to the

spinal cord will only affect areas below the point of

injury. Long-term disability depends on the severity

of the injury, in which nerve fibres are damaged, and

the part of the SC that is injured (National Institute

of Neurological Disorders and Strokes, NINDS,

2003). Traumatic injury occurs most often in young

adult men, and non-traumatic injury is more

common in individuals over 50 years of age. Spinal

cord tumours, spondylosis and vertebral disk

degeneration are common non-traumatic causes of

spinal cord injury (Mosby’s Medical Encyclopedia,

1997). Annually, about 55 million people suffer

from SCI, with about 35 million surviving the acute

injury. Worldwide there are an estimated 500

million to 900 million survivors of SCI. In South

Africa, the leading causes of SCI are vehicle and

sporting accidents, as well as gunshot-related

(violent) injuries (QASA, 2003). There are an esti-

mated 64 000 people in South Africa who are in

wheelchairs (Marais, 2001). More than half of the

individuals are quadriplegic, and the remainder

paraplegic.

2.2.2 Multiple Sclerosis

The nerves in the CNS permit smooth and coordi-

nated movement with little conscious effort. A fatty

tissue, called myelin, surrounds and protects the

nerve fibres of the CNS. Myelin is also responsible

for conduction of electric pulses produced by the

nerve fibres. Multiple Sclerosis (MS) occurs when

demyelination (loss of myelin) occurs, resulting in

areas of the CNS hardening and the formation of

scars or lesions, hence the name ‘multiple sclerosis’

meaning ‘many scars’ (MSIF, 2003). The result is

that impulse conduction of the nerves is slowed or

halted. The symptoms of MS include, inter alia,

chronic fatigue, loss of balance and/or muscular

coordination known as ‘ataxia’, numbness of body

parts such as hands or feet hampering the ability to

hold objects or walk properly. Causes of MS are

mostly unknown, although a person’s gene pool may

contribute (but not directly) to the predisposition. A

person’s gender may also play a part, with 2 to 3

more women than men likely to be afflicted by the

disease. The disease also has a bias for young adults

in the 20-40 year age group and rarely affects

children less than 12 years old or elderly people over

55. Finally, the racial group of northern European

people is more likely to suffer from the disease,

although Asian, African or Hispanic race groups are

not immune to it.

2.2.3 Hemiplegia, Hemiparesis and Cerebral

Palsy

Hemiplegia is the total paralysis of the same side of

the body (CHSA, 2003). It differs from hemiparesis,

which is weakness in one side of the body. The

most common reason for this is a disruption of blood

flow to the brain, resulting in part of the brain dying.

When this occurs, the part of the body that is con-

trolled by the damaged part of the brain will be

weakened. Paralysis occurs in the side of the body

opposite to the affected part of the brain, that is, if

the left side of the brain is affected by insufficient

ACCESSIBLE COMPUTER INTERACTION FOR PEOPLE WITH DISABILITIES: THE CASE OF QUADRIPLEGICS

blood flow, the right side of the body will be para-

lysed, and vice versa. Common causes or

contributing factors of hemiplegia are infections

such as meningitis, brain abscesses, diabetes, high

levels of cholesterol, penetrating and non-

penetrating head trauma, and congenital injuries.

Symptoms of hemiplegia other than paralysis

include loss of sensation in body parts, imbalance

weakness, tremors and unsteadiness. When

paralysis is diagnosed in children, the condition is

called ‘cerebral palsy’. Juvenile paralysis may

produce hemiplegia, paraplegia, quadriplegia or

diplegia (CHSA, 2003).

2.2.4 Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS), or Lou

Gehrig’s disease, is a disorder of the parts of the

CNS that control the voluntary muscles in charge of

voluntary movements (ALSA, 2003). The disease

targets the upper and lower motor neurons. Upper

motor neurons send chemical messages to the lower

motor neurons, which in turn send the messages to

muscles in the limbs, trunk, head and respiratory

system. Malfunctioning neurons cause muscles to

become weakened, severely affecting mobility. ALS

is a progressive disease with continued loss of

function, often resulting in death in as little as 5

years after the onset of symptoms. Very rarely do

people with this disease survive for longer than 10

years after onset. The symptoms usually begin in

one arm or leg, spreading to the other until the entire

body is totally ravaged by the disease, resulting in

complete paralysis. This disease affects adults more

than teenagers, even though its occurrence in young

people cannot be excluded.

2.2.5 Muscular Dystrophy

Muscular Dystrophy (MD) is a name given to a

group of diseases that are hereditary and often

manifest as non-rapid progressive wasting of

muscles that control body movement (MDAC,

2003). This causes a characteristic, selective pattern

of weaknesses and thus targets different parts of the

body with different people. Muscular dystrophy is

not contagious. The clinical onset may begin at any

time in childhood or adulthood. For example,

Duchenne MD is often detected in children between

the ages of 2–6 years and affects only boys. Distal

MD, on the other hand, develops in adults in the 40–

60 year age group. In cases where the mother is the

carrier, her sons are more likely to be infected and

her daughters will only be carriers of the disease.

Although this disease has no cure, therapy can help

to maintain a certain level of independence with a

normal life span.

2.2.6 Repetitive Stress Injuries

The term ‘repetitive stress injury’ (RSI), or

‘repetitive strain’, refers to a group of conditions

caused by placing too much stress on a joint.

Repetitive stress injury happens when the same

action is performed repeatedly (RSIA, 2003). When

an action that is stressful to a joint is repeated

frequently, the area does not have time to recover

and it becomes irritated. This can cause the area to

become painful and swollen. One of the most com-

mon types of repetitive stress injury is carpal tunnel

syndrome. The median nerve is the most sensitive

nerve that travels down the arm to the hand to the

thumb, index, middle and half of the ‘ring’ fingers.

It passes through a narrow path (a tunnel) at the

wrist. The ailment ‘carpal tunnel syndrome’ occurs

when bones and ligaments in the wrist joint causing

tingling sensations or numbness, compress the

median. If left untreated, it can cause complete loss

of feeling in most of the fingers as nerves become

damaged. Carpal tunnel syndrome can affect any-

one, but mostly occurs in women aged 40–45 years

and among people involved in heavy labour.

2.2.7 Parkinson’s Disease

Parkinson's disease is a progressive disorder of the

CNS (The Parkinson’s Web, 2003). It causes

muscle stiffness and rigidity, tremors and slowness

of movement. The main cause of Parkinson’s

disease is unknown, although there are unverified

claims that it is linked to inherited genes and

environmental triggers. The disease begins when

there is a shortage of a brain-signalling chemical

called dopamine. Symptoms are initially subtle but

worsen within 3–5 years as the disease progresses,

until eventually no medication can control any

advancement. The disorder is not contagious and

very seldom affects people younger than 30 years

old, but likelihood drastically increases with age,

especially after fifty.

2.2.8 Arthritis

Arthritis is the inflammation of joints causing

swelling, stiffness and difficulty in the movement of

fingers, wrists, knees and hips, amongst other body

parts (AA, 2003). There are two main categories,

namely osteoarthritis (OA) and rheumatoid arthritis

(RA). Causes of both forms of arthritis are largely

unknown, although OA is attributed to the release of

too many enzymes that cause the joint cartilage to

break down. Eventually, the cartilage wears out

completely, the joints start to rub together, and the

bone loses its shape and juts out, forming lumps.

RA, on the other hand, may be triggered by

ICEIS 2004 - HUMAN-COMPUTER INTERACTION

100

inflammation of the joint lining instigated when

white blood cells migrate to the capsule that contains

lubrication fluid for joints. OA affects more women

than men over the age of 45 and especially after

menopause, while RA affects more men than women

at an age younger than 45. Juvenile cases of arthritis

have also been identified, with children as young as

a few months being stricken by the ailment (CHSA,

2003).

3 QUADRIPLEGIC HUMAN-

COMPUTER INTERACTION

As mentioned in the introduction, in this paper we

will specifically focus on quadriplegics. Quadri-

plegics (quads) are in wheelchairs. The first com-

puter interaction obstacle they need to overcome is

the physical position of the CPU, screen and key-

board. Does the wheelchair fit comfortably under

the desk or table? Can the user reach and use the

keyboard with ease? Is it possible to position the

CPU box in such a way that the user can switch the

computer on/off? If it is too high or to low, it might

be difficult to reach. The same applies to using the

diskette drive and CD ROM.

A quadriplegic may not have full functional use

of his/her hands and may use the keyboard with a

splint or special strap on one hand that holds a stick

to press the keys. The one end of the stick is

generally covered with a piece of sponge or rubber

to improve typing, otherwise the stick might slip off

the desired key. As can be expected, the typing

speed may be quite slow. Some users may use a

stick in their mouths on the keyboard. Holding the

‘shift’ or ‘control’ key down and then pressing

another key with a stick in one hand is just short of

impossible. Using the mouse may also be an uphill

battle for some users – to be able to move the mouse

to the desired position and then ‘click’ using both

hands with limited finger function might not be very

easy, let alone comfortable. Different pointing

devices do give the user a choice. Notebooks come

with built-in pointing devices – a touch-and-drag

type of mouse, track ball or even a little peg in the

keyboard. An ‘external’ mouse can be connected to

a laptop, if desired.

3.1 Survey on how quadriplegics

interact with computers

Before any suggestions on improving computer

interaction for disabled people can be made, we need

to determine exactly how disabled people currently

interact with computers. A survey was conducted

amongst quads with limited functionality in their

hands, wrists or arms. The aim of the survey was to

find out what they can do when using the computer

and how they do it. A total of 20 quads were inter-

viewed, with disability causes ranging from spinal

cord injuries, polio, cerebral palsy to muscle dystro-

phy. The following summarises the major findings:

– 82% suffered from spinal cord injuries, 6% from

muscular dystrophy, 6% from cerebral palsy and

6 % were disabled due to childhood polio.

– 25% could not switch the computer on or off,

while 31% could not use the diskette drive

effectively, and 38% of the users could not use

the CD-ROM. Seventeen per cent into all three

categories.

– The keyboard was used by operating a stick in a

splint by 41% of the users (all with spinal cord

injuries), 44% by one hand or fingers from one

hand and 19% with both hands, or fingers from

both hands.

– 88% of the users used a mouse. Twenty-six per

cent of these used both hands, while the

remainder used the mouse with only one hand.

Sixty-six per cent of these used an ordinary

mouse, while the others used a trackball type

mouse or a touchpad.

– Only 56% knew about sticky keys, while only

25% used them.

– 63% of the respondents used a computer before

their disability.

– 40% of the respondents were male and 60%

female, ranging in age from late teens to mid-

fifties, with all having completed high school

and 81% having a tertiary degree qualification.

Some of the specific problems that were mentioned

include the following:

– It is too difficult to change the volume control on

the speakers – even if they are within reach. The

buttons are too small and too stiff to turn with

limited or no finger movement.

– It would help if the keys were more sensitive to

touch and easy to press – they are sometimes too

stiff. Even a keyboard with the keys wider apart

may make a difference.

– An easier way to switch the computer on or off –

what about using the keyboard?

– Predictive text would also help, provided it func-

tioned correctly.

– Voice recognition is not the answer for all – two

of the seven people who used voice recognition

software were highly frustrated with it and either

stopped using computers or reverted back to the

keyboard and mouse.

– Few users who used the keyboard knew about

sticky keys or the other accessibility options in

Windows.

ACCESSIBLE COMPUTER INTERACTION FOR PEOPLE WITH DISABILITIES: THE CASE OF QUADRIPLEGICS

101

One major item of feedback was the fact that all

the people interviewed adapted to the computer

technology, and did not require the technology to

adapt or be changed to suit their needs. The reason

for this can be twofold. First is the lack of

knowledge that other possibilities may exist – they

use what is available without searching for other

solutions or even requesting, let alone demanding,

that the technology be changed to suit their needs.

When the users were asked what they would like to

have changed, there were few requests. Secondly,

there seems to be a lack of customer support,

especially regarding the voice recognition software.

3.2 Suggestions on possible

improvements

The flexibility of computer software makes it possi-

ble for designers to provide special services for users

with disabilities. Designers can benefit by planning

early on to accommodate users with disabilities and

work more closely with computer users with special

needs in order to design what will suit them (Kotze,

2000). It is, however, pertinent that new technology

options be communicated to users with special

needs.

Assistive technologies or electronic curb cuts

(from the term curb-cut in city sidewalks to facilitate

wheelchair mobility) are technologies that are

needed to enhance disabled persons’ independence,

self-esteem and over-all quality of life (UN, 2003).

Assistive technologies developed specifically for

computer technology are required to allow users to

have seamless access to computer technology and,

more importantly, to permit full customisation. Full

customisability of computer assistive technologies is

required as disabilities grouped even within the same

category may differ by varying degrees, as was

indicated by the results of our survey. Although

assistive technologies were initially developed for

people with various limitations, many of the

developments, such as remote controls, have

inevitably benefited everyone (TIA, 1996). This

should therefore be an incentive for further research

into the development of newer and more

comfortable equipment. Apart from humanitarian

reasons, other incentives for producing accessible

products include compliance with standards and

regulations laid down by organisations such as the

UN and the WHO. Economic factors also buttress

the argument for assistive technologies. As stated

before, according to the World Bank, 10% of the

world’s population suffers from some form of

disability, therefore increasing the potential

customer base (which is big already). Assistive

technology also means that there is no loss of

expertise or revenues for the organisations with an

aging population, and employees with temporarily or

permanently acquired disabilities would have a

trouble-free reintegration into the workplace after

recuperation and rehabilitation (NGCA, 1998). Our

survey indicated that 81% of the respondents had a

degree qualification, while 63% of these had a

postgraduate qualification, and were therefore

potentially highly valuable to the workforce.

Standard hardware and software technologies

provided by information technology vendors often

provide inexpensive access features that can be used

by persons with less severe cases of motor disability.

Therefore, before discussing specific hardware and

software developed for quadriplegia, an overview is

given of access features provided by status quo

technologies.

3.2.1 Status Quo Technologies

The Dvorak keyboard was designed to provide an

alternative keyboard arrangement to the standard

QWERTY keyboard. The commonly used letters

(namely the vowels ‘AOEUI’ and most common

consonants ‘DHTNS’) of the English language are

arranged on the ‘home’ row. The rationale behind

this arrangement stems from the fact that, with these

letters being the most commonly used, a keyboard

arrangement to accommodate them greatly decreases

the amount of hand-motion required to type

documents (Grassie, 2001). In the light of this,

some existing operating systems (OS) provide the

ability for one to convert from the standard

QWERTY arrangement to that of the Dvorak. The

software required to reconfigure a keyboard is

sometimes pre-installed in the OS, or may be

downloaded or purchased from the appropriate

organisation. Following the conversion of the key-

board configuration, the key-caps are popped off and

re-arranged to reflect the new configuration. As an

alternative, some organisations such as Microsoft®

(Microsoft Accessibility, 2003) provide free

downloadable stickers to be placed over the existing

keyboard layout, thus eliminating the need to change

a keyboard’s layout physically.

Application programs provide keyboard short-

cuts for persons who are able to type on keyboards

but lack the dexterity required to use alternative

input devices such as the mouse. To facilitate menu

activation and other functionalities such as saving a

file, a single key or a combination of keys can be

employed in accomplishing such tasks. As exam-

ples, Microsoft® application programs use CTRL +

SHIFT + < to decrease the font size of characters.

Similarly, with Apple® computers, the keyboard

ICEIS 2004 - HUMAN-COMPUTER INTERACTION

102

combination COMMAND + SHIFT +1 is used to

eject a diskette from its drive. Also available are

mechanisms to change default shortcuts provided by

software by either creating new shortcuts or deleting

some default values that one considers redundant

(Dallabrida, 2002).

To further decrease the discomfort sometimes

associated with using the keyboard, other

complementary access functions are available.

‘Sticky keys’ is a software latch that enables one to

depress a combination of modifier keys in sequence

rather than simultaneously, and have it remain active

until a non-modifier key is pressed. This feature is

extremely useful for mobility-impaired persons,

such as quadriplegics, as keyboard shortcuts can be

used more easily. Slow keys permit users to alter

the length of time taken for keystrokes to be regis-

tered on the screen. This allows accidental key

depression to be cancelled without any adverse

effects. Toggle keys alert the user by sounding a

signal when the caps lock, num lock or scroll lock

key is activated. This ensures that the user is

informed about accidental key depressions. Filter

keys allow brief or repeated keystrokes to be

ignored, or slow down the repeat rate. Finally,

‘mouse keys’ is a program that permits one to

control cursor movements via the keyboard, thereby

allowing persons who lack the deftness required for

mouse manoeuvring to simulate the action. The

keypad numbers on a keyboard become compass

points and numbers such as ‘5’ act as the mouse

button, ‘8’ is used to move the cursor upwards, the

number ‘2’ moves the cursor downwards, etc.

Unfortunately, very few users know about these

features. The ideal would be to communicate this

information to all possible users who would benefit

from using the accessibility options.

3.2.2 Assistive Hardware Technology for

Quads

Although each technology is presented individually,

it is often the case that more than one of these tech-

nologies are used together in order to accomplish

tasks. The hardware technology (and software tech-

nology in the next section) addressed here is specifi-

cally geared towards quads. Several other technolo-

gies aimed at other forms of mobility impairments

and disabilities also exist. In addition, some of the

following technologies are not confined to disabili-

ties involving mobility alone, but are equally appli-

cable to other disabilities such as visual

impairments.

3.2.2.1 Switch/Morse Code Interface

Switches can be controlled by almost any body part

and activated with a press, kick, swipe, head move-

ment, eye blink, and sip and puff devices. It can be

mounted on a wheelchair, for example, allowing

close proximity to the user. The Morse code

interface is perhaps the most popular switch

interface in that users can quickly adapt to using

Morse code and can achieve high entry speeds. See

Figure 2.

3.2.2.2 Head Mouse

A head mouse is a head-mounted wireless optical

tracking system. Users’ head movements are trans-

lated into proportional movements of the mouse

pointer. On-screen items (e.g. icons) are selected

when the cursor is left stationary on the item for a

programmable length of time. See Figure 1.

3.2.2.3 Eye-tracking Systems

An eye-tracking system is an alternative input device

for hands-free text entry and pointing operations.

The main advantage thereof is that it requires no

head-mounted technology. A camera is mounted on

the monitor and focused on the eye, while integrated

software gauges where the user is looking. Clicks

are made either with slow blinks or with hard stares.

The disadvantage of this device is that it requires the

user to hold his /her head steady. See Figure 4.

3.2.2.4 Sip and puff systems

Sip and puff systems are activated by users’ breath.

Puffs generate a click or selection, thereby ‘replac-

ing’ the need for mouse buttons. See Figure 5.

3.2.3 Assistive Software Technology for

Quads

3.2.3.1 Keyboard Filters

Keyboard filters, such as the KeyRep Program

(Nanopac Inc., 2003), are hands-on devices used for

word prediction, abbreviation-expansion,

Figure 1: Head mous

(http://orin.com/access/headmouse/phm.htm)

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103

customizable dictionaries, and decreasing the

number of required keystrokes.

3.2.3.2 On-screen keyboard

On-screen keyboards, such as OnScreen v. 1.75, are

devices where an image of a standard or modified

keyboard is provided on the screen. Keyboard keys

can be activated by practically any of the pointing

devices. For people who can move the mouse cursor

but cannot click, the software can be programmed to

allow key selection after a certain length of time.

See Figure 6.

3.2.3.3 Voice/Speech Recognition Technology

Voice/Speech Recognition Technology, for example

Dragon NaturallySpeaking®, consists of hands-free

devices that users can use to produce text or activate

functions just by speaking (Nanopac Inc., 2003).

They relieve the users of the physical exertion

required by direct hands-on input.

3.2.3.4 Screen Readers

Screen readers, for example JAWS®, are software

programs that verbalize everything on screen (e.g.

graphics, text, punctuation, names and descriptions

of buttons and menus) as speech (Nanopac Inc.,

2003). A program of this sort will transform a GUI

to an audio interface (using an internal speech

synthesizer and sound card), and lessens the effort

required to scan through the output interface

3.2.4 Software Development Guidelines

In order to achieve a truly accessible information

society, many countries, international organisations

and developers are putting forward guidelines to

ensure that products are accessible and compatible.

Development software must also have the capability

of programming built-in accessibility features.

These features must be able to accommodate visual,

auditory or motor disabilities. If guidelines are

adhered to during the development process, costs of

modifying completed products will not be an added

liability (TIA, 1996).

The following is a list of requirements that

should, at a minimum, be demanded by customers

and be taken into consideration by designers, devel-

opers and vendors of software products for quadri-

plegics and other users with mobility disabilities

(IBM Accessibility Center, 2003; Nordic Guidelines

for Computer Accessibility, 1998; TIA, 1996):

– Keyboard navigation: Provide mnemonics

(accelerators) on graphical user interface com-

ponents and functions; set tab order to standard

top-2-bottom left-2-right (T2B, L2R) navigation;

allow user navigation between and within

menus, using the keyboard; equip all compo-

nents with accessibility labels so that screen

readers can verbalise them; and set the focus on

the primary object that the user must operate.

Screen readers also require the focus to be set in

order to know which component to verbalise.

– User interfaces must be customisable.

– Provide redundant information for all objects:

sound, text and graphics.

– Avoid interference with preset accessibility

features such as sticky keys by not using

keyboard sequences reserved for such features.

– Allow a time delay when requesting input from

the user, as people with mobility disabilities may

require more time for movement.

– Provide for compatibility with assistive technol-

ogy. Provide accurate documentation for all

accessibility features in a number of accessible

formats, for example, having the documentation

available in both an HTML format (which is

more compatible with screen readers) and PDF

format, and test completed software with a wide

range of assistive technologies.

3.2.5 Hardware Development Guidelines

The following is a list of requirements that

should, at a minimum, be demanded by customers

and be taken into consideration by designers, devel-

opers and vendors of hardware products for quadri-

plegics and other users with mobility disabilities

(IBM Accessibility Center, 2003; Nordic Guidelines

for Computer Accessibility. 1998; TIA, 1996):

– Users should not have to grasp, simultaneously

twist and turn, use twisting motions or press sev-

eral controls simultaneously.

– Button sizes for pushbutton controls must be

between 1.25 and 2.5cm for finger activation,

and 1.5 and 7.5cm for palm activation.

– Separation distances for pushbutton controls

must be 1.25cm for finger activation and 5.0cm

for palm activation.

– Force required to activate pushbutton controls

must not exceed 270 to 540g for finger acti-

vation, or 270 to 2160g for palm activation.

(Other controls have similar minimum/maximum

force, size or separation requirements).

– Texture of controls must be matte and non-slip,

with redundant clues e.g. colour-coded, raised,

with grooves, serrations or scallops.

– Components must not be made of materials that

could trigger allergic reactions.

– Switch guards must be provided for critical

switches as well as time-delays before activation.

– Keyboard keys and mouse buttons must be stiff

enough to support resting fingers without being

activated.

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– Ejected media such as diskettes and CDs must

protrude at least 1.25cm.

– Provide load and unload ability for media via

keyboard keys.

– Ensure that standard hardware and software

interface properly with specialised assistive

technologies.

– Security systems must provide alternative means

of authorisation other than biometrics.

– Test hardware widely on people with varying

degrees of limitations.

– Procurement guidelines: Developers must be

required to declare which accessibility guidelines

were adopted as the basis for their products.

‘Request for proposals’ and ‘request for

quotations’ must explicitly indicate the

accessibility features that vendors must include

in their product in order to be allowed to tender

for contracts.

4 CONCLUSION

This paper reported on an investigation into how

quadriplegics use computer hardware and software,

as well as technology to support this group of users.

Some of the problems that they face were

highlighted. Our study emphasised the fact that in

order to successfully develop usable hardware and

software for disabled persons, such as quadriplegics,

they must be directly involved in the developments

and testing of such technology. It also emphasised

that if technology is adapted to suit disabled users,

everybody can benefit, even ordinary able-bodied

users. Some of the technology examples described in

this paper was specifically developed with the

disabled person in mind, but have found uses in

various other application areas. Our paper concluded

by providing guidelines for the development of

computer software and hardware for quadriplegics.

It is the basic human right of disabled persons to be

able to interact effectively and efficiency with com-

puter equipment. If support for such interaction is

not provided, it can be seen as a form of technologi-

cal ‘apartheid’. It is hoped that designers will take

note of the needs of disabled people, and design and

build accessible technology to help the disabled to

maximize their interaction with computers. The

concept of universal design should be emphasised.

Technology must be adapted to the needs of the

users, and not vice versa.

The work reported upon in this article is partly

based on work sponsored by a grant from the

National Research Foundation of South Africa under

Grant Number GUN: 2054025.

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