Understanding Disabilities
Many people are born with a disability, while many others find that diminishing
physical or mental abilities occur naturally over time, or as the result
of accidents or diseases. Sometimes these changes can be temporary, sometimes
permanent. Basic life activities include taking care of oneself,
walking, seeing, hearing, speaking, learning, working, performing manual
tasks, participating in community events and activities, and breathing.
Types of Impairments
The following disabilities can make using computers challenging.
Visual impairments
From low vision to blindness, the range of visual limitations is broad.
Symptoms of low vision include dimness, haziness, extreme far-sightedness
or near-sightedness, color blindness, and tunnel vision, among others.
People with these disabilities are concerned with being able to see text
or images on a computer screen and being able to perform tasks that require
eye-hand coordination, such as moving a computer mouse. Text size and color
can make a big difference in legibility for people who have low vision.
Mobility impairments
Mobility impairments can be caused by arthritis, stroke, cerebral palsy,
Parkinson's disease, multiple sclerosis, and loss of limbs or digits, among
others. Poor muscle control or weaknesses can make using standard keyboards
and mouse devices difficult. For instance, some people are unable to type
two keys simultaneously, while others tend to hit multiple keys or to bounce
keys when pressing or releasing them. People who are able to use only one
hand likewise have difficulties with some keyboard and mouse tasks.
Hearing impairments
People with hearing impairments may be able to hear some sound, but may
not be able to distinguish words. Other people may not be able to hear
sound at all. Not being able to hear computer prompts, like beeps and spoken
messages, can be problematic for these individuals. Cognitive and language
impairments Cognitive and language impairments range from dyslexia to difficulties
remembering, solving problems, or perceiving sensory information to problems
comprehending and using language. For people with these impairments, things
like complex or inconsistent displays or word choice can make using computers
more difficult.
Seizure disorders
Specific patterns of light or sound can trigger epileptic seizures in some
susceptible individuals.
Age-Related Impairments
The most common problem people face as they age is the natural deterioration
of eyesight. By age 65, most people have lost at least some of their ability
to focus, resolve images, distinguish colors and adapt to changes in light.
As part of the natural aging process and longevity, the need for contrast
increases because of discoloration in the eye fluids and lens. Most people
have a loss in color perception that accompanies their dimmed vision. With
longevity, people often experience other degenerative effects as well.
Varying degrees of hearing loss are common, as is difficulty with small
motor coordination, often due to arthritis or stiffening of the joints.
The page on <Assistive Technologies> provides information on the
types of assistive technologies used by people with the above disabilities
