March 9, 2001
By Michael G. Paciello
The subject matter in this excerpt centers on people with disabilities. It is much easier to explain what you need to do to make your Web site more accessible when administrators, designers, and engineers understand the user characteristics of the disabled. If you are not a person with a disability—for example, loss of vision, hearing, or mobility—then likely you're not familiar with their needs as Web surfers. In the development of any interface, the first rule of thumb is "know thy user."
The following descriptions of the different groups of people with disabilities are not intended to be complete or exhaustive. For the purposes of this excerpt, I try to identify the communities of people with disabilities who appear to be most affected by the inaccessibility of the Web today. Therefore, in addition to descriptions of the disability, each category also briefly highlights the barriers that people with disabilities must overcome in order to use the Web.
This does not imply that other communities are, in some way, affected less or not affected at all. Remember that the goal is to achieve accessibility to the greatest extent possible for all people with disabilities. By building awareness around the current issues and the most visible areas of inaccessibility, this book helps identify new areas that can be resolved in the near future.
People Who Are Blind or Visually Disabled
Of all the disability communities concerned by the inaccessibility of the Web, people with visual disabilities probably rank first. This is primarily due to the graphical nature of the Web's client-server interface.
Visual disabilities vary in category including low vision, color blindness, and total blindness. The following sections contain a description of each.
The American Academy of Ophthalmology defines low vision as follows:
If ordinary eyeglasses, contact lenses or intraocular lens implants don't give you clear vision, you are said to have low vision. Don't confuse this condition with blindness. People with low vision still have useful vision that can often be improved with visual devices. Whether your visual impairment is mild or severe, low vision generally means that your vision does not meet your needs. Using visual devices to improve your vision usually begins after your ophthalmologist has completed medical or surgical treatment or determined that such treatments will not improve your vision.On the Web and when using computers, many people with low vision use specialized monitors or software that increases the size of text or images large enough for the individual to see. Web sites that use absolute font sizes make it difficult for the low vision user to make this adjustment using his or her computer.
Additionally, some low vision users have difficulty making out certain font styles. Italic text, for example, may be difficult for a low vision user to read without assistive software. (However, in all honesty, italic text is difficult for individuals with good vision to read. This is often due to inadequate screen resolution or poor font quality.)
People who are color blind often have difficulties in distinguishing between combinations and/or pairs of colors.
On his Web site, Andrew Oakley provides in-depth descriptions of the various types of color blindness:
At the back of your eyes you have Cones and Rods. Cones pick up colour. Rods pick up brightness. There are blue cones, red cones and green cones. They pick up different wavelengths of light. Colour blind people have less numbers of particular cones than normal, so they get colours confused. Some people are more colour blind than others.Web accessibility issues for individuals who are color blind often involve color combinations that are not properly coordinated or do not provide high contrast. Images without alternative text are also an inconvenience, particularly when the individual is not able to discern what the image is due to the nature of his or her blindness.
You can learn more about color blindness at the Lighthouse International Web site.
Blindness comes in a variety of degrees. Most people defined as being blind often do have a measure of sight, as limited as it might be. For example, a person whose level of sight is equal to or less than 20/200—even with corrective glasses or lenses—is considered legally blind. A person who is completely sightless is considered to be blind .
Many diseases and conditions contribute to or cause blindness including cataracts, cerebral palsy, diabetes, glaucoma, and multiple sclerosis. Many of these conditions are more prevalent as we age.
Web accessibility for people who are blind is a considerable challenge based on the obvious fact that the Web is a visual interface. Images without associated text, frames, tables, forms, and interactive content are just a few of the problems that perplex these users.
People Who Are Deaf or Hard of Hearing
Up front, it's very important that so-called "able-bodied" people understand some important distinctions regarding those who are typically classified as "people with disabilities." For example, this section purposely differentiates between people who are deaf and people who are hard of hearing . This is a crucial distinction. Generally speaking, the deaf do not consider themselves hard of hearing. Their hearing is not impaired; it simply does not exist.
Quite obviously, then, a person who is hard of hearing is one who has lost a degree of his or her ability to hear. These individuals may need an amplifying device in order to have functional hearing.
It is also important to know that people who are deaf do not consider themselves "disabled" or "functionally limited." They prefer the distinction of being their own culture that includes their own form of communication, which is usually sign language. Deaf World Web is an excellent resource that provides information about the deaf culture and includes a useful American Sign Language dictionary.
The fact that the deaf culture is included in the category of people with disabilities is primarily based on the increasing prevalence of Web multimedia content that includes dialogue and sound but does not include captioning. Additionally, with the growing popularity of speech recognition interfaces, people within the deaf culture who have limited speech capacity (or none at all) run the risk of being shut out of next-generation computing interfaces all together.
People with Speech Disabilities
Individuals who have speech limitations or speech disabilities collectively include a population of people who have weakened speaking ability or a complete loss of their ability to speak.
You may not consider the population of people with limited speaking ability to be that significant. In fact, there are a variety of disabilities and conditions that include limited speech functionality as a secondary aspect of the disability. The publication titled Extend Their Reach notes the following:
Speech limitations, like other disabilities vary greatly in severity and cause. They might result from severe language delay, cerebral palsy, mental retardation, autism, traumatic brain injury, or stroke. Speech problems can also result from several disorders affecting nerves and muscles including ALS, dystonia, Huntington's disease, multiple sclerosis, and muscular dystrophy.Similar to the problems facing people who are deaf and hard of hearing, individuals with speech disabilities are dangerously at risk of being ignored as speech recognition interfaces become the norm.
People with Physical Disabilities and Motor Impairments
For people with physical disabilities or motor impairments, accessibility issues can take on a wide range of challenges. Some people have use of their hands while others do not. Some have the ability to use mouth sticks and head pointers while others rely on infrared devices.
Physical impairments are wide and varied. They include conditions such as muscle weakness, paralysis, joint discomfort, and spinal injuries, or disease processes such as arthritis and muscular dystrophy.
Functional limitations as a result of Repetitive Strain Injury (RSI) have increased dramatically over the years. Ironically, one of the key reasons for this increase is directly related to use of personal computers. This led to a growth in the use of emerging technologies such as speech recognition.
The growing popularity of Web appliances and devices such as WebTV and Web kiosks, if not properly designed and tested, will present numerous challenges for the physically challenged user.
People with Cognitive or Neurological Disabilities
Cognitive and neurological disabilities may seem a little more difficult to address. However, as with outwardly apparent physical disabilities, the improvements made to your Web authoring techniques will serve more than the disabilities community.
Individuals with dyslexia, dyscalculia, and auditory perception difficulties benefit from information being presented in short, discrete units. Easily digestible chunks of data make the important points in your content stand out as well.
conditions can result in users being sensitive to excessive flashing in
animations or blinking that occurs within certain ranges of frequencies.
Seizure disorders have been known to be triggered by such events. Any time
that the eye is distracted from the real content of the page, your meaning
may be lost.
Mike is Founder and Chief Technology Officer of WebABLE, Inc., an accessibility education and consulting firm.
Introducing Web Accessibility
The Web Accessibility Initiative
Users Matter: Meeting Site Visitor Needs