Types of disability
Understanding accessibility issues when designing websites
Disabilities are numerous and varied and technology is advancing creating new problems and solving others. The problem is not a static one. Guidelines are published by WC3 to assist web designers make due allowance for accessibility. Assistive technology is a piece of equipment or a software product that is used to increase, maintain, or assist the functional capabilities of individuals that have difficulty accessing the internet. There is a significant amount that can be done by the web developer to minimise or remove barriers, if only the effort is put in.
Disabilities explained
The four main categories of disabilities are
- visual
- hearing
- mobility
- cognitive and learning difficulties
Visual
People with visual disabilities are individuals who are blind, have reduced sight capability, or have colour blindness.
People who are blind will be using screen readers and they will be using their keyboard rather than a mouse. The obvious requirements are:
- to have text equivalents for all meaningful visual images
- to provide keyboard based navigation.
But consider some less obvious issues:
Links
- Screen readers can jump from link to link, so "click here" is not very useful with the context in the link.
- Links that are part of javascript effects will confuse as they do not go anywhere.
Page structure
- Traditionally tables have been used extensively to place content, it is the easy way to create complex structures for pages and it is the traditional way of placing complex graphics. However interpreting the code -as with a screen reader - can be very difficult. Items in table cells which appear to be next to each other when viewed visually, may actually be separated by other cells within the code. Items may be read out by the screen reader in a very disjointed format. A considerable number of table cells may need to be navigated to get to relevant pieces of content giving the blind user a very frustrating and difficult experience of the web site.
- Where tables are used they should be clearly labelled with column and row headings. Care needs to be taken with merged cells. Complex tables should have good descriptions.
Colour
- People who are colour blind or who have low vision may not see content unless there is high contrast between background and foreground colours.
- When information is presented by colour alone, a person who is colour blind may miss that information as various colours appear identical to them.
- A user may wish to change the colours of text and backgrounds.
Magnification
- A user with reduced vision may want to control the size of the text themselves - this can be done in most standard browsers provided the website allows this to happen. The design of the website should allow for elements to change size and still be presentable.
- Magnification aids might reformat the location, change the contrast, or distort the size and fonts of the text and objects on the Web page.
- Large areas of space may cause a problem in magnification. The area of space becomes larger so the user has to scroll for longer and may miss valuable information.
Mouseover Effects
- These are not going to work if you don't use a mouse so alternatives are required.
Frames
- These are separate files so they will be visited separately - the whole picture will not be seen. Frames may cause confusion.
Read more on Assistive Technologies
Useful external links on visual issues
Read more on visual
disabilities at www.webaim.org
Experience a simulation
of a screen reader at www.webaim.org
See a simulation of a website as seen with
visual impairments at www.webaim.org
See the effects of colour
blindness at www.vischeck.com
See what
colour blind people see with these java simulations by Hans Brettel
Read an article on effective
colour contrast at www.lighthouse.org
Hearing
People who are deaf or hard of hearing require visual representations of auditory information.
Useful external links on hearing issues
Read more on hearing disabilities
at www.webaim.org
Mobility
People with mobility disabilities have physical impairments that substantially limit movement and fine motor controls. Using a mouse may not be possible, using a keyboard may be possible but only one key press at a time. Voice input assistive technology may be used. Making the Web site accessible will make it more compatible with voice input and control technologies.
Useful external links on mobility issues (each link will open in a new browser window)
Read more on motor disabilities
at www.webaim.org
See an inaccessible website demonstration at
Disability Rights Commission
Cognitive and Learning Disabilities
People with cognitive or learning disabilities, such as dyslexia and short-term memory deficit, need more general solutions, which include providing a consistent design and using simplified language. Graphics may assist their understanding. People with cognitive or learning disabilities can also benefit from both an audio file and a transcript of a video. By simultaneously viewing the text and hearing it read aloud, they can take advantage of both auditory and visual skills to comprehend the material better.
Useful external links on cognitive and learning disabilities
Read more on on cognitive
disabilities at www.webaim.org
Experience Distractability Simulation at
www.webaim.org