Produced by Fraser Hamilton,
Designed for All, 2006.
Visual impairments
Visual impairments range from low vision (can see something) to complete blindness. A third type of visual impairment is colour blindness.
People who have low vision which cannot be corrected by spectacles alone may use a screen magnification software such as ZoomText or SuperNova. These packages allow users to ‘zoom in’ or magnify the screen contents to a level that suits them. This means though, that the users can only see a proportion of the screen at any one time, and need to ‘drag’ around the page. Some content may be difficult to recognise at high magnification, such as low resolution images. These packages work with a wide range of applications such as Internet Explorer and MS Office applications.
Not all people with low vision use a third party magnifier. Windows has a range of accessibility features built into it allowing users to choose high contrast text and backgrounds or large fonts. Alternative background and text colours make websites easier to read for dyslexics and those with visual impairments. Website design can incorporate these or provide add on Toolbars.
People who are completely blind, or who see very little, use a screen reader. Screen readers essentially convert on screen text to speech, allowing blind people to ‘hear’ the screen contents. But screen readers are not passive ‘reading’ programs – they have a wealth of functionality for interacting with applications, for example filling in forms on a web page, navigating tables, and selecting links. Common screen readers are JAWS and Window Eyes.
People who are colour blind generally have fewer problems than low vision and blind people. Relying on the use of colour to convey meaning is the key thing to avoid.
Physical Impairments
The range of physical impairments is very wide and varied: from temporary impairments as the result of injury or illness, to Repetitive Strain Injuries (RSI), to permanent paralysis or limb loss. As such the range of assistive technologies is equally diverse. A person with mild RSI, for example, may be able to function well by using a trackball or vertical mouse as a pointing device instead of a mouse. More serious conditions may mean that they are completely reliant on the keyboard or an ergonomic keyboard. One-handed keyboards exist for people who are restricted to using one hand. People who cannot use either hand can use switch technology, for example head mounted pointing and input devices. Speech recognition software such as Dragon Naturally Speaking allows users to access applications by giving speech commands.
Cognitive impairments and dyslexia
People with cognitive impairments, dyslexia and literacy problems can become confused by complex page layouts and complex language. In terms of assistive technologies, these individuals often benefit from text-to-speech software such as Readplease and Texthelp. These packages have less functionality than screen readers that visually impaired people use and this is reflected in their price.
Deaf and hard of hearing people
People who are deaf or have a hearing loss will have problems hearing audio material, such as system alerts and audio tracks. Providing visual equivalents of this audio material, for example as transcripts enables access. However, some deaf people may have English as a second language, British Sign Language being their first.Therefore it is important to use plain English when writing for the web and to also provide content in sign language where possible.
Information on a wide range of assistive technologies can be found on the TechDis website, www.techdis.ac.uk.
