The Usability of a website can only be improved by feedback from testing with real users.
The goal of usability testing is improving the user experience for disabled users and non disabled users alike.
This is particularly crucial and challenging when the users are disabled.
Disabled Usability Testing not only presents particular challenges, but it acquires particular urgency because of the legal obligations imposed on the UK website owner by legislation, chiefly the Disability Discrimination Acts.
Although it is clearly advantageous to do so, there is no legal obligation on a site to meet usability standards for the non-disabled user. But for the disabled user there are Web Accessibility Guidelines to be met, with Public Bodies required to achieve higher grades.
With the disabled user the situation is further complicated for the tester by the fact that his interaction with the site may be mediated by additional Assistive Technology. This can be either externally in the form of non-standard hardware or software (eg a ScreenReader), or via extra facilities built into the website such as options or switches. Examples would be options to increase contrast, or text sizes, or add voice commentary or sign language to media presentations.
Thus the levels of usability achieved depend not only on the factors affecting the regular user, but also on the effectiveness of these accessibility-enhancing tools, and how well they interoperate with the site.
So Disabled Usability Testing cannot avoid entanglement with the testing of the various accessibility-enhancing tools and features.
Further, the WCAG Guidelines which the legislation enforces are not framed in terms merely of a list of techniques to be deployed, but in terms of the quality of the resulting user experience. Which implicitly involves usability in the meeting of the criteria. Indeed the WCAG document itself stresses the need for a Disabled Usability Testing regime as the final step to verification.
The planning and carrying out of the necessary tests must recognise and understand the assistive technologies to be deployed, which may be different for each user, and also understand the particular needs of these very special users.
The disabled population is also more diverse in its needs than the ordinary users, and so it may well be that a larger population of subjects is required if the results are to be sufficiently representative. Whereas three or four subjects might give useful results in ordinary testing, twice that number may be needed where the disabled are involved.
Whatever the extra challenges may be in Usability Testing for the Disabled, every significant UK website will sooner or later have to face the necessity. Not only does the law require it, but in equity the widespread disadvantages currently being suffered by the disabled population need to be brought to an end.
The web is no longer a minority interest. It is fast becoming an indispensable part of modern living, from which no minority can afford to be unfairly excluded.
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