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The digital magazine of InfoVis.net

Accessibility: pending subject
by Juan C. Dürsteler [message nº 10]

Accessibility is the possibility to have access to a resource. Something less usual in our web sites than we think. Not only because they are difficult to access for disabled people, but because the level of usability and the difficulty of designing the content presentation for so different devices like mobile phones, WAP or WebTV decreases our ability to communicate with them effectively. 

According to the Disability Statistics Center about 20% of the American population suffer certain degree of disability. Half of them severely. 30 Million U.S. people have some kind of trouble when using the typical computer input and output devices. The extrapolation to the world population gives some 750 Million people as seriously disabled. Too many people (customers) to be ignored.

The most disturbing sort of disability for InfoVis is visual disability. Blind or subnormal vision people find themselves severely limited when exploring a page full of graphics. In that case, the converters of text to synthesised speech, like IBM Home Page reader, just don't work. This Netscape plug-in is available for different languages, Spanish among them. 

Let's remember that the robots used by the search engines spread on the Net looking for information are intrinsically blind. If we want them to find us our web should be able to be navigated without the need to "see" the graphics.

Those suffering some form of daltonism (colour blindness) can experience serious difficulties in a page where the text and the background colours are those that they confuse. For example, the standard colours for the visited and non-visited links appear the same for deuteranopes. 

On the other hand, many people suffer situational disabilities. These are derived from the inability to relate with the source of information instead from being of physiological or pathological nature. Accessing the web from a mobile phone, a PDA or a fully equiped multimedia PC is not the same

Accessing to a web site optimised for a particular resolution and Browser, converts the users that don't operate under these conditions in situationally disabled people. People that don't know one of the predominant languages of the Net (especially English) or that don't have
updated software suffer a situational disability when they try to access information in Internet.

More and more the information is being transmitted through non PC devices. It's the case of mobile phones or WebTV. There are already devices that allow the translation of digital information to Braille (Braille display) in real time. The currently existing web sites are not optimised to support so different platforms.

How can we improve the accessibility?. There are many resources on the topic. You can find some Spanish speaking resources in the Spanish version of this article.

The W3C consortium has made a series of documents of recommended reading on accessibility within the scope of WAI, the Web Accessibility Initiative. The web of Newcastle University in Australia has also many resources for making web pages more accessible in its web site.

We can also use software that helps to improve the accessibility. As an example you have Bobby  freely distributed by CAST, or the tools of WebMetrics, coming from the always-efficient National Institute of Standards and Technology (NIST).

To ensure that the chosen colours are distinguishable for the different users we have Vischeck, a program that simulates how a user with anomalies in colour vision sees our web pages. Finally, it's advisable to take a look at our web pages through a text-only browser like Lynx in order to be aware of many of the accessibility problems our web site could have.

Most of the techniques to enhance the accessibility of disabled people improve noticeably the overall usability. The proliferation of new situations and devices to access information and the existence of numerous groups of people with physiological or situational disabilities reveals that accessibility is a need for all of us.

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