The World Wide Web was conceived in a scientific environment to be used by scientists. The original form of the HyperText Markup Language (HTML), the language used to build web pages, was structured around headings, paragraphs and other structures that define the information content of a textual document.
Presentation was a secondary concern.
As the Internet grew and people other than scientists began to access the web, new professional figures, in charge of developing web pages, appeared. The focus was no more on content, but on presentation (see Figure 1): web pages started to be more appealing and rich of graphics.
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Figure 1 – Focus on content and focus on presentation compared
Techniques used included:
• proprietary browser-specific HTML extensions for adding formatting properties;
• using images with fancy fonts for rendering text to replace plain text on the page;
• using images to create graphical elements for presentation, such as fancy borders around the page;
• using data tables for page layout structures, often with blank images to control the white space;
• using plugins or scripting to produce additional effects not provided by HTML.
This approach is characterised by several and severe drawbacks. For what regards web usability, it caused web sites to be not accessible, that means difficult or impossible to be visited by people with accessibility limitations.
Quoting World Wide Web Consortium (W3C), the authority responsible for establishing standards for the web, "web accessibility means access to the
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Web by everyone, regardless of disability". In the following pages we will discuss what is web accessibility, why is web accessibility so important and what is possible to do to make web experience accessible.
Before going on, we stress here that accessibility issues are strictly part of usability research, as they deal with effectiveness, efficiency and satisfaction of specified users while achieve specified goals, that was the definition of usability we have adopted. Hence, a web site that is not accessible cannot be usable for a wide range of population as well.
Web accessibility has become an important issue since the use of the web has spread rapidly into all areas of society and therefore there are millions of people with different kinds of disabilities that have access to the web.
Unfortunately, web sites often provide technological or interface barriers that inhibit the access to these people. Among the various kinds of disabilities that can affect the access to the web, we have:
• hearing disabilities, like deaf, hard-to-hearing or hearing-impaired persons;
• visual disabilities, like blind, colour-blind or visually-impaired persons;
• mobility disabilities, like physical disabled or motor skill impaired persons;
• learning disabilities, like dyslexic persons.
It has been estimated that between 15% and 30% of world population, and almost 10% of internet users, has some kind of disability (Waddell et al., 2003).
We should also consider that the average age of population in many countries is increasing and that the aging process sometimes impairs person’s abilities.
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As the web is becoming a key resource for information, commerce, entertainment, distance learning, job searching, government services and as it is often displacing traditional sources of information, it becomes more important that everyone could access to information.
In fact, web accessibility means to provide and equivalent and effective access to communication sources to everyone, without altering the sources or without imposing hardship to the users.
We have to stress that making web experience accessible implies:
• accessible web sites and web applications, that people with disabilities can perceive, understand, navigate, and interact with;
• accessible web browsers and web applications in general (as rich media players), that can be used effectively by people with disabilities, and that work well with assistive technologies that some people with disabilities uses to access the Web;
• accessible web authoring tools, which support production of accessible Web content and web sites, and that can be used effectively by people with disabilities.
It should be considered that each user has different preferences and habits, as well as disabled persons. It is then important to allow the user controlling the display of the information, not imposing the "look and feel"
of a web site to the user.
To achieve these goals a designer should:
• Design for different browsers: there are many widely spread browsers and not all support the same commands. An accessible web site should be at least visible by every web browser.
• Follow standards: if a designer follows the standard of the language that she is using, it is more probable that the web site will be visible on different browsers and platforms.
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2.1.1 Examples of Web Accessibility
As stated before, the main categories of disabilities that affect persons are four. Each one affects in a different way the access to web sites.
Hearing-impaired persons have difficulties in hearing sounds, hence every audio sound should be captioned or provided of a text equivalent description.
Visually impaired users may have difficulties in seeing images or in reading small text. It is then important to use relative font size (so that the user could change the font dimension according to her needs), to avoid small text, poor colour contrast and excessive graphical images. It should always be considered to not rely on a single one communication channel (e.g., sounds, images or colours) to convey information, in particular when information is relevant or critical. When communicating something with images, it is important to always provide an alternative description, so that even disabled users could understand the meaning of the message. In HTML, there is a way to provide an alternative description for images that will be shown in standard browsers as a tool tip when passing the mouse over the image, while a screen reader tool (usually used by blind persons) can read the alternative description.
Persons with mobility disabilities often use specialized hardware for input, so web site should be designed to be accessible not only with the mouse but also with the keyboard or similar devices.
Cognitively impaired users have often problems in reading web pages, so they benefit from well structured and from clearly written web pages.
2.1.2 Web Usability and Web Accessibilit y
The main difference between web usability and web accessibility is that usability problems affect all users equally, independently from their abilities or disabilities, while accessibility problems affect mostly persons with disabilities. This means that if there are accessibility problems a
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person with disabilities is disadvantaged with respect to a person without a disability.
Accessibility can then be considered as a sub sample of usability, since both affect the access to web sites.
2.1.3 Design for All
Accessible web design contributes to better design for other users.
It is not as strange as it seems. Attention to disability usually implies (but does not limit to) attention to ergonomic design, which can advantage most users. In fact, accessibility contributes to maximize the ability of all users to access information, services, and resources.
The practice of designing accessible interface has been defined as Universal Design (Design for All)
"Universal design is the process of creating products (devices, environments, systems, and processes) which are usable by people with the widest possible range of abilities, operating within the widest possible range of situations (environments, conditions, and
circumstances), as is commercially practical."
(Vanderheiden, 2000)
Designing an universal web site using existing standards and web technologies can produce positive externalities for all users:
• Adopting multimodal interfaces (interfaces that are accessible through different sensorial channels, as visual, auditory, tactile ones) provides benefits for users with mobile devices. In fact, mobile devices are characterized by small displays, low bandwidth, noisy environment and a multimodal interface can improve the interaction. Moreover there are situations in which only the use of multimodal interfaces allows the interaction with the devices, such
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as in-vehicle systems, that allow the user interacting with them while driving.
• Providing redundant text/audio/video equivalents allows supporting different learning styles, low literacy levels, and second-language access.
• Adopting stylesheet technology allows reducing the dimension of transferred web page, increasing the download speed and provides better performance and an higher possibility of personalization.
• Providing an alternative caption for audio sounds allows a better indexing of the content of the web page (useful especially for search engines) and a faster searching of the content.
Nielsen (2001) suggests that disabled users are simply persons who "have jobs to perform and goals to accomplish" while accessing a web site. For this reason a web site should not only be technically accessible to everyone but should also allow everyone accessing its content and should support the execution of tasks.
The Nielsen group recently (2001) performed an usability test on 19 web sites, with 84 disabled users who were blind or had visual or motor impairments.
They asked them to perform several tasks, such as buying a CD, or retrieving information about bus time scheduling, or searching for the best mutual fund. The test was also administrated to a control group of 20 users without disabilities.
The results of the test were that the success rate in performing the test for the control group was three times better than the success rate for the users with disabilities.
Achieving web accessibility should then be considered as a way to provide equal opportunities and to avoid discriminations.
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2.1.4 Guidelines for Accessibility
Recently W3C published several guidelines about web accessibility that play a critical role in making the web accessible, by explaining:
• how to create accessible web sites (Web Content Accessibility Guidelines 1.0 - WCAG);
• how to design software that supports production of accessible web sites (Authoring Tool Accessibility Guidelines 1.0 - ATAG 1.0);
• how to design accessible browsers and authoring tools (User Agent Accessibility Guidelines 1.0 - UAAG 1.0).
The Web Content Accessibility Guidelines 1.0 were developed in 1999 by the Web Content Accessibility Guidelines Working Group inside W3C.
They focus on how to make accessible web sites providing general guidelines. They propose three priority levels of normative checkpoints and provide several supporting resources.
The Authoring Tool Accessibility Guidelines 1.0 were developed in 2000 by the Authoring Tool Accessibility Guidelines Working Group. They focus mostly on the requirements for authoring tools for the web (e.g., programming or image editors, conversion tools) to generate an accessible code. Moreover, they suggest how to realize accessible authoring software.
The User Agent Accessibility Guidelines 1.0 (UAAG 1.0) were developed in 2000 by the User Agent Accessibility Guidelines Working Group. They focus on the realization of accessible applications for accessing web sites and their content, like multimedia players and browsers. Actually, a new working group inside W3C (Evaluation and Repair Tools Working Group) is developing some Techniques for Accessibility Evaluation and Repair. In particular, this group maintains a reference list of tools to evaluate and repair accessibility.
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2.1.5 Accessible Web Sites
The main suggestion of these guidelines is to realize pages that transform gracefully and that can be adapted to different devices.
Accessible web pages should:
• Provide equivalent alternatives to auditory and visual content, which is providing always an alternative textual description, which can be rendered in way accessible to almost every user.
• Do not rely on colour alone, but ensure that the content is understandable even if the page is seen without colours.
• Use markup and stylesheets properly, keeping the style separated from the content.
• Clarify natural language usage, that is explicitate which language is used in the document and how the abbreviations have to be expanded, in order to facilitate multilingual access.
• Create tables that transform gracefully, that are using the appropriate markup to communicate to the user agent which is the structure of the table and how to navigate it.
• Ensure that pages featuring new techno logies transform gracefully and can be seen even if the new technologies are not available.
• Ensure user control of time-sensitive content changes, providing a way to stop the moving, blinking, scrolling, or auto-updating of objects and pages.
• Ensure direct accessibility of embedded user interfaces, allowing every user to access to the interface of a specific object (as the interface of a media player used to play a video file) or to have an equivalent accessible interface.
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• Design for device-independence, enabling the activation of page elements through different input devices.
• Use interim solutions, to ensure backward compatibility with older browsers and user agents.
• Use W3C technologies and guidelines, following the standards.
• Provide context and orientation information, to help people understand how the elements of a page are grouped and which is the relationship between them.
• Provide clear navigation mechanisms to ensure that people can easily find what they are looking for.
• Ensure that documents are clear, with a simple and consistent language, layout and graphics.
It is easy to see that many of the accessibility features required by UAAG 1.0 also improve usability for many other individuals.
For instance, keyboard operation of the user agent benefits some users with visual and physical disabilities, but also benefits users who prefer keyboard access (e.g., expert users). UAAG 1.0 requirements are expected to benefit users with slow Internet connections, as well as users who use their computer in a situation where their hands, ears, or eyes may be busy with other activities.