A bridge to Web Accessibility from the Usability ... - Semantic Scholar

Draft Version USAB 2009, LNCS 5889, pp. 290–300, 2009. Springer-Verlag Berlin Heidelberg 2009

A bridge to Web Accessibility from the Usability Heuristics Lourdes Moreno, Paloma Martínez, Belén Ruiz-Mezcua Computer Science Department, Universidad Carlos III de Madrid Avda. Universidad 30, 28911 Leganés, Madrid, Spain {lmoreno, pmf, bruiz}@inf.uc3m.es

Abstract. There is not a clear distinction between accessibility and usability for all. This work shows the overlap between usability and accessibility proposing a bridge from the usability heuristics to WCAG 2.0 guidelines. The mapping between some usability and accessibility concepts can be a useful resource to know what aspects of accessibility were collected when the usability is taken into account. Keywords: web accessibility, usability, Heuristic Evaluation

1 Introduction The relationship between accessibility and usability generates discussion due to an unclear distinction between them [1], [2]. Some things are clearly accessibility issues, some are obviously usability; and others are in an area where accessibility and usability overlap. There is not a clear distinction between accessibility for people with disabilities and general usability for all. Accessibility has a technical component and a user interface component. Accessibility of user interfaces can be approached through a usability field. International Organization for Standardization (ISO) 9241-11 defines usability as the "extent to which a product can be used by specified users to achieve specified goals effectively, efficiency and with satisfaction in a specified context of use." [3] Accessibility focuses on including people with disabilities as the "specified users" and a wide range of situations [4], including assistive technologies (ATs), as the "specified context of use". In a simpler way, usability means designing a user interface that is effective, efficient, and satisfying. Accessibility makes sure the user interface is designed to be effective, efficient, and satisfying for more people—especially people with disabilities, in more situations—including with ATs. One way to start looking at the distinction between the two is to categorize interface problems: the usability problems equally impact all users, regardless of ability; that is, a person with a disability is not disadvantaged to a greater extent by usability issues than a person without a disability, whilst the accessibility problems decrease access to a product by people with disabilities. When a person with a

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Lourdes Moreno, Paloma Martínez, Belén Ruiz-Mezcua

disability is at a disadvantage related to a person without a disability then it is an accessibility issue. Apart from this, the distinction is further blurred by the fact that features for people with disabilities benefit people without disabilities because of situational limitations (limitations from circumstances such as environment or device) and additionally accessibility increases general usability. Another point that confuses the distinction is usable accessibility, that is, how usable are accessibility solutions. If a website uses images for navigation and there's no alt text, the site is clearly not accessible, one might say that the site is technically accessible because there is alt text. However, the alt text is so bad that the usability of the site is awful for anyone who relies on alt text. When designing products, it's rarely useful to differentiate between usability and accessibility. However, there are times when such a distinction is important, such as when looking at discrimination against people with disabilities and when defining specific accessibility standards. In some usability test reporting it may be important to distinguish between accessibility and usability problems [5]. Another perspective to consider is the accessibility and usability in the context of a development process. Beside compliance issues at the level of implementation of accessibility standards as WCAG [6], we must guarantee the user satisfaction and usability. In this line, to follow the standard ISO 13407 (Human-centred design processes for interactive systems) [7] is a solution framework, with the use of usability techniques in the web development process [8]. Usability must be considered before prototyping takes place. When usability inspection, or testing, is first carried out at the end of the design cycle, changes to the interface can be costly and difficult to implement, which in turn leads to usability recommendations. Thus, user interface design should more properly be called user interface development [9]. In section two works about Web Accessibility standardization are outlined. Section three describes the overlap between usability and accessibility and provides a bridge from concepts of usability to WCAG 2.0 Success Criteria. The last section includes some conclusions.

2 Web Accessibility standardization. The Web Content Accessibility Guidelines 2.0 (WCAG 2.0) In web accessibility standardization, the W3C must be highlighted along with the Web Accessibility Initiative (WAI) [10]. WAI includes documentation of suggestions on how to use the guidelines in the developments. The Web Content Accessibility Guidelines (WCAG) [6] is one of the most important components, and it is considered to be the official standard in the European Union. These guidelines appear in the majority of legislation worldwide. There are other laws such as Section 508 [11] in the United States. In Spain there is also a standard [12], but all of them are similar to those established by WCAG 1.0 [13].

A bridge to Web Accessibility from the Usability Heuristics

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However, the WCAG do not cover all situations; a study [14] investigated the accessibility of Web sites concluding the need to extend WCAG because, in some cases, pages that did pass that WCAG test were inaccessible in another way and almost certainly would have failed usability test and the resources could be inaccessible. Over the years, two different versions of the WCAG, the WCAG 1.0 and the WCAG 2.0, have been published as W3C Recommendations, with the latter having come into official existence in December 2008. The publication of the WCAG 2.0 became necessary to accommodate not only HTML and CSS, but also scripting and non W3C Web technologies such as RIAs. WCAG 2.0 incorporate techniques of the Accessible Rich Internet Applications (WAI-ARIA) specification for RIA technologies. In this work the new version WCAG 2.0 [15] has been followed. The WCAG 2.0 is built on four basic principles of accessibility: perceivable, operable, understandable and robust. Within these principles, there are guidelines that contain Success Criteria. Each Success Criteria has one of three defined Levels of Conformance (A, AA, AAA). Regarding the fulfillment of these success Criteria, a Web site can have an A, AA, or AAA level of conformance. The priority levels are designed to indicate a Web site’s level of accessibility, with A being the lowest and AAA being the highest.

3 Correspondence between usability principles and WCAG 2.0 In the field of human-computer interaction (HCI), one of the most common informal and popular inspection-based methods for evaluating usability is the Heuristic Evaluation (HE) as described originally by Nielsen and Molich [16] and later refined by Nielsen [17]. The HE is seen as an economical alternative to empirical usability tests involving actual users. HE involves having a small set of evaluators examine the interface and judge its compliance with recognized usability principles (the "heuristics"), the group of evaluators apply heuristics during their independent review of a system. The evaluators explore the system, considering each heuristic in turn in an effort to identify potential usability issues. They are most valuable as an early evaluation technique on a first prototype in an effort to identify the major usability problems. HE method continues to be considered somewhat of a standard in the HCI industry, although many evaluators have found that Nielsen’s original list does not always meet their specific needs. As a result, several modifications of Nielsen's heuristics have been developed over the years in an effort to improve their interpretation, reliability, and adequacy for new technologies. In this work, the criteria of HE method have been used with the approach of "Site Usability Heuristics for the Web" of Keith Instone [18], based on Nielsen [19]. It is a solid reference with other heuristics based on it and it can be adapted to a current project due to the fact that it consists of generic usability principles that can be matched with current criteria.

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A study has been made to find relationships between concepts of accessibility and a very generic usability. We must emphasize that it was not considered the usable accessibility or usability in contexts of use with accessibility barriers, since in this case the conceptual overlap is misleading, as is the usual case to consider providing an alternative text to images (WCAG 2.0 success criteria 1.1.1) as usability criteria. To show the overlap between usability and accessibility issues, Table 1 introduces a correspondence between the criteria of usability heuristics by Nielsen in web environments and the WCAG 2.0 Guidelines. Then, to provide a brief explanation of each heuristic criterion, the related WCAG 2.0 Success Criteria are described. They are denoted by their levels of conformance in parentheses next to the WCAG 2.0 techniques applied in each case. Table 1. Overlap between usability heuristics and WCAG 2.0 guidelines. Usability Heuristics Visibility of system status Match between system and the real world User control and freedom Consistency and standards Error prevention Recognition rather than recall Flexibility and efficiency of use Aesthetic and minimalist design Help users recognize, diagnose and recover from errors Help and documentation

WCAG 2.0 Success Criteria 2.4.2 / 2.4.3/ 2.4.4/ 2.4.6/ 2.4.8/ 2.4.9/ 2.4.10 3.1.2 / 3.1.3/ 3.1.4/ 3.1.5/ 3.1.6/ 3.2.3 1.4.2/ 1.4.4/ 1.4.8/ 2.2.1/ 2.2.2/ 2.2.4 3.2.3/ 3.2.4 3.3.1/ 3.3.2/ 3.3.4/ 3.3.6 1.3.1/ 2.4.2/ 2.4.6/ 2.4.10 2.4.1/ 2.4.3 3.3.3 3.3.5

3.1. Visibility of system status The system should always keep users informed about what is going on, through appropriate feedback within reasonable time. Probably the two most important things that users need to know at your site are "Where am I?" and "Where can I go next?" Make sure each page is branded and that you indicate which section it belongs to. Links to other pages should be clearly marked. Since users could be jumping to any part of your site from somewhere else, you need to include this status on every page. One of the biggest problems for users when browsing the network is the disorientation WCAG 2.0 Success Criteria correspondence: The WCAG 2.0 Guideline 2.4 said: “Navigable: Provide ways to help users navigate, find content, and determine where they are”. Different criteria are specified: Related to documents: 9 2.4.2 (A)/G88 (Providing descriptive titles for Web pages) y H25 (Providing a title using the title element), ARIA 1 (Using Accessible Rich Internet Application described by property to provide a descriptive, programmatically determined label).


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2.4.6 (AA)/G130 (Providing descriptive headings), G131(Providing descriptive labels). 2.4.10(AAA)/G141 (Organizing a page using headings) Concerning the target link: 2.4.3 (A)/G59 (Placing the interactive elements in an order that follows sequences and relationships within the content), H4 (Creating a logical tab order through links, form controls, and objects), C27(Making the DOM order match the visual order) y SCR26(Inserting dynamic content into the DOM immediately following its trigger element), SCR27(Reordering page sections using the DOM). 2.4.4 (A)/ G91 (Providing link text that describes the purpose of a link), G53 (Identifying the purpose of a link using link text combined with the text of the enclosing sentence), ARIA 1 (Using ARIA described by property to provide a descriptive, programmatically determined label). 2.4.9(AAA)/G91 (Providing link text that describes the purpose of a link), C7 (Using CSS to hide a portion of the link text). 2.4.8 (AAA)/ G63 (Providing a site map), G65 (Providing a breadcrumb trail), G128 (Indicating current location within navigation bars), G127 (Identifying a Web page's relationship to a larger collection of Web pages) con H59 (Using the link element and navigation tools).

3.2 Match between system and the real world The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order. On the Web, you have to be aware that users will probably be coming from diverse backgrounds, so figuring out their "language" can be a challenge. ”. Different criteria are specified: WCAG 2.0 Success Criteria correspondence: The related guideline 3.1 specifies: “Readable: Make text content readable and understandable”. We must use a language that is familiar to the user, with simple phrases and concepts. In fact, the WCAG 2.0 guidelines provide how to fix this mismatch between the "conventions of the real world" and the system. The guidelines through techniques indicate that there is a need to offer a mechanism for users to identify what content is unusual or technical words in another language, problems with reading ability, etc, and to provide help about how to access this additional content to understand. 9 3.1.2 (AA)/ H58 (Using language attributes to identify changes in the human language). 9 3.1.3 (AAA)/ G55 (Linking to definitions), G112 (Using inline definitions), G62 (Providing a glossary). 9 3.1.4 (AAA)/ G102 (Providing the expansion or explanation of an abbreviation), G97 (Providing the abbreviation immediately following the expanded form), H60 (Using the link element to link to a glossary), G55 (Linking to definitions), H28 (Providing definitions for abbreviations by using the abbr and acronym HTML elements).

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3.1.5 (AAA)/ G86 (Providing a text summary that requires reading ability less advanced than the upper secondary education level), G103 (Providing visual illustrations, pictures, and symbols to help explain ideas, events, and processes), G79 (Providing a spoken version of the text). 3.1.6 (AAA)/G120 (Providing the pronunciation immediately following the word), G121 (Linking to pronunciations), G62 (Providing a glossary). 3.2.3 (AA)/ G61 (Presenting repeated components in the same relative order each time they appear).

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3.3 User control and freedom Many of the "emergency exits" are provided by the browser, but there is still plenty of room on your site to support user control and freedom. Or, there are many ways authors can take away user control that is built into the Web. A "home" button on every page is a simple way to let users feel in control of your site. Be careful when forcing users into certain fonts, colors, screen widths or browser versions. And watch out for some of those "advanced technologies": usually user control is not added until the technology has matured. One example is animated GIFs. Until browsers let users stop and restart the animations, they can do more harm than good. WCAG 2.0 Success Criteria correspondence: The related guideline 2.2 establishes: “Enough Time: Provide users enough time to read and use content”. It includes different success criteria that indicate characteristics associated and offering the user control in the interaction with web content. The success criteria 1.4.2 is related too, and said: “Audio Control: If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level”. Finally, the Success criteria 1.4.4 and 1.4.8 in relation to CSS implementation ensure the freedom of the user to change the text size, color etc. Different criteria are specified: 9 1.4.2 (A) / G170 (Providing a control near the beginning of the Web page that turns off sounds that play automatically), G171 (Playing sounds only on user request). 9 1.4.4 (AA)/ C28 (Specifying the size of text containers using em units), G178 (Providing controls on the Web page that allow users to incrementally change the size of all text on the page up to 200 percent). 9 1.4.8 (AAA)/ G148 (Not specifying background color, not specifying text color, and not using technology features that change those defaults), H87 (Not interfering with the user agent's reflow of text as the viewing window is narrowed), G175 (Providing a multi color selection tool on the page for foreground and background colors), C20 (Using relative measurements to set column widths so that lines can average 80 characters or less when the browser is resized), G188 (Providing a button on the page to increase line spaces and paragraph spaces).


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2.2.1 (A)/ G198 (Providing a way for the user to turn the time limit off), SCR16 (Providing a script that warns the user a time limit is about to expire), SCR1 (Allowing the user to extend the default time limit). 9 2.2.2(A)/ G4 (Allowing the content to be paused and restarted from where it was paused), G186 (Using a control in the Web page that stops moving, blinking, or auto-updating content), G191 (Providing a link, button, or other mechanism that reloads the page without any blinking content). 9 2.2.4 (AAA)/ G75 (Providing a mechanism to postpone any updating of content), G76 (Providing a mechanism to request an update of the content instead of updating automatically). It would be also related criteria such as 2.3.1 and 2.3.2 which provide restrictions on the use of animated images. In the WCAG 2.0 documentation warns that “since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion”. 3.4 Consistency and standards Users should not have to wonder whether different words, situations, or actions mean the same thing. The site must maintain a consistent structure of content, styles and conventions. The use of style sheets (CSS) helps maintain a graphical design consistency of the site. Conventions should ensure the labeling of links with the same criteria and the links have to be identified in the same way throughout the website. In relation to the standards there is a clear overlap with web accessibility and conformance with the WCAG, which includes an implementation of all recommendations of the W3C on Web technologies ((X) HTML, CSS, XML, SMIL, etc.. ) to ensure compatibility. WCAG 2.0 Success Criteria correspondence: The related guideline 3.2 said “Predictable: Make Web pages appear and operate in predictable ways”, and more specifically the success criteria 3.2.3: “Consistent Navigation: Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages occur in the same relative order each time they are repeated, unless a change is initiated by the user”. Besides, the success criterion 3.2.4 is considered, that is, “Consistent Identification: Components that have the same functionality within a set of Web pages are identified consistently”. Different criteria are specified: 9 3.2.3 (AA)/ G61 (Presenting repeated components in the same relative order each time they appear). 9 3.2.4 (AA)/ H44 (Using label elements to associate text labels with form controls (HTML)), H65 (Using the title attribute to identify form controls when the label element cannot be used (HTML)).

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3.5 Error prevention Even better than good error messages is a careful design which prevents a problem from occurring in the first place, must ensure that instructions are clear to the data entry forms providing mechanisms for identifying required fields. WCAG 2.0 Success Criteria correspondence: The guideline 3.3 said “Input Assistance: Help users avoid and correct mistakes”, it is related and their success criteria are: 9 3.3.1 (A)/ G83 (Providing text descriptions to identify required fields that were not completed), SCR18 (Providing client-side validation and alert (Scripting)), G85 (Providing a text description when user input falls outside the required format or values), G84 (Providing a text description when the user provides information that is not in the list of allowed values). 9 3.3.2 (A) / G131 (Providing descriptive labels AND G89|G83). 9 3.3.4 (AA) y 3.3.6 (AAA) / G98 (Providing the ability for the user to review and correct answers before submitting, G155 (Providing a checkbox in addition to a submit button), G99 (Providing the ability to recover deleted information) and G155 (Providing a checkbox in addition to a submit button). 3.6 Recognition rather than recall Make objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate. For the Web, this heuristic is closely related to system status. If users can recognize where they are by looking at the current page, without having to recall their path from the home page, they are less likely to get lost. Good labels and descriptive links are also crucial for recognition. For the Web, this heuristic is closely related to system status. If users can recognize where they are by looking at the current page, without having to recall their path from the home page, they are less likely to get lost. Good labels and descriptive links are also crucial for recognition. Therefore the success criteria to “Visibility of system status” heuristic is also considered. WCAG 2.0 Success Criteria correspondence: Among the guidelines considered: success criteria 1.3.1, the success criteria 2.4.10 that said “Section Headings: Section headings are used to organize the content”. Others related criteria are: the 2.4.2 (“Page Titled: Web pages have titles that describe topic or purpose”) which indicates that the pages should have title. This approach does not require unique page titles but descriptive and usable ones as success criteria 2.4.6 establishes “Headings and Labels: Headings and labels describe topic or purpose”.


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The related success criteria are: 1.3.1 (A)/ H42 (Using h1-h6 to identify headings), ARIA 1 (Using ARIA described by property to provide a descriptive, programmatically determined label). 9 2.4.2 (A)/G88 (ARIA 4(Using ARIA to programmatically identify form fields as required).Providing descriptive titles for Web pages) y H25 (Providing a title using the title element), ARIA 1 (Using ARIA described by property to provide a descriptive, programmatically determined label). 9 2.4.6 (AA)/G130 (Providing descriptive headings), G131 (Providing descriptive labels). 9 2.4.10(AAA)/G141 (Organizing a page using headings). 9

3.7 Flexibility and efficiency of use Accelerators – unseen by the novice user – may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions. When users do become experts of the program, they may want to speed up some task with shortcuts. This does not mean to change the interface such that tasks can be done quickly but non-intuitively. The principle here suggests that the program should cater to both the inexperienced and the experienced users. WCAG 2.0 Success Criteria correspondence: Advanced users could prefer not to move their hands from the keyboard to the mouse and make use of the keyboard shortcuts to speed up the process. In this point the WCAG 2.0 criteria about keyboard shortcuts are considered. There are Additional Techniques (Advisory) for 2.4.1 that said: Providing keyboard access to important links and form controls (future link), Providing skip links to enhance page navigation (future link), Providing access keys (future link) and Using accessibility supported technologies which allow structured navigation by user agents and ATs (future link). The related success criteria are: 9 2.4.1(A)/G1 (Adding a link at the top of each page that goes directly to the main content area), G123 (Adding a link at the beginning of a block of repeated content to go to the end of the block), G124 (Adding links at the top of the page to each area of the content), H69 (Providing heading elements at the beginning of each section of content), H50 (Using structural elements to group links). Following the 2.4.3 criteria if a Web page can be navigated sequentially and the navigation sequences affect meaning or operation, focusable components receive focus in an order that preserves meaning and operability this applies to the element with control type included in a form. 9 2.4.3 (A)/G59 (Placing the interactive elements in an order that follows sequences and relationships within the content), H4 (Creating a logical tab order through links, form controls, and objects), C27 (Making the DOM order match the visual order) y SCR26 (Inserting dynamic content into the Document Object Model immediately following its trigger element), SCR27 (Reordering page sections using the Document Object Model).

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The WCAG 2.0 Principle 4: “Robust – Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies” is related too because to provide Flexibility and efficiency of use it is necessary to maximize compatibility with user agents and ATs. 3 8 Aesthetic and minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility. Extraneous information on a page is a distraction and a slow-down. Make rarely needed information accessible via a link so that the details are there when needed but do not interfere much with the more relevant content. WCAG 2.0 Success Criteria correspondence: In this case, the next guidelines and success criteria are not directly concerned but if there is some dependence guidelines, the WCAG 2.0 pursue the goal of simplicity, for a better understanding of the user. 3. 9 Help users recognize, diagnose and recover from errors Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution. Errors will happen, despite all your efforts to prevent them. Every error message should offer a solution (or a link to a solution) on the error page. WCAG 2.0 Success Criteria correspondence: The criterion 3.3.3 said “Error Suggestion: If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content”. 9 3.3.3 (AA)/ G83 (Providing text descriptions to identify required fields that were not completed), SCR18 (Providing client-side validation and alert (Scripting)), G85 (Providing a text description when user input falls outside the required format or values), G84 (Providing a text description when the user provides information that is not in the list of allowed values). 3 10 Help and documentation Even though it is better if the system can be used without documentation, it may be necessary to provide support and help documentation. Any information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large. Some of the more basic sites will not need much documentation, if any. But as soon as you try any complicated tasks, you will need some help for those tasks.


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For the Web, the key is to not just slap up some help pages, but to integrate the documentation into your site. There should be links from your main sections into specific help and vice versa. Help could even be fully integrated into each page so that users never feel like assistance is too far away. WCAG 2.0 Success Criteria correspondence: The criterion directly related to is: 9 3.3.5 (AAA) / G71 (Providing a help link on every Web page), G89 (Providing expected data format and example).

Conclusions The mappings among some usability and accessibility criteria have been introduced in this work. This correspondence provides a resource to help professionals to include usability in their Web projects, in such a way that they know what aspects of accessibility were collected. Thus, for each criterion of usability heuristics the guidelines of the WCAG 2.0 with their associated techniques are provided together with useful resources to use at design, implementation and evaluation activities. This work is an additional resource to evaluate the accessibility closely to usability, because the evaluation will be complete only by testing with real users. Acknowledgments This research work has been supported by the Spanish Ministry of Education under the project BRAVO (TIN2007-67407-C03-01) and by The Spanish Centre of Captioning and Audio Description (see http://www.cesya.es ).

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