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WAI: Strategies, guidelines, and resources to make the Web accessible to people with disabilities

[Draft] Analysis/Requirements and Changelog for [Relationship Between Web Accessibility and Usability]

Latest [Draft] Relationship Between Web Accessibility and Usability

Page Contents

Purpose, Goals, Objectives

From WAI-AGE Project Deliverables: Develop a resource which clarifies issues in the areas of accessibility and usability, with reference to the needs of older Web users.

Notes:

Audience and Messages

Primary:

Secondary:

Open Issues

Notes

References & Resources

Internal references

Outside Resources

Change Requests and Edit Notes

Note: See "References" section above for meeting minutes and e-mail comments.

21 Oct 2009 (WAI-AGE teleconference discussion)

16 Oct 2009 (EOWG teleconference discussion)

Archive

From Understanding Web Accessibility

The International Organization for Standardization (ISO) defines usability as the “extent to which a product can be used by specified users to achieve specified goals effectively, efficiently and with satisfaction in a specified context of use” [X]). Using this definition, accessibility focuses on:

Put more simply, usability means designing your website to be effective, efficient, and satisfying. Accessibility makes sure it is effective, efficient, and satisfying for more people, especially people with disabilities, in more situations—including with assistive technologies.

Looking at definitions is easy. In practice, the relationship between accessibility and usability is more complex. For some people, it's a hotly debated topic. For most people, it's not an issue at all: When designing websites, it is rarely useful to differentiate between usability and accessibility.

However, there are times when the distinction between accessibility and usability is important, such as when looking at discrimination against people with disabilities and when defining specific accessibility standards. Yet the distinction is a common debate when defining accessibility standards such as WCAG. It is not clear what should be included in accessibility standards and what is purely usability and should not be included in accessibility standards.

One way to start looking at the distinction between the two is to categorize interface problems:

The distinction between usability and accessibility is especially difficult to define when considering cognitive and language disabilities. Many of the accessibility guidelines to improve accessibility for people with cognitive disabilities are the same as general usability guidelines. The distinction is further blurred by the fact that features for people with disabilities benefit people without disabilities because of situational limitations (that is, limitations from circumstance, environment, or device—such as using the Web on a mobile phone in bright sunlight with one hand because you're holding a sleeping baby with the other), and accessibility increases general usability.

Another point to cloud the distinction is “usable accessibility”—how usable are accessibility solutions. For example, if a site uses images for navigation and there's no alt text, the site is clearly not accessible. If the site has frustratingly verbose alt text (such as "This image is a line art drawing of a dark green magnifying glass. If you click on it. . ."), 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 the alt text (which won't happen when you understand accessibility issues and include people with disabilities in your project).

There can be problems when people don't understand the issues around the distinction between usability and accessibility. For example, if a study reported that sites were not accessible but the problems were general usability issues (that impact all users, not just users with disabilities), the study could report incorrect conclusions about accessibility guidelines. Academic discussions of accessibility and usability can actually harm the cause of accessibility if they are not presented carefully for people who don't understand the complexity of the issue.

The bottom line on the issue of the relationship between accessibility and usability can be summarized as:

Using both UCD and WCAG as the basis for addressing accessibility ensures that the broad range of issues is covered well, at both the technical level and the user interaction level. You should be able to get most of what you need from WCAG. Involving users and using the UCD approach makes it easier and better.

From "Distinguishing Between Accessibility and Usability Issues"

There is not a clear distinction between accessibility for people with disabilities and general usability for all. Some things are clearly accessibility; some are clearly usability; and many things are in a gray area where accessibility and usability overlap.

One way to start looking at the distinction between the two is to categorize interface problems:

The distinction between usability and accessibility is especially difficult to define when considering cognitive and language disabilities. Many of the accessibility guidelines to improve accessibility for people with cognitive disabilities are the same as general usability guidelines. The distinction is further blurred by the fact that features for people with disabilities benefit people without disabilities because of situational limitations (that is, limitations from circumstance, environment, or device—such as using a mobile phone in bright sunlight with one hand because you're holding a sleeping baby with the other), and accessibility increases general usability.

Another point to cloud the distinction is “usable accessibility”—how usable are accessibility solutions. For example, if a website uses images for navigation and there's no alt text, the site is clearly not accessible. If the site has frustratingly verbose alt text (such as "This image is a line art drawing of a dark green magnifying glass. If you click on it, it will take you to the Search page for this Acme Company website" instead of just "Search"), 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.

Distinguish between usability and accessibility issues, as appropriate. 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.

When usability test reports are used internally to improve the usability of the product for all users, it is usually not necessary to distinguish between usability and accessibility issues. However, when usability test reports make statements about accessibility, it can be vital to distinguish between usability and accessibility issues.

There can be problems when people don't understand the issues around the distinction between usability and accessibility.

A research study reported results on website accessibility without clearly separating general usability issues not related to accessibility. Because usability issues were mixed with accessibility issues, the study reported incorrect conclusions about web accessibility guidelines.

Academic discussions of accessibility and usability can actually harm the cause of accessibility if they are not presented carefully for people who don't understand the complexity of the issue.

From Accessibility in User-Centered Design: Background

What is Accessibility?

Accessibility basically means that people with disabilities can use a product. More specifically, accessibility is making user interfaces perceivable, operable, and understandable for people with a wide range of abilities. It encompasses all disabilities, or functional limitations, including visual, auditory, physical, speech, cognitive, and neurological disabilities. This includes temporary conditions, such as when you break your arm, or lose your glasses.

Accessibility also makes products more usable by people in a wide range of situations. Situational limitations come from circumstances, environments, and conditions, and can affect anybody—that is, people without disabilities as well. For example, situational limitations include using the Web on a mobile phone when your eyes are busy (such as driving), in bright sunlight, in a dark room, when your hands are full, in a quiet environment (where you don't want it to make noise), in a noisy environment (where you can't hear well), and in an emergency (when you may not be thinking clearly).

Thus, while access to people with disabilities is the primary focus of accessibility, it also benefits people without disabilities and organizations that develop accessible products because designing for functional limitations overlaps with designing for situational limitations.

For a more comprehensive introduction to web accessibility, including specific examples of how web accessibility benefits organizations and individuals, see the Understanding Web Accessibility book chapter.

Accessibility related to usability

Accessibility has a technical component and a user interface component. Accessibility of user interfaces can be approached through usability. 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." [2] Accessibility focuses on including people with disabilities as the "specified users" and a wide range of situations, including assistive technologies, as the "specified context of use".

Put more simply, 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 assistive technologies.

Accessibility is about designing user interfaces so that more people can use your product effectively in more situations. [3]