Assistive Technologies

  1. What is assistive technology?
  2. What is a screen reader?
  3. Where can I get a screen reader?
  4. How can a sighted Web developer benefit from using a screen reader?
  5. Why is so much attention given to Web accessibility for screen readers?
  6. How can I determine the order in which a screen reader will read a Web page, a form, or a table?
  7. How do screen readers indicate text formatting?
  8. How are JAWS and Window-Eyes different?

  1. What is assistive technology?
  2. Users with disabilities frequently rely on hardware and software to access Web content. These tools, known as assistive technologies, range from screen readers to touch screens and head pointers.

    Blind users of the Web frequently use software called a screen reader to read the contents of a Web page out loud. Two common screen readers are JAWS from Freedom Scientific and Window-Eyes from GW Micro. Screen readers enable users to receive the on-screen content of a Web page through synthetic speech or braille output; however, a screen reader can read only text, not images or animations. It is recommended that images and animations be assigned text descriptions that screen readers can read. These text descriptions are called alternative text, or ALT-text.

    Users with mobility impairments may rely on the keyboard instead of the mouse to navigate Web pages and may also use voice recognition software like Dragon Naturally Speaking. For individuals with nerve damage, arthritis, or repetitive motion injuries, use of the mouse may not be comfortable or possible. Using only Tab and Enter on the keyboard, it is possible for these individuals to navigate a page with ease. Many users of the Internet have the capability to navigate without a mouse and are simply unaware of it. In Microsoft Internet Explorer, pressing Tab moves the focus of the browser among all available links on a page. (The dotted lines around links in Internet Explorer are an indicator of this capability.) Pressing Enter activates links, much like clicking a mouse.

    In some cases, users may employ touch screens, head pointers, or other assistive devices. A touch screen allows an individual to navigate the page using her or his hands without the fine-motor control required by the mouse. A head pointer is simply a stick, placed in a person's mouth or mounted on a head strap, that the person uses to interact with a keyboard or a touch screen.

    In these cases, it is very important that essential components of the page work without a mouse. Rollovers, drop-down lists, and interactive simulations are all examples of elements that typically depend on the mouse for user interaction. The designer or developer of these elements must ensure that keyboard-defined events are included along with mouse-defined events. A quick test using the keystrokes available in Internet Explorer can provide a valuable glimpse of the difficulties a Web page may present for users with disabilities.

  3. What is a screen reader?
  4. A screen reader is software that converts information on the computer screen to audible spoken language.

    A screen reader tracks the focus of the user's navigation, converts the screen contents into a string of text, and then sends this string to a speech synthesizer to be spoken. For example, when a user presses the Down Arrow key in a word processing document, the blinking cursor moves to a new line. The screen reader considers the new line to be the pertinent information, and so sends it to the speech synthesizer.

    In addition to tracking the screen focus, the screen reader has an enormous assortment of actions it can perform when the user issues keystroke commands, such as reading a given rectangular area of the screen, reading text with a particular color combination, or reading the title and maximized, minimized, or normal status of the current window. The user can also customize how the screen reader behaves in a particular application, instructing it to announce font changes or new text appearing in particular areas of the screen, or specifying which punctuation characters should be spoken.

    Screen readers can generally anticipate what the user wants to hear without the user having to memorize more than a few keystroke commands. The learning curve to become truly proficient, however, is both long and steep. Synthetic speech also takes some getting used to. Still, a novice can begin using the software to surf the Web almost immediately.

  5. Where can I get a screen reader?

    Two of the most commonly used screen readers are JAWS for Windows and Window-Eyes Professional, both available only for PCs.

    JAWS, an acronym for "Job Access With Speech," is a popular screen reader for the Windows operating system. JAWS for Windows is manufactured by Freedom Scientific ( ). The "home" version runs under Windows 9x, ME, and XP Home Edition, while the "Professional" license enables additional support for Windows NT/2000/XP-Professional. The downloadable JAWS software can run for forty minutes as a demo if the user has not purchased an authorization key.

    Window-Eyes Professional, by GW Micro, is another popular screen reader that operates under Windows XP Home and Professional, 2000, or NT. The Window-Eyes "Standard" version runs under Windows 9x/ME. A 30-minute demo version is available for download.

  6. How can a sighted Web developer benefit from using a screen reader?
  7. Testing with a screen reader is the best way to be confident that a Web site is accessible. Screen readers are wonderful at revealing mistakes that often go visually undetected! Some examples include coding errors, especially regarding dynamically generated code that a screen reader might read in the wrong order or fail to detect; images with missing ALT-text or with inadequate descriptions like "click here"; spelling mistakes like "accessibilty" that might look right but sound very wrong when spoken by JAWS; and grammatical errors like "accessibility make it easy read the page for everyone!"

  8. Why is so much attention given to Web accessibility for screen readers?
  9. Spatial layout and graphical style are primary means to convey information on the World Wide Web. Sighted users know what information to attend to, often because of its appearance, an eye-catching image, or its placement on the page. Speech, by contrast, is strictly linear.

    The linear constraints of screen readers make them good mechanisms for testing the accessibility of a Web site. Accessibility for screen readers demands the strictest separation of Web content from its style of presentation. This separation makes Web documents more flexible for different devices or Web browsers, regardless of screen size, colors, or the browser's ability to display graphics. When a page's content has a linear structure, it makes sense when the screen reader reads top-left to bottom-right. This linear structure creates benefits that extend to users who use screen magnification software like ZoomText, people with learning disabilities, and people who rely on slow forms of input like on-screen keyboards or mouth sticks. Finally, screen readers rely exclusively on keyboard input-no mouse! Windows includes several keystrokes that non-disabled users may not be aware of, and assistive technologies add more. Keyboard access to all the functionality of a Web site is important for people who are blind, for people who use alternative input devices that transmit keystroke equivalents to the computer, and of course for people without disabilities who prefer to use the keyboard.

  10. How can I determine the order in which a screen reader will read a Web page, a form, or a table?
  11. In most cases, screen readers speak all page elements in the same order as they appear in the document's source code, left to right and top to bottom.

    If you are not using a screen reader, you can use the mouse to see the reading order. When you click and drag, the order in which text, table cells, and images are highlighted is the order in which a screen reader will read them.

    Alternatively, you can use an accessibility checker called The Wave to determine the order in which the text will be read.

  12. How do screen readers indicate text formatting?
  13. By default, Window-Eyes and JAWS will raise the pitch of capital letters when spelling a word or moving the cursor over a capitalized letter. Users can select to have the screen reader announce "cap" and "all caps" before capitalized words when reading by line, sentence, or document. Some speech synthesizers may provide different options, such as raising the pitch of capitalized or all-caps words when reading by line.

    Users can also select to hear specifics of typeface, font size, and attributes such as bold or underlining, plus foreground and background colors. Colors are more complex, since there are 16,581,375 possible color combinations available to Web authors. Colors may be announced as RGB numeric values or as standard named colors. These options are turned off by default and only a few very proficient users will turn them on, and then only when they want to check something specific. For example, when a form field with invalid input is distinguished only by the color red, people who use screen readers will probably not be able to submit the form successfully.

  14. How are JAWS and Window-Eyes different?

    The most basic distinction between JAWS for Windows and Window-Eyes is that JAWS is programmable using its own scripting language. This means that advanced users can precisely control when and what JAWS says, and how it interacts with the user in any application. Window-Eyes, on the other hand, does not use scripting, but provides comparatively quick ways to customize how it behaves in applications. Window-Eyes is sometimes considered to be more stable and responsive than JAWS, and can sometimes access screen information that JAWS does not detect. JAWS remains the "industry standard," in part because scripting enables much greater functionality in commonly used programs such as Microsoft Office.

    Although both screen readers allow users to map all their commands to any key combinations, the default keystrokes are generally different. Users familiar with one program will have to frequently look up commands (or remap them to familiar keys). The differences can make it difficult for JAWS users to use Window-Eyes or vice-versa, since issuing particular keyboard commands becomes second nature.

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Page Reviewed/Updated: 3/22/2012