National Center for Accessible Media
Software and tools
Educational Issues for Students With Disabilities
Accessible interactive software can bring the benefits of multimedia and experimental learning to students who may otherwise be left out. Interactive learning experiences will be especially enriching for students who may otherwise have more limited experiences. Because students with disabilities may not be exposed to as wide a range of activities as other students, accessible software can contribute positively toward filling in some of those gaps.
Low-vision students, however, may still learn from a visual program, provided it is well designed. Software should allow fonts to be adjusted, provide clear contrast for objects that students must locate and manipulate, include keyboard commands to reduce mouse dependence and provide a system cursor that moves with important screen events so that magnifiers can track them.
Benefits of Multimodal Learning
Making software and digital publications accessible to students with disabilities has benefits for other students as well. These benefits are especially important for students learning English as a second language and those with reading difficulty. Accessible textbooks and software often provide multi-modal access to information, combining text with audio.
Tindall-Ford and colleagues showed in several different experiments that when information is presented in audio and visual form, performance on complex tasks is improved (1997).
J.R. Williams reviewed about 100 studies from the literature on use of multimedia in instruction and found that combining visual and verbal information can lead to enhanced comprehension (1998).
Tindall-Ford, S, Chandler, P, & Sweller, J 1997, 'When two sensory modes are better than one', Journal Of Experimental Psychology: Applied, 3, 4, pp. 257-287, Psyc ARTICLES, EBSCO host, viewed 30 October 2012.
Williams J.R. (1998) Guidelines for the Use of Multimedia in Instruction Proceedings of the Human Factors and Ergonomics Society Annual Meeting October 1998 42: 1447-1451,
Williams, T. R. (2000) Guidelines for Designing and Evaluating the Display of information on the Web. By: Technical Communication, 00493155, Aug 2000, Vol. 47, Issue 3
Disabilities, Functional Limitations and Accessibility Tips
Each disability presents unique challenges to computer users.
To support screen reading software, developers can:
- use standard system tools to draw and erase all on-screen text and to display all cursors and pointers.
- use system standard on-screen controls whenever possible.
- define tools in toolbars, palettes, and menus as separate items, and avoid creating single graphics containing multiple objects. When tools and other objects are kept separate, the screen reader is better able to identify and name each tool for the user.
- embed descriptive text in graphic images in such a way as to make the text known to screen-reading software. This addresses the problems that can arise when text is rendered as a graphic image and cannot be read by software.
- assign logical names to controls, even if the name is not visible on the screen. Screen readers can access this information and use it to describe the type and function of the control on the screen.
- track the system cursor with the mouse, even if the cursor is invisible. This allows the screen-reading software to detect the mouse position when customized highlighting or focusing techniques are in use.
- use consistent and predictable screen and dialog layouts.
- avoid the use of "help" balloons that disappear whenever the hot spot, or focus of the mouse, changes. Locking the help balloon in place lets user move the cursor and continue to read the balloon.
- provide keyboard equivalents for all tools, menus, and dialog boxes.
Since screen readers can only read text (or give names to separately identifiable icons or tools), it is a good idea to:
- avoid assigning unlabeled hot spots to pictures for use as controls.
- avoid non-text menu items when possible or at least incorporate visible or invisible text cues to accompany these items. Screen readers can see text even if that text is written to the screen invisibly.
- avoid non-redundant graphic toolbars.
Finally, documentation and training materials are always more accessible when:
- documentation and on-line help can be understood independent of graphics. Text descriptions should stand on their own.
- synchronized audio descriptions are available to play alongside animated graphics or movies.
For People with Low Vision
"Low vision" refers to a range of vision problems including:
- poor acuity, meaning blurred or fogged vision.
- loss of all central vision; the ability to see only the outer ring of the visual field.
- tunnel vision; the ability to see only the center of the normal visual field.
- loss of vision in other parts of the visual field.
- other problems, including night blindness, reduced contrast and sensitivity to glare.
Computer users with low vision often depend on the ability to enlarge or otherwise enhance areas of on-screen information. Screen-enlargement software can be tremendously helpful.
To make on-screen information easier to see, developers can:
- increase the contrast between text and the background.
- place text over a solid-color background. A patterned background can make text harder to discern.
- create consistent layouts for all screens and dialogs within the program.
- provide access to tools via a menu bar.
- follow line-width guidelines when drawing lines on screen. Use the line-width information provided by operating system settings. This will ensure that the learning application will increase all lines proportionally should a user choose to enlarge the view.
- allow the user to zoom in on or magnify portions of the screen.
To make software more compatible with other applications that offer low-vision access features, developers can:
- use the system pointers whenever possible, as well as the system caret or insertion bar, if available.
- include a highlight or focus indicator when dragging the system cursor, even at those times when the cursor is invisible. This adjustment will help screen enlargement software using "pan and zoom" features to track the user's movements more accurately.
- add support for a "high contrast" setting.
- protect users from the need to monitor simultaneously two or more events occurring far apart from each other on the screen.
For People with Language or Cognitive Disabilities
Language and cognitive disabilities are very difficult for developers to address, partly because of the diversity represented in the category. The group includes individuals with:
- general processing difficulties such as mental retardation, brain injury and others.
- specific deficits such as lack of short-term memory, the inability to remember proper names and others.
- learning disabilities such as dyslexia, dyscalculia, dysgraphia, auditory perceptual disabilities, cognitive disorganization, and visual perceptual disabilities.
- language delays.
In addition, the degree of impairment within each of these categories can range broadly, from minimal to severe. In general, software designed to be as user-friendly as possible will improve accessibility for those with language or cognitive impairments.
To improve accessibility for people with language or cognitive disabilities, developers can:
- allow all message alerts to remain on screen until dismissed by the user.
- make language and instructions as simple and straightforward as possible, both on screen and in documentation.
- use simple and consistent screen layouts.
It is important to bear in mind that those with language and cognitive disabilities often have difficulty processing print. To increase accessibility for this population, developers should take steps to make their software compatible with screen-reading software
TOOLS FOR ACCESS
Assistive technology (AT) is an umbrella term used to describe any product or technology-based service that helps disabled people to live, learn, work and enjoy life. In the context of on-line education, assistive technology refers to hardware and software technologies that enable people with disabilities to use computers more effectively.
Screen readers are software products designed for blind users, but they are also useful to users with learning disabilities. Screen readers locate information seen on the computer screen and vocalize it using text-to-speech software and, occasionally, hardware. Most screen readers work in close concert with the operating system, relying on the computer's built-in capabilities. Applications and software that conform to the standards of the operating system are more likely to be accessible. Applications and software that ignore the requirements of screen readers and the operating systems that support them may well prove unusable for some disabled people.
Screen magnifiers are software solutions for people with low vision. These products allow the user to enlarge the size of images and text displayed on screen. Screen magnifiers may also permit the user to change the default colors of the display.
Compatibility between screen magnifiers and software can be a problem for developers. Typical screen magnifiers track the cursor or the active region of the screen and will automatically enlarge that portion of the display. Applications that use a custom cursor design may cause the magnifier to enlarge the wrong portion of the screen. Developers can avoid this problem by relying on standard interface practices, particularly those that apply to cursor control and display.
Equivalent Access Versus Alternative Access
When considering accessibility of learning applications, it is important to understand the differences between two types of access: equivalent and alternative.
Equivalent access provides the disabled user with content identical to that used by the non-disabled user. For the disabled user, however, that content is presented in a different manner. Providing a course textbook in braille format, on audiotape, or in digital format are examples of equivalent accessibility.
Alternative access provides the disabled user with a learning activity that differs from the activity used by the non-disabled user. However, the alternative activity is designed to achieve the same learning objectives. For example, a mobility-impaired student might be given the option of conducting a science experiment in a virtual laboratory, where the levels of dexterity, strength, and physical access are different from those required in a physical laboratory.
There are numerous examples where software developed for alternative access has become the mainstream choice when its value to all learners was recognized. For example, the virtual microscope developed for disabled students by The Open University proved better able to achieve key learning objectives than its mainstream counterpart and so came to be used by all students.