Go to previous article.
Go to next article.
Return to 1998 Conference Table of Contents
LED - Catholic University "Nuestra Señora de la Asunción", Paraguay
Fax: (+595-21) 310587
DCC - University of Chile
Fax: (56-2) 6895531
Web usage is being spread to the population of children with disabilities. Since 1993 we are facing the development of many Web sites for people with some disabilities. Web sites and Web access are becoming a common place among people with disabilities. We are also assisting a major concern in terms of straight access of generic Web sites for people with disabilities. We have analyzed current trends and issues in Web design and then adapted them for children with disabilities, considering key areas such as communication, interaction, interactivity, and interfaces. We analyze Web accessibility constrains for children with disabilities. Finally, we illustrate some of the guidelines embedded in Web sites with accessibility for children with disabilities.
In developing computer interfaces for children with physical, sensory or learning disabilities it is important to explore methods that maximize communication and interaction efficiency while attempting to overcome the barriers of the specific impairment. For example, GUI are a widespread user front end for almost any kind of web site. However, it is well known that a gain in efficiency for sighted users could hide strong drawbacks for the community of blind children.
Advances in interactive computer graphics hardware, processing power, sound and video technology, hypertext architectures, multimedia representation, and intelligent agents have created new possibilities for the development of intelligent web sites that support multiple communication channels and may help accessibility. However, particular care must be taken to avoid interfaces that demand too high cognitive and interaction abilities.
In the present work we focus on the design of Web sites that are easier for children with disabilities to use as well as children "without" them by taking their needs into account during the design process.
Providing accessibility means removing barriers that prevent people with disabilities from participating in substantial life activities, including the use of services, products, and information. According to (Bergman and Johnson 1997), accessibility is by definition a category of usability: software that is not accessible to a particular child is not usable by that child. Ideally, this means that children with disabilities can use the Web just as easily, efficiently, and effectively as by children who do not have disabilities.
As with any usability measure, accessibility is necessarily defined relative to user possibilities and needs. For example, graphical user interfaces are not very accessible to blind users, but relatively accessible to deaf users. Moreover, (Vanderheiden 1991) makes a distinction between "direct" access and access through add-on assistive technologies. He describes direct access as "adaptations to product designs that can significantly increase their accessibility..." (p. 2). A major advantage of this approach is that large numbers of users with mild to moderate disabilities can use systems without any modification.
Complementary, it is possible to increase accessibility providing assistive accesses that offer alternative input and output capabilities. For example, screen readers allow blind users to navigate through applications, determine the state of controls, and read text via text to speech conversion. On-screen keyboards replace physical keyboards, and head-mounted pointers replace mice.
More specifically, when we consider Web accessibility, the browser/viewer level plays an important role. According to (Paciello et al. 1996) the browser must: * be able to present the information in different formats required by different users, and * be usable by individuals with a wide range of skills and abilities. To date, there are no browsers and Internet viewers which meet either criterion above across disabilities. However, some example exist for specific access features.
Finally, we emphasize that accessibility provides benefits for a wide range of children, not only for those with some disabilities.
As we see in the previous section, the usability of the Web for children with disabilities is dependent not only on the accessibility of the browser (i.e. Netscape, Internet Explorer), but also on the way information is represented, that is to say, the structure and the nature of the information available on the Web (Gunderson).
Web sites often use fixed modality, assuming that a user is normally sighted and can use upper limbs. Therefore, it is troublesome for children with visual or motor disabilities to adapt such interfaces to their needs.
Many of the Web accessibility problems are related to children who are blind or vision impaired. People with physical disabilities do not have many problems with the design of Web pages due to assistive technologies. If they encounter problems, it is usually with the design of the browser. People with hearing problems only have difficulty if there is important information being presented aurally. As long as all audio information is also visually provided, there is usually no problem in accessing the Web site. Finally, people with cognitive disabilities usually benefit from clearly laid out pages that use plain language and are obvious in their operation.
Currently, the primary output for the Web is highly visual reducing accessibility for a wide number of children with visual impairment. As children with disabilities explore information on the Web they must have access to the information they are exploring in a form that is capable with their perceptual and cognitive capabilities. The current capabilities of browsers allow information and feedback of commands to be presented visually and auditory modes, but it is not currently the children choice to decide which mode they receive; the format of presentation is typically fixed. To appoint this problem, different authors (Kawai et al. 1996, Ramstein et al. 1996, Paciello 1996, Stephanidis and Sfyrakis 1995, Paciello et al. 1996) suggest the needs of new kind of user interface integrating multimodal systems. Such multimodal interfaces allow a greater and more natural communication between the computer and the children. They also allow children to employ the appropriate sensory modalities to solve problem, rather than just using one modality (usually vision) to solve all problems.
(Emiliani and Stephanidis 1995) proposed the classification below about the use of adequate media for special children:
Hereinafter we shall introduce some general consideration related with the nature and structure of information presented using different media.
The use of hearing channels may result very powerful for visual, speech, motor, language and cognitive impaired children.
Aural information may be classified as speech, non-speech and 3D sound. Speech sound may be used as a symbolic input device (through speech recognition interfaces) and also as an output means. However, behind the evident advantages this technology may offers, special care must be taken in order to avoid possible drawbacks (Pitt 1996).
Another useful type of sounds are non-speech ones that let speech-motor and/or language-cognitive impaired children to take advantage from them in temporal tasks, such as selection in a scanning system (Brewster et al. 1996). Moreover, non-speech sounds have several features such as tone, pitch (the sound's frequency) and amplitude that are suitable to represent semantic information about objects or actions related to the adopted metaphor. Tone may be associated to an object or a family of objects (for example, a loud alarm to delimit application boundary or wooden tones for menu items). Pitch may help in the representation of the vertical arrangement of objects. Continuously increasing or decreasing the pitch may be used to give the impression of expansion or reduction.
Finally, 3D sound may be used to represent direction, distance and intensity of the source information.
Text is strongly used in Web sites and may be very useful to alternative representation of information, especially for vision impaired children. In fact, traditional solutions provide visual handicapped children access to computers through text-based interfaces which return information in the form of voice synthesis or Braille while offering keyboard control.
Children who present low vision problems need to be able to adjust text size for easier viewing but special care must be taken to avoid problem with the page layout at browser level.
Use of graphics may decrease cognitive load and increase accessibility for children with some degree of motion impairment. Although, selecting text links can be difficult because of the small target area and dexterity needed to select them with a mouse pointer. Therefore, children with motion impairment, cognitive disabilities or who cannot read well, often find that pictures and graphics/icons make it easier to navigate and comprehend a site. While the use of graphics poses problems for children with visual disabilities, it may make it more obvious for someone else who has difficult reading and/or understanding the content.
This and other different approaches based on the use of adequate media provide the children with more options, it allows them to use any residual hearing or vision, and it is useful to people with language impairments.
In the last years is growing the interest in design accessible Web sites. Interested readers may access different sources such as (Krell 1996) or:
Based on these recommendations and our experiences with visual impaired, down syndrome, and learning disabled children, we will propose some guidelines concerning the design of interfaces that avoid demanding too high cognitive and interaction abilities.
An interesting advantage to have redundant information representation is that children may only opt to download those components they are interested in, saving time (for example, blind will download the audio track while deaf may wish to download video and caption tracks).
Bergman E. & Johnson E., "Towards Accessible Human-Computer Interaction", http://www.sun.com/tech/access/updt.HCI.advance.html, 1997
Brewster S., Raty V. and Kortkangas A., Enhancing scanning input with non-speech sound. In Proceedings of the Second Annual ACM Conference on Assistive Technologies - ASSETS 96 (pp. 10-14), Vancouver - Canada, April, 1996
Emiliani P.L., and Stephanidis C., Multimedia Service and Applications in a Broadband Environment. In Patrick Roe (Ed), Telecommunications for All (pp.205-220), Commision of the European Communities, 1995
Gunderson J., Wold Wide Web Accessibility to People with Disabilities. A Usability Perspective. http://www.staff.uiuc.edu/~jongund/access-overview.html
Kawai S., Aida H. and Saito T., Designing Interface Toolkit with Dynamic Selectable Modality. In Proceedings of the Second Annual ACM Conference on Assistive Technologies - ASSETS 96 (pp.72-79), Vancouver - Canada, April, 1996
Krell M. and Cubranic D., V-Linx: bringin the World Wide Web to sight-impaired users. In Proceedings of the Second Annual ACM Conference on Assistive Technologies - ASSETS 96 (pp. 23-26), Vancouver - Canada, April, 1996
Paciello M.G., Designing for people with disabilities. ACM Interactions (pp.14-16), Vol. 3, No. 1, January, 1996
Paciello M.G., Vanderheiden G.C., Laux L.F. and McNally P.R., Designing the World Wide Web for people with disabilities: a user centered design approach. Proceedings of the Second Annual ACM Conference on Assistive Technologies - ASSETS 96 (pp. 94-101), Vancouver - Canada, April, 1996
Petrie H., Morley S., McNally P., and Graziani P., Accessing Hypermedia Systems for Blind People. Proceedings of the ECART 3 Conference (pp.311-313), Lisbon - Portugal, National Secretariat of Rehabilitation, 1995
Pitt I.J and Edwards A., Improving the usability of speech-based interfaces for blind. Proceedings of the Second Annual ACM Conference on Assistive Technologies - ASSETS 96 (pp. 124-130), Vancouver - Canada, April, 1996
Ramstein C. et al., "Touching and Hearing GUI's: Design Issues for the PC-Access System". Proceedings of the Second Annual ACM Conference on Assistive Technologies - ASSETS 96 (pp. 2-9), Vancouver - Canada, April, 1996
Stephanidis C. and Sfyrakis M., Current trends in man-machine interfaces: potential impact on people with special needs. In Patrick Roe (Ed), Telecommunications for All (pp.205-220), Commision of the European Communities, 1995
Stephanidis C., Savidis A., and Akoumianakis D., Tools for user interfaces for all. In Placencia-Porreo I. and Puig de la Bellecasa R. (Eds.), The European Context for Assistive Technology (pp.167-170), Amsterdam : IOS Press, 1995
Vanderheiden G.C., Accessible Design of Consumer Products: Working Draft 1.6. Trace Research and Development Center, Madison, Wisconsin, 1991.
Vanderheiden G.C, Chisholm W.A., Ewers N., Dunphy S., "Unified Web Site Accessibility Guidelines", Version 7.2, http://www.trace.wisc.edu/docs/html_guidelines/version7.htm, Trace R and D Center, University of Wisconsin - Madison, June 1997
Go to previous article.
Go to next article.
Return to 1998 Conference Table of Contents
Return to Table of Proceedings