Abstract
The field of human-computer interface design profits from understanding potential users and exploring
difficult design problems. Addressing the design of enabling technology for users with special needs offers
both those advantages. Adapting computer interfaces for access and use by people with various physical and
cognitive impairments exposes many basic human-computer interface design issues. Likewise, these efforts
will result in computer interfaces which are more attractive and usable by all.
Keywords:
disability, human-computer interaction, rehabilitation engineering, users with special needs
Introduction
A common creed of human-computer interface designers is "Know the User". The motivation of this
tutorial is that there may large numbers of potential users that the designer does not know, and may not
normally take into account when designing a system. Those users are people often identified as having
"special" needs. There is an increasing level of recognition that those needs must be met in the design of
interfaces [2][3]. The objective of the tutorial is to identify some of those needs and to describe some of the
possible approaches to meeting them.
The tutorial is structured around the needs of different groups of users: Mobility Impairment, Vision
Impairment, Speech Impairment, Language Impairment, Hearing Impairment, and Cognitive Impairment.
The specific challenges posed to designers are described accompanied by examples of how those can be
met. Often these discussions involve the use of case studies. Of course, all the answers are not known, and
areas requiring further research and possibly innovative solutions are identified.
HCI AND USERS WITH SPECIAL NEEDS
Until the advent of interactive computers in the 1970s, the human-computer interface consisted of punched
card readers and line printers and any interaction was at a distance in time and space, so the study of human-
computer interaction is a relatively young discipline. Until now, it has largely been concerned with the
design and development of interfaces which will be usable by the "average" person. But what is average?
Lacking any theoretical base, interface designers have tended to rely on instinct and introspection. In other
words, the implicit assumption is often that the user resembles the designer. This supposition had led to
interfaces which have been designed for users who are 25-year-old males with a Ph.D. in Computer Science
who are besotted with the technology [5].
Designing for exceptional users has much broader significance than is often assumed. It is fallacious to
think in terms of disabled people and normal people as if they are two clearly distinct groups. We all have a
collection of abilities and weaknesses, furthermore we can all be handicapped by our environment.
The accommodation of users with special needs is part of the discipline of human-computer interaction
because that is where it ought to be. At the same time, though, there is a powerful argument that it is also
important because much of the research and development has a broader significance. Great strides have
been made in research by addressing difficult problems. This method of research is a model that has long
been successfully followed in medicine.
It is often not realized that many everyday products originated as inventions to aid people with disabilities.
Alexander Graham Bell was interested in the design of hearing aids when he developed the telephone. The
cassette tape was originally intended as a format suitable for blind people. The ballpoint pen was designed
for people who lacked the dexterity to use a fountain pen.
The best contemporary example of this approach in practice is the IPSNI project at Dundee University,
Scotland [6]. The aim of this project is to develop a rich, multimedia human-computer interface designed to
maximize the communication ability of an operator with severe physical impairments. But the project is
proceeding in collaboration with an avionics company. The company is tracing all developments in order to
see what discoveries may be of use to pilots, who may be operating within a handicapping environment
(such as blacked out, upside down with limbs weighing three times as much as they normally do).
Interface designers generally rely to a great extent on the adaptability of the user. This assumption explains
why many poor interfaces are still considered usable. But, many of the assumptions about adaptability do
not apply if the users has a disability. Therefore the designer must work harder to create a usable system,
producing a better interface for all users.
Many challenges in addressing the needs of people with physical and cognitive impairments who need or
want to use computers still need to be overcome. These challenges conceal numerous basic issues in human-
computer interface design. For example:
-
Mobility Impairment
-
How can we support efficient interaction with the computer without the use of a standard keyboard or
mouse? What software tools can we provide to minimize the use of difficult devices such as phones, paper,
and environmental controls?
-
Vision Impairment
-
How can we completely transform our extremely visual interfaces into intuitive and efficient nonvisual
interfaces? What is the actual model of interaction independent from graphical and spatial presentations?
[4]
-
Speech Impairment
-
How can we support the generation of conversation at 150 words per minute with, at most, two simple
switch inputs?
-
Hearing Impairment
-
How can we use computers to translate written or spoken English to American Sign Language which is
structurally quite different from Western verbal and written languages? [7]
-
Cognitive Impairment
-
How can we adapt interfaces to suit many cognitive levels, not just adult novice and expert users? [1]
If we address these issues, we will significantly increase the usability and attractiveness of computers for
everyone. We will be many steps closer to reaching goals such as:
- distance working
- novel input via speech, gesture or through everyday devices such as a phone
- the paperless office
- software usable by children and adults, hostile and friendly users, novice and expert
Many possible additions to computer interfaces, such as voice input and virtual reality, while merely
interesting to "normal" users are required by people with disabilities. These additions allow them to perform
daily activities such as working, communication, and controlling their environment. By driving efforts to
reach many goals in HCI design by focusing on real and critical needs, we will produce richer and more
robust designs which will then benefit all users.
References
1. Cress C.J. and Goltz, C. C. (1989) Cognitive Factors Affecting Accessibility of Computers and
Electronic Devices, in Proceedings of RESNA 12th Annual Conference, New Orleans, Louisiana.
2. Edwards, A. D. N (editor), Extra-Ordinary Human-Computer Interaction, New York: Cambridge
University Press (in press).
3. Glinert, E.P. and York, B.W. (1992) Computers and People with Disabilities, in Communication
of the ACM, 35 (5) pp. 32-35.
4. Mynatt, E.D. and Weber, G., "Nonvisual Presentation of Graphical User Interfaces: Contrasting
Two Approaches," in the Proceedings of the 1994 ACM Conference on Human Factors in Computing
Systems (CHI'94)
5. Newell, A. F., (1993) Extra-Ordinary Human-Computer Interaction, in Edwards, A. D. N (editor),
Extra- Ordinary Human-Computer Interaction, New York: Cambridge University Press (in press).
6. Newell, A. F., Arnott, J. L., Cairns, A. Y., Ricketts, I. W. and Gregor, P. (1993) Intelligent systems
for speech and language impaired people: A portfolio of research, in Edwards, A. D. N (editor), Extra-
Ordinary Human-Computer Interaction, New York: Cambridge University Press (in press).
7. Sacks, O. (1989) Seeing Voices, A Journey into the World of the Deaf, University of California
Press, Berkeley.
