- From: Gregg Vanderheiden <gv@trace.wisc.edu>
- Date: Fri, 12 May 2000 00:12:32 -0500
- To: "GL - WAI Guidelines WG \(E-mail\)" <w3c-wai-gl@w3.org>
>From the web page
http://www.wid.org/tech/telecom
TELECOMMUNICATIONS PROBLEMS AND DESIGN STRATEGIES FOR PEOPLE
WITH COGNITIVE DISABILITIES
Annotated Bibliography and Research Recommendations
Introduction
Chapter 1. Background
Chapter 2. Guidelines and Strategies
Chapter 3. Cognitive Abilities and Disabilities
Chapter 4. Specific Cognitive Disabilities
Chapter 5. Toward Better Guidelines and Strategies: Closing the
Gap
Chapter 6. Recommendations for Future Research
Appendix 1: References
Appendix 2: Annotated Bibliography
This report is also available as a PDF download. In order to
view and/or print the downloaded PDF file you will need to have
the Adobe Acrobat Reader Software which you can get here. To
open the compressed version you will need a program like WinZip
or StuffIt.
* Telecommunications Report PDF [2.9MB]
* Compressed version Telecommunications Report PDF.zip [1.7MB]
WORLD INSTITUTE ON DISABILITY
August 16, 1999
Report and Research Recommendations by
Ellen Francik, Ph.D.
Annotated Bibliography by
Suzanne Levine, M.A.,
Shelley Tremain, Ph.D.,
Ed Roberts Post Doctoral Fellow,
and Ellen Francik
Project Director
Betsy Bayha, Director, Technology Policy
World Institute on Disability
----------
ACKNOWLEDGMENTS
Research, publication and distribution of this document is made
possible through the Rehabilitation Engineering Research Center
on Universal Telecommunications Access, a partnership between
Gallaudet University, the World Institute on Disability and the
Trace Research and Development Center at the University of
Wisconsin. Funding is provided by the U.S. Department of
Education, National Institute on Disability and Rehabilitation
Research Grant H133E50002. Opinions expressed in this document
are not necessarily those of the funding agency.
Additional funding for research was provided by the Ed Roberts
Fellowship Program, a collaboration between the University of
California, Berkeley and the World Institute on Disability under
a grant funded by the U.S. Department of Education, National
Institute on Disability and Rehabilitation Research, Grant
H133P50005.
SUMMARY
This report summarizes a literature review on use of
telecommunications by people with cognitive disabilities.
Section 1 of the report describes the research methodology.
Section 2 discusses general accessibility guidelines, identifies
those that appear to be relevant to cognitive disabilities, and
notes some of the barriers to usage they are designed to
overcome. It outlines four classes of universal design
strategies designers might employ:
* Redundant, user-controlled modality of information.
* Streamlined, user-controlled amount and rate of information.
* Procedural support.
* Content organization.
Section 3 describes underlying cognitive abilities and notes
some of the functions or user tasks which they may affect.
Section 4 reviews detailed findings from the literature for some
specific disabilities: age-related cognitive disabilities,
learning and language disabilities, brain injury, and mental
retardation. Section 5 summarizes research that relies on very
detailed analyses of tasks, cognitive abilities, and interface
design changes.
Section 6 concludes by suggesting areas for further research.
Better design leads to better guidelines, and so the first
priority is the continued development of "reference designs,"
sample accessible telecommunications devices and services. Other
areas of research include:
* Layered or streamlined functionality.
* Training, procedural support, and problem-solving.
* Better user descriptions to help designers envision actual
product use by people with cognitive disabilities.
* Increased attention to human performance modeling,
developing parameters that represent people with
disabilities.
* Correlative research, tying design to specific cognitive
abilities, which will benefit the nondisabled population as
well as those with cognitive disabilities.
* A unifying framework, or "roadmap," to better link
theoretical and practical work for designers' benefit.
The appendix of this report contains an annotated bibliography.
----------
1. BACKGROUND
This report fulfills a deliverable of Rehabilitation Engineering
Research Center on Universal Telecommunications Access by the
World Institute on Disability (WID). It summarizes a literature
review on use of telecommunications by people with cognitive
disabilities.
This report discusses barriers to usage that people with
cognitive disabilities experience with telecommunications
products and services. It also discusses universal design
strategies that designers might employ, and interface design
issues.
It concludes with recommendations of studies that would lead to
improved design and further guideline development.
The methodology of the research is described below. The
bibliography and annotations are in Appendices 1 and 2.
1 . 1 . METHODOLOGY
This project began with a review of resource literature and
other print resources; to seek information about problems of and
strategies used by people with cognitive disabilities.
For this project, cognitive disability is defined as those
cognitive functional limitations associated with aging, learning
disabilities, mental retardation and traumatic brain injury. The
functional limitations associated with these disabilities can
vary widely, from severe retardation, to memory difficulties, to
the absence or impairment of specific cognitive functions,
particularly language (Vanderheiden and Vanderheiden, 1991).
They also may include difficulties in perception,
problem-solving, conceptualizing, reading difficulties,
thinking, and sequencing (Trace Research and Development Center,
1996d, EITAAC Final Report, 1999).
Search terms used to describe these functional limitations
follow:
* Alzheimer's
* Attention Deficit Disorder/Attention Deficit
* Hyperactivity Disorder
* Cognitive Disability
* Dementia
* Developmental Disability
* Dyslexia
* Epilepsy
* Intellectual Disability
* Learning Disability
* Mental Retardation
* Mental Handicap
* Stroke / Aneurysm
* Traumatic Brain Injury
Telecommunications technology is broadly defined as those
technologies requiring or supporting interaction with a person
or information source. Examples would include equipment,
software and interactive services such as telephones, pagers,
Automatic Teller Machines, kiosks, and the Internet. Technology
terms used in the search are as follows:
* Appliances
* Automated Voice Processing
* ATMs
* Caller ID
* Cellular Phones
* Computer Interfaces
* Consumer Electronics
* Pagers
* Internet
* Telecommunications
* Telephones
* Voice Mail
* Wireless Phones
* World Wide Web
The study began with a list of key words related to cognitive
disability, telecommunications and engineering design generated
by project staff. The engineering design terms used were:
* Access
* Assistive Technology
* Cognitive Load
* Design Standards
* Human Factors
* Input / Output
* Interface Design
* Interpretation of Information
* Navigation
* Physical Access
* Universal Design
* Way Finding
From this list of terms, staff assembled a matrix of the terms
to assist in database searches. An initial search using this
matrix was conducted on-line through 14 different databases.
These databases were:
* Applied Science and Technology Abstracts,
* ArticleFirst, Online Computer Library Center, Inc., Dublin,
OH
* Business Dateline, UMI Provides, Ann Arbor, MI
* Business and Industry, Responsive Database Services, Inc.,
Beachwood, OH
* ContentsFirst, Online Computer Library Center, Inc., Dublin,
OH
* Educational Resources Information Center, Rockville, MD
* Government Printing Office, Washington, D.C.
* PapersFirst, Online Computer Library Center, Inc., Dublin,
OH
* INFO TRAC, health and diseases database
* MAG INDEX, magazine database
* SocioAbs, Cambridge Scientific Abstracts
* Social Science Abstracts, H.W. Wilson Co., Bronx, NY
* Wilson Business Abstracts H.W. Wilson Co., Bronx, NY
* WorldCat Database, Online Computer Library Center, Inc.,
Dublin, OH
In addition to literature databases the World Wide Web (WWW, or
Web) was used as a resource. Searches were conducted at more
than 22 websites, including disability-related sites as well as
some computer research sites. This proved to be fruitful -
especially sites from conferences where presenters posted their
papers on-line, as well as the Trace Research and Development
Center site and Learning Disabilities on-line sites where
researchers have posted their work. The Web sites searched were:
* Association for Computing Machinery - www.acm.org
* California State University, Northridge Center on
Disabilities -www.csun.edu/cod/
* California State University, Northridge Papers -
www.dinf.org/csun_98/
* Center for Accessible Technology - www.el.net/CAT
* Center for Applied Special Technology (CAST) - www.cast.org
* Closing the Gap - www.closingthegap.com
* Disabilities Opportunities Internetworking Technology
(DO-IT) - weber.u.washingtion.edu/~doit/
* Epilepsy Foundation - www.efa.org
* Job Accommodation Network - janweb.icdi.wvu.edu
* LD OnLine: Learning Disabilities Information and Resources
www.ldonline.org
* Learning Disabilities Association - www.ldanatl.org
* National Academy Press - www.nap.edu
* National Information Center for Children and Youth with
Disabilities -www.nichcy.org
* National Institute on Disability and Rehabilitation
* Research - www.ed.gov/offices/osers/NIDRR
* National Research and Development Centre for Welfare and
Health (STAKES) - www.stakes.fi/cost219/COSB224.HTML
* New England Medical Center. Department of Physical
* Medicine and Rehabilitation Research and Training Center in
Rehabilitation and Childhood Trauma.
www.nemc.org/rehab/homepg.htm
* Parents and Educators Resource Center - www.perc-schwabfdn.
org
* Research Group on Rehabilitation and Independent Living -
www.Isi.ukans.edu/rtcil/RGRIL.HTM
* TRACE Research and Development Center -trace. wisc.edu
* Traumatic brain injury bibliography of web links.
members.aol.com/TBISCIProj/ISBISCIproj.html
* World Health Organization -
www.who.org/whosis/icidh/icidh.htm
* World Wide Web Consortium (W3C) - www.w3.org
The Job Accommodation Network (JAN) of the President's Committee
on Employment of People with Disabilities was contacted for
literature and case histories of people with cognitive
disabilities requiring modification in the work place in order
to use telecommunications technology.
Shelley Tremain, the 1997 Ed Roberts Postdoctoral Fellow at WID
and UC-Berkeley, visited the office of the Ontario Brain Injury
Association (OBIA) in St. Catharines, Ontario, Canada, in order
to conduct a search of databases housed there, as well as OBIA's
reference library.
Consultant Kevin O'Brien contributed several key articles from
the literature on human-computer interaction, cognitive aging,
and individual differences.
1.2. RESULTS
There are 111 documents in the bibliography. The documents can
be grouped as follows:
* 23 discuss characteristics of people with cognitive
disabilities or more general human cognitive capabilities.
* 55 cover products currently used by people with cognitive
disabilities or evaluate particular interfaces as a function
of cognitive ability.
* 5 hypothesize uses of certain technologies.
* 28 contain design guidelines (including cross-disability
guidelines) or other organizing frameworks.
More information was found on technology for people with
learning disabilities than for people with aging-related
cognitive disabilities. Technology for people with traumatic
brain injury or mental retardation is even less frequently
documented. Also, there is significantly more information about
computers than about telephones or other telecommunications
equipment.
1.2.1. User Characteristics
The group of documents addressing user characteristics is
discussed at length in Section 3. Of the documents not cited
there, several are worth mentioning. LaPlante and Carlson (1996)
summarize US survey data on prevalence and causes of disability.
Estimates are provided for mental retardation and learning
disabilities, but population estimates of other types of
cognitive disabilities are hard to extricate from the data
because categories are based on medical conditions that do not
uniformly result in cognitive limitations. Brodin (1992) gives
estimates of the prevalence of mental retardation in the world,
Europe, and the US. She also defines some general requirements.
The American Association on Mental Retardation (1999) defines
mental retardation and provides other background at their Web
site. Vanderheiden and Vanderheiden (1991) summarize cognitive
functional disabilities as part of a larger survey. Several
sources give definitions and statistics on learning
disabilities, including Cramer and Ellis (1996), Hammill et al.
(1987), Johnson and Blalock (1987), Reid et al. (1991), and Shaw
et al. (1995).
Articles on aging are discussed in section 4. Charness and
Bosman (1992) cover perceptual and physical as well as cognitive
aspects of aging. Park (1992) emphasizes applied cognitive aging
research. West (1989) and Yesavage, Lapp, and Sheikh (1989)
review the literature on mnemonic training and discuss
underlying cognitive abilities.
1.2.2. Product Use and Interface Evaluation
A large group of documents covers assistive technology rather
than universal design. Assistive technology refers to add-on
devices or specialized equipment which provide access, whereas
universal design describes access features that are fully
integrated into off-the- shelf products. This group is also
marked by the prevalence of documents about accommodations for
learning disabilities. Surveys include those by Day and Edwards
(1996), the Job Accommodation Network (1997c), Lewis (1998),
MacArthur (1994), Raskind and Higgins (1998), Raskind, Higgins,
and Herman (undated), Raskind and Scott (undated), Raskind and
Shaw (1988), and Riviere (1996).
More general surveys on assistive technology and
telecommunications usage include those by the Alliance for
Technology Access (1996), the Job Accommodation Network (1995;
1997 a, b, d), and Vanderheiden (1998b). Mann (1996) discusses
telephone accommodations for disabled elders and briefly
mentions memory dial buttons, including those with pictures, for
people with cognitive disabilities.
Bergman and colleagues (1991a, b; Bergman and Kemmerer, 1991;
Bergman, 1998) provide short- and long-term evaluations of a
computer environment customized for people with brain injury.
Cole and Dehdashti (1998) summarize their work on a comparable
system. Brodin and colleagues (1994; Brodin and Magnusson 1992
a, b) examine the benefits of videophones for people with
moderate retardation or aphasia.
Glisky (1992; Glisky, Schacter, and Tulving 1986) demonstrates
the benefits of an adaptive training system to teach computer
skills to people with aphasia.
Individualized solutions - customized technology made to
accommodate one particular person's disability - are presented
by Chute (1988), Haugen (1996, 1997), Hendrix and Birkmire
(1998), Hubble Dahlquist (1998), Kirsch et al. (1992), Kreutzer
et al. (1989), Levinson (1997), and Steele et al. (1991).
The remaining documents focus more on universal design - how
easy mass market interfaces are for people of varying cognitive
abilities. The Trace Research and Development Center has done a
series of grids analyzing problems that people with disabilities
have with public phones, automatic teller machines, and public
transport (1996 a, b, c). These analyses include dyslexia,
language impairment, intellectual impairment and reduced motor
coordination. Trace has also published a reference design (1999)
showing how a mass market wireless phone can be made compliant
with Federal accessibility guidelines.
Cress and colleagues (Cress and Tew, 1990; Cress, French, and
Tew, 1991; Cress and French, 1992, 1994) analyze the cognitive
complexity of computer input devices and evaluate their use by
adults, normally developing children, and children with mental
retardation.
Rogers and Fisk (1997) report difficulties older users have with
automatic teller machines, and the effects of various forms of
tutorials on users' performance and willingness to use the
machines. Echt, Morrell, and Park (1998) also look at training
materials when comparing young-old and old-old adults'
acquisition of basic computer skills. Morrow and associates
propose effective text-and-illustration formats for older
adults' written medication instructions (Morrow et al., 1998b;
Morrow and Leirer, in press). They also examine the effects of
organization, enforced repetition, and optional repetition in
automated appointment reminders delivered as phone messages
(Morrow et al., 1995; 1998b). Park (1992) includes other applied
studies in her review of cognitive aging research.
One set of these documents looks at the relationship between
cognitive abilities and computer system design among people
without disabilities. The seminal articles here are by Egan and
Gomez (1985; Egan, 1988). They demonstrate the nuances of
assessing individual differences, doing a sufficiently detailed
task analysis to see where those differences matter, and
redesigning the interface to minimize age, aptitude, and
experience disadvantages. Sein et al. (1993) and Allen (1994)
contribute other studies in this vein. Dillon and Watson (1996)
provide historical background for this work. Anderson et al.
(1995) take a different approach to accommodating individual
differences by putting an adaptive user model at the heart of
their instructional software.
1.2.3. Hypothetical Applications
The third group of documents discusses hypothetical
applications, that is, untested proposals of particular
technologies to accommodate people with cognitive disabilities.
Three of these stand out. Barker (1998) describes general access
strategies for WebTVT, and notes its flexible display and
ability to connect alternative input devices. Crandall, Bentzen,
and Myers (1998) tested Talking Signsr with people with visual
disabilities, and note the signs' potential use for people with
cognitive disabilities who cannot read text. Vanderheiden,
Mendenhall, and Andersen (1993) discuss the benefits of virtual
reality for people who need help with written sequences, or
people who need a more forgiving environment in which to
practice life skills.
1.2.4. Guidelines and Frameworks
The fourth group discusses guidelines and frameworks. Until
recently, design guidelines for cognitive disabilities have
tended to be general. Exceptions are Cress and Goltz (1989) and
Vanderheiden and Vanderheiden (undated). The general usability
standard from the American National Standards Institute,
ANSI/HFES 200 (Blanchard, 1997), contains a section on
accessibility but only in broad terms without reference to
specific disabilities or specific modifications. The Electronic
Industries Association's guide (1996) is more specific about the
design of consumer equipment. The World Wide Web Consortium's
Web Access Initiative (1998) provides guidelines for alternative
visual and auditory displays, and proposes a style sheet
standard. Nielsen (1996) discusses Web design for people with
cognitive disabilities and Rose (1998) describes universal
design strategies for K-12 curriculum development with specific
examples of cognitive supports.
The efforts of the Telecommunications Access Advisory Committee
(1997, 1999), and its successor, the Electronic and Information
Technology Access Advisory Committee (1999) have provided more
specific design guidance. The TAAC's working draft of
accessibility guidelines and strategies (1999) is currently the
most complete, product-independent list available. It compiles
practical ideas for designers to try.
The EITAAC report (1999) is notable for two things. First, it
contains some technology-specific standards and implementation
details. Second, it sets an accessibility goal. A person with a
disability should be able to "perform the same tasks, access the
same information, with the same approximate ease and in the same
approximate time and at the same cost" as someone without a
disability (4.3.1). This implies that designers should
especially pursue solutions that help to close the gap in task
performance between those with (cognitive) disabilities and
those without. Vanderheiden and colleagues have developed a
cross-disability accessible user interface framework for kiosks
and other consumer devices (Law and Vanderheiden, 1998;
Vanderheiden, 1997; Vanderheiden, 1998c; Vanderheiden, Law, and
Kelso, 1998). The emerging Digital Talking Book standard
(DeVendra, 1998; Kerscher and Hansson, 1998) which delivers
books in a range of formats and a variety of navigation options
may also provide models for creating access to printed materials
for people with cognitive disabilities.
The use of a functional grid for product evaluation is
demonstrated by Kaplan, De Witt, and Steyaert (1992) and the
Trace Research and Development Center (1996 a, b, c).
Shneiderman (1992) and Nielsen (1993) provide general design
guidelines and principles for designing the computer user
interface.
Two reports of the Human Capital Initiative provide a different
kind of framework: psychological research agendas. One is in the
area of aging (Science Directorate of the APA, 1993) and one in
productivity (Human Capital Initiative Coordinating Committee,
1993). The report on aging emphasizes the need to study the
oldest populations, those over 80.
1.3. ORGANIZATION OF THIS REPORT
How well do existing guidelines and design strategies capture
the needs of people with cognitive disabilities? What research
will lead to further improvements?
To answer these questions we need to be clear about four factors
in the literature, and the relationships between them:
* Distinct groups of people with cognitive disabilities: older
adults, people with learning disabilities, people with brain
injury, those with mental retardation, and so on. These
distinctions should not be dismissed as diagnostic
categories. To product managers, these terms represent
markets, whose needs vary greatly. To design teams, they
also represent distinct user groups to be recruited for
assistance with product development.
* Real-world tasks, or functions with which these different
user groups may have difficulty, such as balancing a
checkbook, keeping appointments, or remembering phone
numbers.
* Underlying cognitive factors that create those difficulties,
such as problems with working memory, executive function,
attention, or visual and spatial ability.
* Specific design changes that compensate for those cognitive
deficits. These evolve as technology evolves. New products
may relieve some cognitive burdens and introduce others.
There are many potential relationships between any two of these
factors. (For example, older adults and people with brain injury
may both have difficulty keeping appointments, but differ from
each other on other tasks.) It will be clear in this summary of
the literature that different authors' frameworks clash, both
within these factors and between them. Developing a unifying
framework - call it a "roadmap" - is beyond the scope of this
report but could be a research project. A roadmap would allow
designers to trace a path from design change back through user
task and cognitive factors to the populations served. Having a
roadmap, designers could make more principled, organized, and
coordinated design decisions.
Sections 2 through 5 of this report examine the relationships
among these factors in increasing detail. Section 2 discusses
guidelines for accessible design, identifies those that appear
to be relevant to cognitive disabilities, and notes some of the
functions or tasks to which they refer. Section 3 gives an
overview of cognitive factors and notes some of the functions or
tasks to which they may contribute. Section 4 reviews detailed
findings from the literature for some specific disabilities:
age-related cognitive disabilities, learning disabilities, brain
injury, and mental retardation. Section 5 summarizes research
that relies on very detailed analyses of tasks, cognitive
factors, and interface design changes. Section 6 concludes by
summarizing the state of cognitive disability design and
suggesting areas for further research.
----------
2. GUIDELINES & STRATEGIES
The most recent, and arguably most comprehensive, compilation of
accessibility guidelines and design strategies is that of the
Telecommunications Access Advisory Committee (TAAC, 1999). This
is a working document maintained by the Trace Research and
Development Center. It is separate from the committee's formal
report to the Access Board in 1997. These guidelines, in turn,
point to many guidelines and source documents that have come
before.
By the time design strategies show up in a cross-disability
compilation like the TAAC guidelines, they have typically been
abstracted away from particular disabilities. The document's
organization is first in terms of engineering area (input,
output, documentation, device compatibility), and second in
terms of the user's functional task (understand spoken
information, operate controls, insert disks or attach cables).
Within the Input category of the TAAC guidelines, there is
actually a subgroup of strategies specifically targeted to
cognitive disabilities. However, they are not further subdivided
into strategies relevant to aging, mental retardation, brain
injury, and so on. Other input strategies relevant to cognitive
disabilities are found in "Availability of visual information,"
"Access to moving text," and "Availability of auditory
information."
In the Output section there is no disability-specific advice,
but again strategies relevant to cognitive disabilities are
found under "Availability of visual information," "Access to
moving text," and "Availability of auditory information," as
well as "Prevention of visually-induced seizures." In the
Information, Documentation, and Training section there are many
recommendations on simplifying information presentation,
complexity, and organization. The Compatibility and Specialized
CPE section contains requirements affecting users of
augmentative and alternative communication devices.
Across the engineering categories of the TAAC guidelines, and
throughout the rest of the literature - embodied especially in
the case studies of accommodations - are four classes of
strategies:
* Redundant, user-controlled modality of information
* Streamlined, user-controlled amount and rate of information
* Procedural support
* Content organization
The first two classes of strategies benefit people with many
different disabilities, although the specific solutions may need
to be adjusted for cognitive disabilities. For example, the same
accessible design that allows people with visual or hearing
impairments to receive information in the modality of their
choice (auditory or visual) also helps people with learning or
language disabilities. The third class of strategies, procedural
support, is less well explored and documented.
The fourth class of strategies, content organization, tends not
to be included in guideline documents that focus on products and
services, except when documentation is discussed. Research
literature on learning disabilities does discuss document
content as well as reading tools. Increasing attention is being
paid to accessible organization of Web content.
The lists of detailed strategies are illustrative, not
comprehensive.
2.1. REDUNDANT, USER-CONTROLLED MODALITY OF INFORMATION
These are compensation strategies frequently used by people with
learning disabilities or language disabilities (Day and Edwards,
1996; Job Accommodation Network 1997c; Lewis, 1998; MacArthur,
1994; Raskind and Higgins, 1998; Riviere, 1996). In addition,
the ability to receive auditory information in static visual
form is useful for people who need more time to process
information (Brodin, 1992; Vanderheiden, 1997; Vanderheiden and
Vanderheiden, 1991). Specific strategies mentioned in these
sources and the TAAC guidelines (1999) include:
* Use visual examples (diagrams, icons, drawings) in addition
to text descriptions.
* Provide auditory (e.g., spoken) equivalents for all visual
information.
* Provide visual (e.g., written) equivalents for all auditory
information.
* Do both of these in a way that user may choose the
presentation on demand; for example, request that a
particular interface element be spoken aloud, instead of
requiring a screen reader.
* However, do support screen readers.
* Also support interfaces to alternative devices.
* Describe pictures; caption or transcribe audio tracks;
* provide audio description of video.
* Use multiple methods to allow users to identify and locate
controls: shape, size, texture, color, customized labels,
customized keycaps, and/or voice output to announce keys.
2.2. STREAMLINED, USER-CONTROLLED AMOUNT AND RATE OF INFORMATION
This class of strategies supports selective attention and
reduces perceptual and memory loads for people with all types of
cognitive disability. It also compensates for hemineglect in
people with brain injury. Specific strategies come from the TAAC
guidelines (1999) as well as work on learning disabilities
(e.g., Day and Edwards, 1996; Raskind and Higgins, 1998) and
brain injury (e.g., Bergman, 1991 a, b). They include:
* Provide user control of size, placement, and appearance of
display elements: high contrast, large print, numbered
* bullets, strong highlighting, placement of elements on right
or left half of display, etc.
* Support Web style sheets.
* Provide user control of pitch, volume, rate, and repetition
of auditory information.
* Support screen magnification utilities.
* Use simple screen layouts or one thing at a time
presentation.
* Use standard, simple layouts for controls.
* Layer functionality; hide less frequently used functions;
let the user customize the environment to foreground
frequently used functions. (However, the risk is that some
people may not look for "hidden" functions - out of sight,
out of mind.)
* Make the product self adjusting.
* Use orientation independent connectors and media. Use
wireless connection strategies. Ensure that connectors and
media cannot be inserted improperly.
* Provide ways in which the user may recognize, rather than be
required to recall, information.
* Avoid flash or display refresh rates that induce seizure.
* Keep all messages on the screen until the user dismisses
them.
* Provide a mechanism to speed up, slow down, or repeat
information until it is acted upon.
* Provide a non-time-dependent input method or make timing
adjustable.
* Avoid functions that require simultaneous actions to
activate or operate.
* Use a two-step "select and confirm" to reduce accidental
selections, especially for critical functions.
* Let the user set the pace of interaction with the system.
* Reduce system lag and response time.
2.3. PROCEDURAL SUPPORT
These strategies support executive functions, in particular
planning and sequencing. They reduce memory load during long
interactions with the product or system and help to counter
distractibility. Integration with calendar or reminder programs
can help to make a given telecommunication product or service
part of a well-organized, productive day. Specific strategies
are drawn from the TAAC guidelines (1999) as well as from work
on mental retardation (Brodin, 1992), brain injury (Levinson,
1995), and various cognitive disabilities (Job Accommodation
Network, 1995; 1997 a, b, d). They include:
* Structure tasks, cue sequences, and provide step-by-step
instructions.
* Provide definite feedback cues: visual, audio, and/or
tactile.
* Provide concrete rather than abstract indicators. Use
absolute reference controls rather than relative ones.
* Use goal/action structure for menu prompts.
* Support "wizards" which offer help, simplify configuration,
and assist with sequences.
* Automate complex sequences like system backup, application
launch, and user registration.
* Provide defaults and make it easy to re-establish them.
* Support integration with calendar or reminder programs.
* Provide calculation assistance, or reduce the need to
calculate.
2.4. CONTENT STRATEGIES
This class of strategies is particularly useful for people with
language or learning disabilities (Day and Edwards, 1996; Lewis,
1998; Raskind and Higgins, 1998). The literature on "content"
addresses primarily the creation and comprehension of text. This
section can certainly grow to include multimedia documents. Some
of the issues related to multimedia documents have been covered
in sections 2.1 and 2.2 above. Video captioning and Web style
sheet support are examples of those strategies.
By "content" we are also addressing not only product
documentation (TAAC, 1997, 1999; EITAAC, 1999) but also
information services such as Web pages (Nielsen, 1996). Specific
strategies cited in these sources include:
* Provide a Web site map plus path information to the current
page.
* Structure text for easy scanning; provide headings. Use
sequential numbers for numbered menus or lists.
* Keep language as simple as possible. Highlight key
information.
* Use highly descriptive words as hypertext anchors. Avoid the
"click here" syndrome.
* Search engines should support spell check.
* Searches should support query by example and similarity
search.
* Users should be able to use word prediction and grammar and
spell checkers in conjunction with all text entry.
* Users should be able to use speech recognition as an
alternative to text entry. Support speech recognition or
speech note taking as well as writing or typing, or support
interfaces to appropriate devices.
The TAAC guidelines and strategies are fairly complete. Many of
them are also measurable. A designer would know whether the
product had been significantly improved: "automate procedures,"
"use goal/action structure for menu prompts," "provide at least
one mode that does not require a response time."
But some of the strategies are a matter of degree. Without some
form of user testing or human performance modeling, a designer
would not know to what extent people with cognitive disabilities
actually benefit from overly generalized suggestions such as:
"use simple screen layouts," "keep language as simple as
possible," "reduce the number of choices."
In fact, a designer might use several strategies, even
measurable ones, yet miss the combination that makes the product
accessible to people with particular cognitive disabilities.
Verifying accessibility depends on knowing the characteristics
of distinct user groups, and assessing their performance with
the complete product. These topics are discussed in more depth
in sections 4 and 5.
----------
3. COGNITIVE ABILITIES AND DISABILITIES
When designers want to know where guidelines and strategies come
from, guideline writers often provide an overview of cognitive
deficits or of tasks that people with cognitive disabilities
find difficult. Here we will do the same.
Frameworks that others have chosen may be drawn from
neuroscience (Cole and Dehdashti, 1998), the individual
differences literature in cognitive psychology (Carroll, 1993),
or access engineering (Vanderheiden, 1998a).
Anyone interested in developing a roadmap that is strongly based
in theory should consult Carroll's work. His comprehensive
review and reanalysis of individual differences studies
demonstrate that eight broad cognitive abilities determine human
performance. Narrower abilities are classified under one of
these eight headings. To incorporate Carroll's framework into a
roadmap that can be used by designers, significant work is
required to tie his organization more clearly to functional user
tasks and to interface design (see also Dillon and Watson, 1996).
Here, we find it most expedient to list detailed findings under
the high-level headings of Cole and Dehdashti. This should not
be taken as the ultimate taxonomy and placement of some items is
quite tentative, since items gleaned from divergent sources in
the literature may refer to user tasks, underlying cognitive
abilities, or some blend of both.
An important distinction that is not captured by Cole and
Dehdashti's taxonomy is that between "fluid intelligence" and
"crystallized intelligence." Fluid intelligence is the ability
to develop techniques for solving new and unusual problems.
Crystallized intelligence is the ability to bring previously
acquired, often culturally defined, problem-solving methods to
bear on the current problem. They respond differently to several
variables, most notably aging. Fluid intelligence - flexible
innovation and the ability to learn novel things - decreases
from early adulthood onward. Crystallized intelligence -
experience - remains constant or even increases throughout most
of the working years (Hunt, 1995).
Another distinction not captured here is the difference between
"level" and "speed" factors (Carroll, 1993). The first has to do
with the ability to do a task; the second, with the ability to
do it quickly. These are worth distinguishing because they make
different predictions about user performance. For example, a
test of computer input devices showed that those that were
slowest for successful users weren't necessarily the most
difficult to master (Cress and French, 1994).
3.1. EXECUTIVE FUNCTION
This includes diverse areas such as problem solving, planning,
self-monitoring, task sequencing, prioritization, and cognitive
flexibility.
* Select and execute plans (Levinson, 1995)
Describe goals or procedures
Determine appropriate action sequences
Initiate activity
Repair plans if interrupted or postponed
Implement solution and evaluate outcome (Vanderheiden, 1998a)
Trace Research and Development Center, 1996d)
Maintain persistent effort until task done (and no longer)
* Time management (Levinson, 1995)
Understand past, future
Generate realistic schedules (Vanderheiden, 1998a)
Keep track of time (Vanderheiden, 1998a)
Perform scheduled activities within time constraints
* Self-regulation (Levinson, 1995)
Use feedback to control behavior
Inhibit inappropriate reactions
Follow rules
Understand consequences of actions, especially long-term
(Vanderheiden, 1998a)
3.2. MEMORY
This includes short-term, long-term, verbal and visual,
procedural, declarative, and implicit memory.
* Retain and recall, both short-term and long-term
(Broderbund and Alliance for Technology Access, 1997)
* Sequential - retain and recall series in order
(Vanderheiden, 1998a; Broderbund and Alliance for Technology
Access, 1997)
The following abilities have working memory and/or long-term
memory components.
* Categorize, perceive category membership
(Trace Research and Development Center, 1996d; Levine,
Horstmann, and Kirsch, 1992).
* See causal relations
(Trace Research and Development Center, 1996d).
* Understand analogical or metaphorical relations
(Levine, Horstmann, and Kirsch, 1992).
* Understand abstract concepts
(Trace Research and Development Center, 1996d).
* Generalize and apply previously learned information
(Trace Research and Development Center, 1996d).
3.3. ORIENTATION AND ATTENTION
This includes freedom from distractibility, focused attention,
and divided attention.
* Be aware of self, or self in environment; not getting lost
(Levine, Horstmann, and Kirsch, 1992; Vanderheiden, 1998a).
* Be aware of passage of events
(Levine, Horstmann, and Kirsch, 1992).
* Spatial relations: know left from right
(Levine, Horstmann, and Kirsch, 1992; Miller and Shreve,
1994).
* Compensate for hemineglect due to brain injury
(Bergman, 1991 a and b).
* Sustained attention - maintain effortful or deliberate
activity
(Miller and Shreve, 1994).
* Selective attention - attend anywhere while filtering out
irrelevant stimuli. Filter out background noise,
overwhelming input. Manage visual clutter
(Miller and Shreve, 1994; Vanderheiden, 1998a).
* Alternating attention - shift rapidly between competing
stimuli or lines of thought.
3.4 VISUAL-SPATIAL PROCESSING
This includes perception and integration of visual information
in space. The ability to construct mental pictures and use them
in problem-solving is important for mathematics (Hunt, 1995).
Some taxonomies distinguish calculation as its own category,
since, pragmatically speaking, people with cognitive
disabilities have problems with calculation and assistive
technology can help (Vanderheiden, 1998a). Mathematical tasks
can, however, be shown to include specific components such as
visualization, sequential reasoning, induction, and quantitative
reasoning (Carroll, 1993).
* Discrimination - perceive differences and similarities
(Trace Research and Development Center, 1996d)
* Organize and interpret what's perceived
(Broderbund and Alliance for Technology Access, 1997)
3.5 SENSORY-MOTOR PROCESSING
Some taxonomies do not include motor processing as a cognitive
skill, since speed of motor response may be due to physical
factors. Other taxonomies put language skill with a motor
component (such as writing or typing) underneath a "language"
heading.
Non-linguistic auditory processing is included here.
* Discrimination - perceive differences and similarities
(Trace Research and Development Center, 1996d)
* Organize and interpret what's perceived
(Broderbund and Alliance for Technology Access, 1997)
3.6. LANGUAGE
This includes expressive and receptive language, repetition,
prosody, speech rate, and fluency.
* Speak
Choose correct word and sentence structure
(Vanderheiden, 1998a; Trace Research and Development Center,
1996d).
* Listen
Understand or hear certain sounds, syllables, words
(Vanderheiden, 1998a; Trace Research and Development Center,
1996d).
* Write and type (Miller and Shreve, 1994; Vanderheiden, 1998a)
Form letters, order them (vs. mirror writing)
(World Health Organization, 1980).
Type, spell, choose correct words
(Broderbund and Alliance for Technology Access, 1997).
Organize text, develop discourse structure
(Broderbund and Alliance for Technology Access, 1997).
* Read (Miller and Shreve, 1994; Trace Research and
Development Center, 1996d)
Read individual letters, words
(Broderbund and Alliance for Technology Access, 1997)
Comprehend text, draw conclusions
(Broderbund and Alliance for Technology Access, 1997)
Understand maps, signs, symbols, pictograms, simple diagrams
or schematics
(Vanderheiden, 1998a).
3.7. EMOTIONS
This encompasses control of and expression of emotions,
detection and understanding of emotions, and frustration
tolerance. This category is noted here, but is not considered as
an issue in the remainder of this report.
* Be sensitive to others' emotional expression
* Take others' perspective
* Respond differently to situations based on context
(Levine, Horstmann and Kirsch, 1992; Vanderheiden, 1998a)
----------
4. SPECIFIC COGNITIVE DISABILITIES
Designers need to know the population they are designing for,
and who to recruit to help test or evaluate the result. Here we
summarize information found in these articles about specific
cognitive disabilities, the functional and cognitive factors
associated with them, and the design implications. This
information varies in breadth and depth. The articles on age are
the most specific about the match between design and specific
cognitive abilities. These findings should generalize to
populations with learning disabilities, brain injury, and mental
retardation in cases where the same underlying cognitive
abilities are affected.
4.1. AGE
Age is not so much a cognitive impairment as it is a
circumstance that correlates with cognitive impairments.
Differences in task performance among older adults are still
great, despite the average decline in cognitive function with
age. Part of what pulls average performance down is the
late-life onset of Alzheimer's disease and of dementia; the
percentage of adults with each of these ailments increases
sharply between ages 65 and 85 (Trace Research and Development
Center, 1996d).
A useful segment of the literature focuses on finding the
underlying cognitive mechanisms responsible for the "age"
effect, correlating task performance with those abilities, and
directing redesign to minimize differences in performance.
4.1.1. Human Capabilities
Cognitive processes that decline with age include attention,
working memory, discourse comprehension, inference formation and
interpretation, and encoding and retrieval processes. Areas that
decline less, or not at all, include semantic priming tasks,
picture recognition, implicit memory, prospective memory, and
highly practiced or expert behaviors. Explanations include
age-related slowing in learning and performing tasks, plus
failure to inhibit - attention to irrelevant detail (Park, 1992).
In the literature on mnemonic functioning, older adults most
frequently report problems remembering names. They also have
problems with immediate memory (including what one was about to
do), conversations, and recalling recent events (West, 1992).
Middle age (45-64), old age (65-74) and late old age (75+) are
distinctly different in patterns of cognitive abilities. Slowing
in response time becomes "pronounced"; by 75+ learning rate is
halved from the 20s and there are significant declines in the
ability to do two tasks at once. Fluid intelligence declines
before crystallized intelligence and both have declined by 75+
(Charness and Bosman, 1992). Adults in their 70s test 15% to 40%
lower on various measures of intelligence or cognitive function
than adults in their 20s, even when timed test-taking is removed
as a possible factor (Yesavage, Lapp, and Sheikh, 1992).
Older adults have less efficient working memory and
problem-solving skills for novel tasks. They also slow in
response time and may have an overconfidence in their ability to
handle risky situations compared with middle-age adults. The
latter is a metacognitive problem (Charness and Bosman, 1992).
Instructions that require inferring, reorganizing, or
integrating multiple sources of information place heavy demands
on older users' working memory (Morrow and Leirer, in press). A
similar pattern shows up in studies of work performance.
Cognitive ability, particularly working memory, may be the best
predictor of work performance when the worker is in
"transition," acquiring new information or learning new
procedures. "Maintenance" periods - which may extend over years
of experience - make fewer cognitive demands (Murphy, 1989; in
Park, 1992). Integration of information and complex decision
components is more difficult for older management teams
(Steufert et al., 1990; in Park, 1992). Older adults may not
show deficits in performance if the new information, however
complex, fits into already well-learned schemes.
Perceptual speed, the speed at which mental operations are
performed, is also considered fundamental to considering
age-related differences and may even contribute to differences
in working memory (Salthouse, 1985; Salthouse and Babcock, 1991;
both in Echt, Morrell, and Park, 1998).
Several studies look at how well variance in underlying
cognitive abilities explains "age" results. Age did predict
recall of automated health appointment information, even when
working memory and note-taking accuracy were taken into account
(Morrow et al., 1998a). But age did not predict comprehension
of, or memory for, printed medication information when cognitive
abilities (verbal, spatial, working memory) were taken into
account (Morrow et al., 1998b). In a study comparing older
adults' mastery of CD-ROM-based vs. printed training materials,
spatial and visual working memory best predicted success with
the CD-ROM materials. Perceptual speed best predicted
performance with the printed manual (Echt, Morrell, and Park,
1998).
4.1.2. Design implications
4.1.2.1. Pick user and task models with care.
Studies of younger adults show that matching the user interface
to the user's cognitive representation of the task increases
performance; however, the mental models must be tuned to the
given task and individual (Carroll and Reitman Olson, 1988).
Charness and Bosman (1990) outlined parameters for predicting
the performance of older adults, based on the well-received
model of Card, Moran, and Newell (1983). The field needs less
biased samples from which to derive these design parameters.
Laboratory work also needs to be extended to real-world tasks
(all citations in Charness and Bosman, 1992).
4.1.2.2. Provide streamlined, user-controlled amount and
rate of information.
Several strategies are important here. First, streamline
functionality. Because older adults have less efficient working
memory and problem-solving for novel tasks, they should benefit
more from the "training wheels" approach of limiting the
application's overall complexity (Carroll and Carrithers, 1984;
both citations from Charness and Bosman, 1992).
Provide extra time for training, for learning novel tasks, and
for performing tasks. A summary of several studies of training
techniques show no interactions with age for learning software.
However, another body of work indicates that older workers need
more time and more assistance to go through whatever training
regimen is chosen. For word-processing studies the time
difference in completing a self-paced tutorial was 1.5 to 2.5
times slower. Response time also becomes much slower with
advancing age (Charness and Bosman, 1992).
Minimize distractions. Providing extra study time doesn't fully
compensate for complex or badly organized material. Age-related
slowing is more severe for complex, ill-defined tasks, even when
older adults have unlimited time to learn. Similarly, memory
training has the potential of improving basic, general cognitive
processes, but older adults tend to be sensitive to context - or
to the wrong aspects of context - and may not generalize the
training (Park, 1992; Yesavage, Lapp, and Sheikh, 1992).
4.1.2.3. Use prompts for procedures and support
decision-making.
In particular, expect and support reliance on external memory
aids. In studies of automated appointment reminders, enforced
message repetition reduced age differences in recall. When
repetition was made optional, older patients did take advantage
of it. (This indicates some metacognitive skills at work.) They
paid enough attention to take accurate notes but not enough to
recall as much as younger patients (Morrow et al., 1998a; Morrow
et al., 1995). External strategies - lists, calendars, visual
cues, notes - are older adults' most common type of memory aid
in everyday situations. They are preferred to internal memory
strategies (West, 1992). A simple accommodation is the use of a
phone with memory buttons for older adults who have difficulty
remembering numbers. Pictures can be added to the memory buttons
for those who have trouble with names or codes (Mann, 1996).
4.1.2.4. Support content strategies.
Bear in mind that training format matters less than careful
design of materials. One study evaluating four types of training
found that ATM accuracy and transaction times were best for an
online tutorial group, intermediate for detailed text and
pictorial guide groups, and worst for a description-only group.
However, even with the tutorial, older adults were only 60%
correct in completing all the components of each transaction
(Rogers et al.; in Rogers and Fisk, 1997). However, a study
comparing older adults' mastery of CD-ROM-based vs. printed
computer training materials found no performance difference due
to type of material. In this case, the printed manual was
comparable to the CD-ROM in content except for animation, and
the manual format was designed with older adults in mind: large
sans serif print, concise content, bolded key terms, and
easy-to-see colors (Echt, Morrell, and Park, 1998). Again,
pictures are no panacea; those that require more inferences
penalize older adults (Morrow et al., 1998b).
Require fewer inferences, or help people to make them. In
studies of medication information, iconic medication timelines
were added to well-designed text instructions. When the icons
were integrated (with more explicit information about time and
dose, thereby requiring fewer inferences), both younger and
older adults comprehended them better than text alone.
Nonintegrated icons, which required more inferences, penalized
older adults. Note that this means that including illustrations
in documentation is not automatically beneficial (Morrow et al.,
1998b; compare the TAAC guidelines and strategies, 1999). In
studies of wayfinding, it was easier for older adults to learn
their way around unfamiliar environments when helped to
integrate different views or perspectives into a mental model of
the entire space (West, 1992).
Re-use familiar, well-learned organizational schemes. In studies
of spatial memory, older adults using consistent, organized
arrays for objects find them as easily as younger adults. Older
adults benefit from familiar environments because of self-paced
knowledge acquisition, distributed practice, and overlearning.
(West, 1992)
Experiments on medication instructions showed that older and
younger adults actually share an organizing scheme for such
information. (This is culturally shared, "crystallized"
intelligence, as described by Hunt, 1995. It is less likely to
decline with age.) Written instructions using this common scheme
increased recall 13 - 20% overall. Additionally, a list format
reduced age differences in comprehension time and particularly
benefited the oldest (over 70 years) participants (Morrow and
Leirer, in press).
4.2. LEARNING DISABILITIES AND LANGUAGE IMPAIRMENTS
Learning disability (LD) is a generic term covering multiple
functional impairments. Because so many people with LD have
problems with written and spoken language (Raskind and Higgins,
1998; Reid et al., 1991), accessibility guidelines often include
people with language impairments in the same category as those
with LD.
4.2.1. Human Capabilities
Learning disabilities are marked by problems in the "acquisition
and use of listening, speaking, reading, writing, reasoning, or
mathematical abilities" (Hammill et al., 1987). Individuals with
LD will have significant difficulties in one or more of these
areas but also relative strengths in others. By comparison,
individuals with mental retardation will have a flatter, lower,
"strength" profile (Shaw et al., 1995).
The most commonly reported difficulties are in reading and
writing, but it's likely that oral language and mathematical
disabilities are underreported (Johnson and Blalock, 1987).
Working memory seems to be implicated in problems with
mathematical reasoning, since that disability becomes more
apparent as cognitive load increases. Another study indicates
that LD readers' working memory deficits are greater than those
of nondisabled readers (Reid et al., 1991). Crystallized
knowledge - accumulated experience - is also affected. LD
students with reading problems frequently have slow lexical
access, which decreases their attention and comprehension. As
they grow older, this leads to cumulative deficits in knowledge
and language acquisition (Snider and Tarver, 1987, in Reid et
al., 1991).
Educators evaluating people with LD should be able to identify
information processing difficulties that explain the functional
impairments: short- or long-term memory, strategic learning,
automatization of skills and strategies, or executive control of
strategies. Further limitations in sensory abilities, physical
abilities, or psychosocial skills may occur with LD or may help
rule it out in favor of another explanation (Shaw et al., 1995).
4.2.2. Design Implications
4.2.2.1. Provide redundant, user-controlled modality of
information.
The same accessible design that allows people with visual or
hearing impairments to receive information in the modality of
their choice (auditory or visual) also benefits people with
learning or language disabilities (Day and Edwards, 1996; Job
Accommodation Network 1997c; Lewis, 1998; MacArthur, 1994;
Raskind and Higgins, 1998; Riviere, 1996). People who have
problems with written text can hear it spoken, and vice versa.
In one typical study, people with dyslexia who were able to scan
written materials into an optical character recognition device
with speech synthesis increased their reading rate and
comprehension (Elkind, Black, and Murray, 1996, in Raskind and
Higgins, 1998). In another, adding speech to text had a
rehabilitative effect: it doubled the rate at which students
acquired decoding (reading) skills (Wise and Olson, 1994, in
Lewis, 1998).
4.2.2.2. Provide streamlined, user-controlled amount and
rate of information.
Features particularly useful to people with LD are the ability
to speed up, slow down, or repeat information, particularly
auditory information.
Related to this is the ability to focus attention and minimize
distraction by having the product display information in large
print or high contrast, and by highlighting text by the word,
phrase, or sentence as it is read aloud (Job Accommodation
Network, 1997c). Distraction is also a potential problem with
multimedia enhancements to static text. Hypermedia in talking
books is intended to provide pronunciation aids, illustrations,
and other reading aids. Its secondary benefit is to promote
engagement with the text (Lewis, 1998; MacArthur, 1994). But
animation and other "hot" visual effects can be distracting.
Swanson (1989, cited in Lewis, 1998) argues that individuals
with learning disabilities are typically "inefficient rather
than passive" learners. If so, animation will draw their
attention away from, rather than engaging their attention to,
the task.
4.2.2.3. Prompt procedures and support decision-making - but
don't expect everyone to use very structured tools.
People with learning disabilities use organizing devices ranging
from "freeform databases" (simple electronic lists), to watches
with alarms, to voice activated day planners with voice input
technology (Job Accommodation Network, 1997c; Riviere, 1996).
From this range of devices one can begin to infer the
variability in users' needs. Some need text input and output,
and some need spoken language. Some benefit from structured
tools, while others need to capture information quickly without
having to worry about how to enter it into the system.
Task specific planning and decision aids are also useful. Since
so much of LD accommodation focuses on language, the most
commonly cited planning and decision aids are outliners, idea
generation and capture programs, and other writing tools.
Students with LD typically have problems with the planning
activities associated with writing: setting goals, generating
content through memory search and information gathering, and
organizing material carefully (Flower and Hayes, 1981, in
MacArthur, 1994).
Talking calculators and other mathematical tools are also
included in the "procedural support" category.
4.2.2.4. Support content strategies.
All the strategies listed in section 2.4 apply when designing
for people with learning disabilities. These include the use of
well-structured text, aids to text entry, and support for speech
recognition and speech notetaking. The speech technologies are
especially appropriate for portable, networked
telecommunications devices. Voice dialing is an alternative to
number entry. Telephone recording (as with an answering machine)
lets people review the content of a phone call at their own
pace. Speech notetaking is an alternative to written notes (Job
Accommodation Network, 1997d).
4.3. TRAUMATIC BRAIN INJURY
People whose cognitive functioning has been affected by closed
or open head injury or by stroke are said to have traumatic
brain injury (TBI). People with TBI vary greatly in severity and
type of cognitive disability. The literature on "cognitive
prostheses" - computer systems that support these people in
resuming activities of daily living such as managing household
affairs - emphasizes highly customized software with few
functions (Bergman, 1991a, b; Bergman and Kemmerer, 1991;
Bergman, 1998; Chute et al., 1988; Cole and Dehdashti, 1998).
However, it appears that the people willing to spend time and
money on a cognitive orthotic are those whose disability is so
severe that they cannot use off-the shelf products.
4.3.1. Human Capabilities
Brain injuries often result in selective, rather than global,
memory deficits. For example, amnesic patients can acquire a
variety of motor, cognitive, and perceptual skills in a nearly
normal fashion but not remember the learning episodes (Glisky,
1992). Cognitive dimensions of profound disability often contain
small pockets of ability, which are made visible during detailed
software development of assistive technology (Cole & Dehdashti,
1998).
Case studies illustrate how cognitive disabilities may cluster
and vary from individual to individual. Here are a few examples:
* Difficulty and strain in attending to items on one side of
the visual field (hemineglect); problems with short-term
memory, sequencing, and executive functions (Bergman, 1991a).
* Problems with memory, oral communication, processing speed,
and concentration (Bergman, 1998). n Amnesia; also problems
with prospective memory, attention, concentration,
visual-spatial processing, and executive functions (Cole and
Dehdashti, 1998).
* Expressive aphasia (communication limited to head
movements); also memory limits and visual, spatial, or motor
problems with computer cursor control (Chute et al., 1998).
* Moving information from short-term to long-term memory: an
inability to remember any new information after 30 minutes
(Cole and Dehdashti, 1998).
* Short-term memory loss, auditory discrimination problems,
and visual difficulties with computer screen flicker and
glare (Job Accommodation Network, 1997a).
With appropriate accommodations and assistive technology, people
who had spent years attempting to use computers and other
communication aids have been able to live and work more
independently. They were able to manage their own schedules,
create and read text documents, balance their checkbooks, and
pay bills. In one mild case, the remedy was as simple as
providing a distinctive ringer on the phone and an anti-glare
screen on the computer (Job Accommodation Network, 1997a).
In the literature surveyed, only the work of Glisky and
colleagues (Glisky, 1992; Glisky, Schachter, & Tulving, 1986)
measures brain injured participants' underlying cognitive
abilities and correlates them with task performance. People with
amnesia have lower scores on memory tests - for example, on
delayed tests of logical memory and visual reproduction.
However, people with mild or moderate amnesia, given an
appropriate training environment, may equal nondisabled people
in learning and performance of simple, structured tasks such as
data entry.
On the average, amnesic patients learning basic computer
programming and file manipulation started out with the same
knowledge as non-disabled participants, eventually made few
errors, and retained information over one or more months.
However, they took much longer to reach criterion. They did less
within-session learning and more between-session forgetting.
They also had difficulty answering general or open-ended
questions about what they had learned (Glisky, Schachter, &
Tulving, 1986). Amnesic patients learning data entry, a simpler
task, could demonstrate knowledge they had gained even if they
could not describe it. Their rate of gain in task speed was the
same as that of non-disabled participants: 50% during the first
training round, 15% during the second (Glisky, 1992).
4.3.2. Design Implications
4.3.2.1. Provide streamlined, user-controlled amount and
rate of information.
Most importantly, provide a mode with minimum functionality.
Eliminate or hide what isn't essential. A Business Week cover
story argues the benefits of streamlining consumer products
(Nussbaum and Neff, 1991). The cognitive aids described here go
much further (Bergman, 1991a, b; Bergman and Kemmerer, 1991;
Bergman, 1998; Cole and Dehdashti, 1998).
The design approach reads like a stringent version of the TAAC
strategies (1999). Applications each had very few functions,
compared to off-the-shelf software. (For example, the text
processor described by Bergman, 1991b, had two functions and was
upgraded to three.) Error messages were concrete. Important
functions were moved to labeled, unshifted keys. Hemineglect was
accommodated, for example, by shifting screen objects to one
side of the display. Sequences were simplified, prompted, or
eliminated. Redundant, multisensory cues were added. Typical
components in both systems included a text processor, a
check-writing program, a daily schedule, a paint program, and a
remote control application that enabled the user to work with a
therapist on line. In one case a scheduler with a pager was
customized for a physician who sent himself appointment
information and other timed reminders (Cole and Dehdashti, 1998).
The telecommunications equivalent of such a system might be
something like the hypothetical "Companion" described by
Vanderheiden (1992), a simple wireless phone with voice output
and speech recognition, problem-solving aids, and reminder
function.
Also, support radical customization, either by the user or by
someone working with the user. Both Bergman and Cole and
Dehdashti report adding, deleting, or modifying entire
components of the product for each user. Cole and Dehdashti note
that customization was instance-specific as well: cognitive
chunks in different parts of the software needed to be different
sizes. Iterative, participatory design sessions were
particularly common with early users of their system. In later
versions they succeeded in doing mass customization more
quickly.
4.3.2.2. Provide self-paced training and consider an
adaptive trainer.
Adaptive trainers are discussed further in section 5.3. Briefly,
they block certain errors, diagnose others, suggest effective
responses, and fade into the background as users' skills
increase. Effective computer training systems for amnesic
patients (Glisky, Schachter, & Tulving, 1986; Glisky, 1992)
acted like adaptive trainers. They provided vanishing cues,
evaluated responses, and occasionally offered more direct
prompts. The systems were self-paced. It may also be important
that users had the opportunity to learn the knowledge
completely, or even "overlearn" it.
4.3.2.3. Use prompts for procedures and support
decision-making.
People with brain injury and those with learning disabilities
have many of the same needs in this area. People with brain
injury may be more likely to need support with executive
functions such as planning and scheduling. An interesting device
that meets this need is PEAT, a hand-held electronic calendar
and address book that has built-in telephone, fax, and Internet
capabilities (Levinson, 1997). It generates daily plans, checks
with the user about how activities are progressing, and
reschedules activities in order of importance if the user is
falling behind schedule. The planner is based on a simulation of
the brain's own planning functions.
4.4. MENTAL RETARDATION
Mental retardation (MR) appears before adulthood. It is
characterized by "significantly subaverage intellectual
functioning" with related limitations in two or more of the
following areas: communication, self-care, home living, social
skills, community use, self-direction, health and safety,
functional academics, leisure, or work (American Association for
Mental Retardation, 1999). Mental retardation is characterized
by limitation in both intellectual and adaptive skills.
4.4.1. Human Capabilities
People who are mildly retarded (80-85% of the population with
MR) have an IQ between 55 and 69. They achieve a 4th through 7th
grade education and function well in the community, holding down
semi-skilled and unskilled jobs (Trace Research and Development
Center, 1996d).
People with MR have working memory deficits. Perceiving,
processing, and storing information require greater effort, and
take more time. Specifically, people with mental retardation
have problems with sensory discrimination. Also, since people
with MR have difficulty thinking in abstract terms, concrete
operations and a concrete environment are essential for their
accommodation (Brodin, 1992)
Note how the profile of people with MR is different from that of
people with learning disabilities or brain injury. In the latter
cases there tend to be specific deficits but also relative
strengths in many other functional areas. We would expect that
some of the tools used by people with learning disabilities
would need to be adapted for use by people with mental
retardation. For example, a program that speaks written text
would need to be much simpler than a typical computer-based
screen reader.
The performance of people with mental retardation is not just a
slower, scaled-down version of that of nondisabled adults, nor
is it equivalent to that of nondisabled children. This is
particularly true for tasks that have both cognitive and motor
components. A person with mental retardation may be physically
more capable of doing the task than a young person of the
equivalent mental age, but may have greater cognitive
difficulties.
In a study comparing learning of 5 input devices, adults,
children with MR, and normally developing children had different
patterns of device mastery and task speed. The touchscreen (the
fastest device overall) was significantly slower for children
with MR, possibly because they tended to separate the
simultaneous pickup and drag of targets into separate actions.
Normally developing children mastered all devices after
relatively brief training sessions; children with MR did not
master the devices as easily, even with training, and had
particular problems with the trackball and locking trackball
(Cress & French, 1994).
4.4.2. Design Implications
4.4.2.1. Provide streamlined, user-controlled amount and
rate of information.
To do this, provide a mode with minimum functionality. Eliminate
or hide what isn't essential. The "Companion" hypothesized by
Vanderheiden and mentioned in the section on brain injury was
actually created with mental retardation in mind. In terms of
other strategies, user-defined pacing and adaptive training are
likely to be useful, but there is no direct evidence for that in
these articles. Minimizing distractions is another promising
strategy, but again there is no evidence here specific to MR.
4.4.2.2. Provide redundant, user-controlled modality of
information.
Providing that operation is simple, people with mental
retardation benefit from having text information spoken aloud.
They would also benefit from having status tones translated into
something more meaningful, such as visual indication of call
status (Kaplan, DeWitt, and Steyaert, 1992). In several studies
of moderately retarded adults and children, the introduction of
still picture phones increased callers' independent use of
telephones. Communication was more effective and user
satisfaction and self-confidence were greater, perhaps because
these devices make visual and auditory information available
simultaneously (Brodin and Magnusson, 1992 a, b; Brodin, 1994).
Videophones with Pictogram monitors and document cameras were
more complex and presented usability problems (Brodin, 1994).
4.4.2.3. Prompt procedures and support decision-making.
Vanderheiden (1992, 1998b) recommends such aids. The Job
Accommodation Network (1997a) gives a low-tech example: a
greenhouse worker carrying a tape recorder with reminders to
stay on task and indicators of break time. Again, talking
calculators, automatic checkbooks, and other mathematical tools
are included in the "procedural support" category (Vanderheiden,
1992). Orientation aids are important for those who tend to
wander or who may need to be located by emergency services
(Vanderheiden, 1992, 1998b); this could equally well apply to
older adults with dementia or Alzheimer's.
4.4.2.4. Support content strategies.
There is some design guidance on using simple language, if we
take as a starting point that people with moderate mental
retardation achieve a 4th through 7th grade education.
----------
5. TOWARDS BETTER GUIDELINES AND STRATEGIES : CLOSING THE GAP
Great improvements in product design can be made by providing
access where none existed before. Provide information in
redundant modalities; remove time-dependent controls; eliminate
sequences. Each of these strategies makes it possible for people
with disabilities to use products they could never use before.
But if designers take as their goal the EITAAC (1999) benchmark
that people with disabilities should be able to "perform the
same tasks, access the same information, with the same
approximate ease and in the same approximate time and at the
same cost," then a finer analysis of user ability and task
performance is needed.
Individual differences in task performance, even among people
without disabilities, are massive. The ratio between slowest and
fastest computer task times can be 20:1. Even the ratio between
people at the 25th and 75th percentiles can be 2:1 to 4:1. For
word processing and information search, the greatest source of
differences is time in making and recovering from errors. In
programming, mental representation of the problem and the system
also has a significant effect (Egan, 1988).
Egan demonstrates that careful attention to these individual
differences can guide interface design, resulting in the
elimination of age, aptitude, and experience disadvantages. His
goal is to aid the people having the most difficulty, without
penalizing those with better performance. His methods work for
the cognitive differences underlying "age," and they should work
equally well for differences underlying other cognitive
disabilities.
5.1. CORRELATIVE WORK: ASSAY, ISOLATE, ACCOMMODATE
The methodology for closing the gap is elucidated by Egan and
Gomez in studies of text editing performance (1985; Egan, 1988).
First, assay individual differences. Find out which ones
correlate with performance on the chosen task. Many plausible
factors may be irrelevant. Egan and Gomez found that only age
and spatial memory mattered for the text editors they studied;
education, typing speed, verbal aptitude, job experience,
associative memory, and logical reasoning had no effect on
performance.
Second, isolate task components. Do a task analysis and
determine which components individual differences affect. This
is admittedly an art. Egan and Gomez verified their analysis by
creating new tasks with the same components and obtaining the
same pattern of correlations, but this additional test is
impractical for design teams.
Third, accommodate the differences by redesigning the interface
to minimize performance differences. Measure user performance
again. Egan and Gomez compared a line editor to a newer display
editor. The newer design simplified command syntax, reducing age
differences in performance, but the changes related to spatial
memory ability were mixed (and cancelled each other out).
5.2. USER PROTOTYPES
Egan (1988) outlined four ways in which user interfaces could
accommodate individual differences. These approaches range from
user interface focused to training focused:
* Interface robustness: the improved mass market design of
products used casually by large numbers of people. This is
the approach discussed in section 5.1 above.
* User prototypes: tailoring the interface to meet the needs
of a few broad classes of people.
* Adaptive trainer systems: supporting novice performance by
prohibiting certain errors, diagnosing others, and prompting
effective responses. Appropriate to settings where people
need to learn a moderate amount to become productive.
* Automated mastery learning: providing customized intensive
training. Most appropriate where people need to master a
great deal of material to a high level of proficiency.
In practice, universal design uses both "interface robustness"
and "user prototypes." Examples of the latter include providing
interfaces in different languages, or creating a basic mode that
presents much less functionality than the full product. The EZ
Access strategies (Law and Vanderheiden, 1998; Vanderheiden,
1997; Vanderheiden, Law, and Kelso, 1998) could also be placed
in the user-prototype category.
5.3. ADAPTIVE TRAINERS AND AUTOMATED MASTERY LEARNING
Adaptive trainer systems would seem to be ideal for people with
cognitive disabilities. Glisky (1992; Glisky, Schacter, and
Tulving, 1986) used such a self-paced system to train people
with amnesia on computers, using cues that gradually vanished
when no longer needed. Older adults may also benefit from fading
cues that help them generalize to full, unaided use of a system
(West, 1989). The concept is also known as "scaffolding."
Scaffolding is part of a universal design approach to curriculum
which includes summarizing main ideas, providing scaffolds for
learning and generalization, building fluency through practice,
and assessing background knowledge (Rose, 1988).
Adaptive trainer systems relieve memory burdens by providing
assistance with novel sequences and prompting data entry (TAAC,
1999).
As when designing more robust, universal interfaces, careful
task analysis is essential. To design a trainer system, it is
crucial to know how errors cluster, what their causes are, and
what will promote transfer from the trainer system to the full
system (Egan, 1988).
The line between trainer system and interface enhancement blurs
in the case of "wizards," which remain available to users even
after initial training. Wizards are included in today's mass
market products more frequently than Egan might have anticipated
in 1988.
Automated mastery learning environments, although they are
effective cognitive aids, are expensive to develop and require
detailed user modeling. The self-paced math and programming
tutors developed by Anderson and colleagues (1995) are excellent
examples. The cognitive benefits of using the tutors were
significant: in the best case, nondisabled students cut learning
time by one- to two-thirds and scored significantly higher on
post-tests. The success of that tutor was largely due to the
sophistication of the user model, which predicted
moment-by-moment what knowledge each user had or had not
acquired. However, Anderson et al.'s other principles of tutor
design can be taken from that report and added to accessibility
guidelines and strategies. Some of them are already familiar:
* Provide instruction in the problem-solving context - but
between problems, not during them. Otherwise,
problem-solving is interfered with. (This appears to be a
case of interference with working memory and perhaps
executive function.)
* Promote an abstract understanding of the problem-solving
knowledge. Help students generalize principles from concrete
examples.
* Minimize working memory load. Minimize irrelevant
information and teach new components only when others have
been relatively well mastered.
* Provide immediate feedback on errors. This is best for
reducing task time, most likely by reducing time spent in
error (see also Egan, 1988). Simply flagging errors or
providing feedback only on request is less successful.
* Facilitate successive approximations to the target skill.
Let the tutor fade gradually into the background with
repeated practice.
----------
6. RECOMMENDATIONS FOR FUTURE RESEARCH
Functional guidelines already exist, as do a variety of
practical strategies for making better products for people with
cognitive disabilities. In the belief that product-specific
strategies will continue to be improved by design experience, we
begin this section with the most concrete areas for research.
6.1. REFERENCE DESIGNS
Designers often work from examples. A research project that
creates one or more examples serves several important functions.
First, it demonstrates the feasibility of universally designing
appealing products that are also usable by people with cognitive
disabilities. This is especially important given the stigma
associated with cognitive disabilities. Second, the examples can
be publicized and specific design solutions can begin to find
their way into commercial products. Third, working, user-tested
designs create more data from which detailed strategies can be
derived.
The Trace Research and Development Center has created just such
a "reference design" for an accessible wireless phone (1999).
Features in the reference design that are most relevant for
cognitive disabilities are:
* An EZ button that allows one to have the label for any key
read aloud, as well as the contents of the display and all
menus and features of the phone.
* An infrared port for wireless connection to assistive
technologies.
* A "one button feature" that allows the phone to be
programmed so that it will automatically dial only one
number (or a small list of numbers) when any keypad button
is pushed. An optional cover plate to create a true "one
button phone" can be added.
This is a good start for basic telephony functions. The
reference design doesn't address the complexity of the menus - a
service-dependent issue, rather than a hardware issue, that is
nonetheless an important one for users. Nor does it explicitly
address the degrees of customization that might be available
between "full functionality" and "one button" operation.
There are certainly other potential reference designs that could
be used to explore those issues:
* Phone plus Personal Digital Assistant (PDA). Wireless phones
are now being manufactured that incorporate a larger
touchscreen with stylus. In addition to hardware
accessibility and usability issues (see Cress and French,
1994), the phone-plus-PDA also provides software that is
important to people with cognitive disabilities. How
accessible and usable is the calendar/reminder program? The
address book? The expense tracker? The Web browser? The
email program? How would useful configurations of this
device vary between someone with learning disabilities and
someone with mental retardation? Are there a few default
customizations that could easily be downloaded from the
manufacturer's or service provider's Web site?
* Phone-plus-PDA combined with desktop computer. How can
desktop-PDA integration make both systems easier to use for
people with cognitive disabilities?
* Web style sheets. Service providers sending Web content to
restricted displays (televisions, PDAs) filter and reformat
it to fit. The content can become quite streamlined. How
does this relate to features of content design that help
people with cognitive disabilities better navigate and use
the Web? Does it make sense to have specific style sheets
for various cognitive disabilities, just as there are
several large print, high contrast schemes for people with
low vision? And how might this work generalize to talking
books and to instructional CDs? (See Hendrix and Birkmire,
1998; Nielsen, 1996; World Wide Web Consortium, 1998.)
6.2. SPECIFIC DESIGN ISSUES
6.2.1. Layered or Restricted Functionality
Between full functionality and one-button operation lie
intermediate levels of cognitive difficulty. In the training
literature this is called a "training wheels" interface (Carroll
and Carrithers, 1984; in Charness and Bosman, 1992). It is
possible to measure how effective these interfaces are, both in
and of themselves, and as a way to block typical errors and
promote learning of the full product (Egan, 1988). In mass
market products, layered functionality shows up as "short menus"
and feature-hiding panels. How effective have those
implementations been, particularly for people with cognitive
disabilities? Are there principled methods for determining how
to layer or prune functionality? How might this be demonstrated
in the effective design of a phone-plus-PDA device?
6.2.2. Training, Procedural Support, and Problem-solving
The adaptive training and tutoring systems described in this
report (Anderson et al., 1995; Glisky, Schacter, and Tulving,
1986; Glisky, 1992) were effective but time-consuming to
develop. Yet mass market computer interfaces now have wizards
and intelligent help systems that watch the user's behavior and
offer support. How well do these interfaces work for people with
cognitive disabilities? How can they be improved? How can they
be brought into the world of small but networked
telecommunications devices?
In the area of problem-solving, we have the example of PEAT
(Levinson, 1997), a problem-solving device that specializes in
planning and scheduling. There are other problem-solving aids
that could be redesigned for people with cognitive disabilities
and adapted to portable telecommunications devices. For example,
people with cognitive disabilities need orientation and
wayfinding (Vanderheiden, 1998b). One can begin to see the
components of a better portable tool. First, on the Web there
are free mapping and route-planning services, but the directions
may be difficult to follow for people with sequencing and
visualization impairments. Second, the "Atlas Speaks" product by
Arkenstone takes pre-planned route information and downloads it
into a portable device, in text or audio format. Finally,
wireless phones will provide positioning information. If the
positioning information is sufficiently accurate, it may be
possible for users not only to play back pre-planned directions,
but also to find out where they are, determine whether they are
off track, and request new directions from a network service.
Such a device could also receive precise local information from
Talking Signsr (Crandall, Bentzen, and Myers, 1998) in
environments where those are available.
6.3. USER PROFILES AND QUICK TESTS
Designers have less understand of cognitive disabilities than
sensory or mobility impairments. In our experience, designers
without access engineering background tend to think of cognitive
disabilities as something like mental retardation, a broad and
general intellectual impairment. They do not yet understand the
specific deficits resulting from aging, learning disability, or
brain injury. Nor, more importantly, do they yet understand the
mapping between those specific deficits and equally specific
design solutions.
Designers need more concrete pictures of people with cognitive
disabilities. These pictures, or "user profiles," help designers
create usage scenarios for a product (Nielsen, 1993;
Shneiderman, 1992). For example: "Jane, who has a specific
learning disability, gets a reminder from her electronic
appointment calendar and then sets up a conference call." User
profiles and usage scenarios help designers before systematic
user testing is possible, in the early stages of product
definition. They are refined throughout the project. They serve
as test cases: "Would this feature we are thinking about really
help Jane?"
When these user profiles are developed, people with cognitive
disabilities should be recruited as active participants in the
process (Doe and Whyte, 1995).
It might even be possible to create "quick tests," rough
simulations of what it is like to use products when one has a
given cognitive disability. The goal of a quick test is not to
be a precise simulation of human performance but to give
designers a sense of the user experience. They are useful when
formal testing with real users is not possible.
6.4. USER MODELS AND HUMAN PERFORMANCE CHARACTERISTICS
Usability testing is only one method of evaluating human
performance with a product. Human factors engineers can create
user models, which are predictive simulations of a person's
performance with an interface.
How long does it take to read the display? To decide which key
to press? To press it? To evaluate the result? If one interface
requires more keypresses, but another requires an extra
decision, which is the better design - and for whom?
User models are based on estimates of human perception,
cognitive processes, and motor behavior. These estimates can and
should be extended to include people with disabilities. Charness
and Bosman (1990) combined the well-regarded methods of Card,
Moran, and Newell (1983) with performance data from the aging
literature to arrive at parameters for predicting the
performance of 57.older adults. It is important to include
adults over 75, since their cognitive capabilities are
distinctly different from those of the "young-old" between 65
and 75 (all citations in Charness and Bosman, 1992).
Given the time and effort that user modeling currently requires,
it may be na=8Bve to think it will significantly reduce the need
for usability testing (as suggested by Dillon and Watson, 1996).
However, the field of usability engineering needs design tools
that cover people with disabilities as well as those without.
6.5. CORRELATING DESIGN WITH COGNITIVE ABILITIES
Throughout this report we have highlighted research that ties
specific design issues to equally specific human cognitive
capabilities. This correlative research (exemplified by the work
of Egan, Glisky, Morrow, and various researchers on cognitive
aging) has two important benefits.
First, it helps to refine existing design strategies. For
instance, because of the work of Morrow and colleagues on icon
design (1998b), designers know more about implementing the TAAC
strategy of including illustrations in documents (1999).
Second, correlative research is a principled way of tying
accessible design to universal design. It recognizes the
underlying cognitive ability (e.g., working memory). It also
acknowledges the wide variation in that ability within
populations as well as between them (Egan, 1988).
In accordance with the EITAAC approach (1999), priority should
be given to research on closing the gap in performance between
people with disabilities and those without. This will also help
equalize performance within nondisabled populations.
It's also important to include participants with disabilities
who are less educated, wealthy, and independent than those
typically recruited for studies. A rare example is the work of
Craik, Byrd, & Swanson (1987, in Park, 1992). They compared
recall performance of low-income, inactive elderly people with
that of low-income active elderly, upper income active elderly,
and young active adults. More structured recall cues helped to
close the gap: the most disadvantaged, worst performing group
made the largest improvements in recall. More attention also
needs to be paid to older aging populations, those over 75
(Charness and Bosman, 1992; Echt, Morrell, and Park, 1998;
Science Directorate of the APA, 1993).
The design topics of this correlative research will, of course,
change as technology changes. The text editor improvements
proposed by Egan and Gomez (1985) are commonplace today.
Researchers in this area need to choose design topics that have
the greatest possible impact given technology trends and product
availability.
6.6. THE ROADMAP
Finally, there is the roadmap discussed in section 1.3. Without
this unifying framework, it is difficult to be clear about the
relationships between these four factors in the literature:
* Distinct groups of people with cognitive disabilities.
* Real-world tasks or functions with which these various user
groups have difficulty.
* Underlying cognitive factors creating those difficulties.
Specific design changes that compensate for the cognitive
deficits and improve task performance. Correlative studies
(section 6.5) and reference designs (section 6.1) contribute to
the roadmap, but need to be tied to a better theoretical
framework (such as Carroll, 1993). User profiles (section 6.3)
and underlying demographics are also a part of the roadmap, and
are useful to marketers who need to understand the business
implications of serving these markets.
----------
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APPENDIX 2: ANOTATED BIBLIOGRAPHY
There are 111 documents in the bibliography. The documents can be
grouped as follows: n 23 discuss characteristics of people with
cognitive
12 disabilities or more general human cognitive capabilities. n
55 cover products currently used by people with cognitive
disabilities or evaluate particular interfaces as a function of
cognitive ability. n 5 hypothesize uses of certain technologies.
28 contain design guidelines (including cross- disability
guidelines) or other organizing frameworks. More information was
found on technology for people with learning disabilities than
for people with aging- related cognitive disabilities. Technology
for people with traumatic brain injury or mental retardation is
even less frequently documented. Also, there is significantly
more information about computers than about telephones or other
telecommunications equipment.
[Rest of bibliography omitted because of size -- over 400K]
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End of Document
Received on Friday, 12 May 2000 01:09:43 UTC