Accessible Design of Consumer Products

Guidelines for the Design of Consumer Products to Increase Their Accessibility to People with Disabilties or Who Are Aging

Working Draft 1.7 -- 1992

Compiled for The AD HOC Industry-Consumer-Researcher Work Group of the Consumer Product Design Guidelines Project by Gregg C. Vanderheiden and Katherine R. Vanderheiden

Support for the preparation and dissemination of this document has been provided by the National Institute of Disability and Rehabilitation Research (NIDRR), US Dept. of Education\ under grant # G00850036 and by the Assistive Devices Division, Consumer Electronics Group, Electronic Industries Association.

This document is being sent out specifically for comment and suggested revisions from industry, consumers and researchers. Please feel free to mark up, comment, improve or take exception to the document in any way you see fit and send your comments to us. All responses and comments can be kept in strict confidence, allowing you to comment freely as individuals or organizations with anonymity. Your input is important to this process. Send comments to

CONSUMER PRODUCTS GUIDELINES PROJECT
C/O Trace R & D Center
S-151 Waisman Center
University of Wisconsin - Madison
1500 Highland Ave.
Madison, WI 53705
Attn: Gregg C. Vanderheiden Ph.D.

NOTE: To facilitate this document's review and use, you are free to duplicate and disseminate it freely. You may also excerpt ideas and materials from it freely. However, please send us a copy of your work as well for our information and interest.

Some of the charts and concepts in this document are taken from other authors and publications. These are so marked, and separate permission must be sought directly from those authors or publications before use (apart from copying this whole document).

The opinions expressed in this document do not necessarily reflect the opinions of NIDRR, the Assistive Devices Division of EIA or the individuals listed as contributors. Nor do all of the opinions necessarily represent the opinion of the compilers, since this document represents a compendium of input from many sources.

ABOUT THE PROJECT WORK GROUP

The AD HOC Industry-Consumer-Researcher Work Group is an open group composed of those individuals interested in more accessible consumer product design and contributing to the development and refinement of these guidelines. The work group is headquartered at the Trace R & D Center at the University of Wisconsin - Madison. Anyone can join by reviewing, and submitting comments to correct, elaborate or extend these guidelines. Communications of the ad hoc work group are carried out by mail to facilitate participation by industry and consumer representatives who would not otherwise be able to attend particular meetings or conferences. To participate in the work group, simply send your comments, ideas, corrections or extensions to the guidelines to the address on the cover of this report.

ACKNOWLEDGEMENTS

Many individuals contributed to the development of these guidelines, both formally and informally, including students who participated in an Industrial Engineering Department Seminar on Design and Human Disability and Aging at the University of Wisconsin - Madison. Among the professionals, consumers, industry representatives and students contributing to these guidelines are:

Karen Athens
Keith Bednar
Jane Berliss
Lori Beth
Mary Ann Bird
Peter Borden
Eli Chu
Suruedee Chumroum
Raúl Colón
Cynthia Cress
Joanne Deda
Thomas Findley
Jackie Finley
Clint Gibler
Bob Glass
Sue Gmeinder
Paul John Grayson
Mickey Greenberg
Jackie Greshik
Debra A. Griffith
Andy Hesselbach
Ken Jelinek
One-Jang Jeng
Jeff Jentz
Andrea Johnson
Tim Jones
Dennis Jones
Tracy Kidd
Kimberly Kline
Fritz Klode
Jeff Kolff
Yueh-Chuan Kung
Dennis La Buda
Chris LaPorte
Charles Lee
David J. Lee
Seongil Lee
Patti Lindstrom
Fred Lupton
Robert Lynch
Diane Meyers
James Mueller
Young Lae Park
Lawrence Scadden
Joseph Schauer
Debbie Schlais
Lisa Schroeder-Omar
Debbie Sherman
Paul Sura
Jeff Tackes
Sidney Tang
Christine Thompson
Mike Thompson
Michelle S. Vandall
John Ward
Dawn Wadzinski
Steven Wiker
Greg Wierman
Marcy Worzala
Chien-Ling Yang
Thomas Yen
Dave Zehel

A special thanks to Christine J. Thompson, who assisted in the preparation of many of the graphics in this document.

ABOUT THE AUTHORS

The authors of this document are too numerous and diverse to easily identify and include the compilers, those listed in the acknowledgements, those cited in the text and an even greater number of individuals whose ideas have filtered down through the grapevine and are captured here. This document represents their ideas as compiled and extended by Gregg C.Vanderheiden and Katherine R. Vanderheiden.

Gregg Vanderheiden is an associate professor in the Industrial Engineering Department's Human Factors Program at the University of Wisconsin-Madison and Director of the Trace Research and Development Center at the University (a Rehabilitation Engineering Center focusing on access to communication, computer and electronic devices by people with disabilities). Dr. Vanderheiden has been active in the field of technology and disability for over 20 years, has published numerous papers, chapters and books and has been principal investigator on over 40 grants and contracts in the area.

Katherine Vanderheiden is an independent business and professional education consultant. She is a CPA with 10 years experience in industry, including public accounting, serving as a computer systems implementation coordinator for a large hospital and developing training courses and materials for internal and industry use in her capacity as Manager in the Education Consulting Division of Arthur Andersen & Co.

PART I - Introduction

Background
Purpose of this Document
What is Accessible Design?
Four Ways to Make Products More Accessible
1. Direct Accessibility
2. Accessibility via Standard Options or Accessories
3. Compatibility With Third Party Assistive Devices
4. Facilitation of Custom Modifications
The Best Approach

PART II - Disabilities and Specific Barriers to Accessibility

Visual Impairments
Hearing Impairments
Physical Impairments
Cognitive/Language Impairments
Seizure Disorders
Multiple Impairments

PART III - Guidelines for More Accessible Design

Structure and Organization of the Guidelines
Designer's Dilemma: Availability and Meaningfulness of Numbers
Solomon's Trap
Resolving Conflicting Recommendations
SECTION 1 OUTPUT / DISPLAYS
SECTION 2 INPUT/CONTROLS
SECTION 3 MANIPULATIONS
SECTION 4 DOCUMENTATION
SECTION 5 SAFETY

References and Resources

Appendix: Guidelines Checklist

GUIDELINES BY SECTION

SECTION 1 - OUTPUT / DISPLAYS

Maximize the number of people who can/will ...

SECTION 2 - INPUT / CONTROLS

Maximize the number of people who can ...

SECTION 3 - MANIPULATIONS

Maximize the number of people who can ...

SECTION 4 - DOCUMENTATION

Maximize the number of people who can ...

SECTION 5 - SAFETY

Maximize the number of people who can ...

PART I - Introduction

Background

Beginning in 1984, joint government/industry efforts have attempted to address the accessibility of standard computer hardware and software by people with disabilities. One of the major results of these efforts was the development of design guidelines for use by computer manufacturers and software developers . These guidelines were prepared at the request of the computer companies to assist them in better understanding accessibility problems in computer design and to identify commercially practical strategies for making their products more accessible. The guidelines were developed using a cooperative industry-consumer-researcher-government consortium in order to provide the best information from all angles. The resulting guidelines (titled: Considerations in the Design of Computers and Operating Systems to Increase Their Accessibility to People with Disabilities) have been used by most major computer manufacturers in their ongoing efforts to make their products more accessible and usable by people with various types and degrees of disability. The Considerations document is a working document, and as such is continually evolving and improving (the current version is 4.2).

Purpose of This Document

This document represents a similar cooperative effort to develop design guidelines for the design of "consumer products." For this document, consumer products are defined as appliances and other electronic and mechanical devices available to the mass market for use in the home, school, office, or for use by the general public in the community. The purpose of these guidelines is 1) to point out problems encountered by people with various disabilities in using standard consumer products, and 2) to propose design alternatives which will result in increased usability of standard products by people with disabilities.

As with the computer guidelines, this document is designed to be purely informational in nature, and has been developed at industry's request to facilitate product designers' efforts to make their products more accessible. It represents the compilation of information from many sources and, as a working document, is under continual revision. To that end, comments and suggested revisions are solicited from all readers, particularly from product designers.

What is Accessible Design?

"Accessible Design" is the term used for the process of extending mass market product design to include people who, because of personal characteristics or environmental conditions, find themselves on the low end of some dimension of performance (e.g., seeing, hearing, reaching, manipulating). Accessible Design is not (or should not be) separate from standard mass market design. Rather it is an extension or elaboration of general design principles to cover a wider range of human abilities/limitations than has traditionally been included in product design.

Thus Accessible Design is a subset of what is termed Universal Design. Where Universal Design covers the design of products for all people and encompasses all design principles, Accessible Design focuses on principles that extend the standard design process to those people with some type of performance limitation (the lower ability tail of Universal Design).

Accessible Design is a balancing act. To begin with, we must acknowledge that it is not possible to design everything so that it can be used by everyone. There will always be someone with a combination of severe physical, sensory and cognitive impairments who will not be able to use it. However, it is equally unreasonable to rely on the existence (or development) of special designs for each major product to accommodate each one of the immense variety of disabilities (and combinations of disabilities). This makes it necessary to look toward a combination of approaches for meeting the needs of people with disabilities, ranging from the incorporation of features into products that will make them directly usable ("from the box") by more people with disabilities to the inclusion of features that make them easier to modify for accessibility.

Four Ways to Make Products More Accessible

Four different approaches to making products more accessible are discussed in this section and reflected in the Guidelines. In any one product, it may be necessary to use one or a combination of these approaches to achieve the desired level of accessibility. These approaches, in order of desirability, are:

Direct Accessibility
Accessibility via Standard Options or Accessories (from the manufacturer)
Compatibility with Third Party Assistive Devices
Facilitation of Custom Modifications

1. Direct Accessibility:

For most types or degrees of impairment, there are simple and low cost (or no cost) adaptations to product designs which can significantly increase their accessibility and usefulness to individuals with functional impairments. By incorporating these design modifications into the initial product design, the standard product can be more accessible directly "out of the box."
Inclusion of these design features or approaches in the standard product can be of substantial benefit to society as a whole to the extent it enables individuals with disabilities to lead more independent and productive lives. As an additional bonus, it has often been found that designs which are accessible to people with more limited abilities may benefit other users (without disabilities or impairments) as well by reducing fatigue, increasing speed, decreasing the number of errors made and decreasing learning time.
Some examples.
In the personal computer industry, particular attention has been focused on Accessible Design in recent years, and access features are beginning to show up as direct components of standard computer products. A "MouseKeys" feature, for example, is now a standard part of all Apple Macintosh™ computers shipped. This feature, which can be invoked directly from the keyboard, allows the user to move the cursor across the screen via the numeric keypad rather than the mouse. Individuals who do not have the motor control necessary to operate a mouse can use this feature (which is built into all Macintoshes) to access the Macintosh. Because the feature is implemented as an extension to the computer's operating system, it costs nothing to include as part of the product. Since "MouseKeys" became available, many able-bodied users have found it useful as well because of its capability for precise one-pixel positioning, which was not previously available.
Other examples of direct accessibility include MacDonald's, who embossed braille characters on the tops of its soft drink cup covers along with the letters labelling the pushdown buttons on the lid that indicate whether the drink is diet, etc., and Proctor-Silex, who embossed braille characters on the bottom of some of its bowls indicating the size (quarts) of the bowl.

2. Accessibility via Standard Options or Accessories (from the manufacturer):

Sometimes it is not possible to design the standard product to make it directly accessible for some disability populations. Alternatives to standard design may be identified, but offering all of them may not be practical due to some alternatives being mutually exclusive, too expensive, or awkward as a standard product.
When this occurs, it may be more effective to make these adaptations or alternatives available as standard options or accessories from the manufacturer. These may be extra-cost, special order items, or preferrably, items available free on request. These special features or accessories should be listed and described in the standard documentation that comes with the product. They could also be listed in advertising for the product.
An example.
Microwave ovens are often made with smooth glass control panels. That is, there are no tactilely discernable buttons. This can present a problem for people with visual impairments. Ideally, the control panel should be designed with ridges around each button and some type of tactile identification of button function. If this is not possible, the manufacturer may make available either a raised letter or braille overlay. These could be available free upon request. (Information on how to order the optional accessories should then be prominently presented in the product installation and operating instructions). The Sharp Carousel II (TM) is one such microwave that offers a braille overlay as an option.

3. Compatibility With Third Party Assistive Devices:

3a. Compatibility with Special Interfaces or Accessories

Sometimes direct accessibility, or even the use of standard options, is impractical for the mass market producer to provide for all disability types and degrees. This is particularly true for individuals with severe or multiple impairments (e.g., a person with a severe physical disability may be unable to use a standard keyboard even with accessibility features built in). In these cases, special interfaces or accessories may be available from third party assistive device manufacturers.
Some examples.
The mass market manufacturer can facilitate the efforts of third party manufacturers in a number of ways, including using standard approaches, providing appropriate connection points, providing advance access to new versions of products, and providing technical assistance in understanding and properly attaching accessories to the product. Consideration in the design of a keyboard, for example, could make it easier for third parties to develop keyguards and other keyboard accessories.

3b. Compatibility with General Purpose Assistive Devices

In some cases, people with particular disabilities may already have general purpose assistive devices which they would like to be able to use in conjunction with a product (e.g., a person with an eye gaze communication aid would like to be able to use it in conjunction with home electronic appliances; an individual with artificial hands or a hook would like to be able to operate the handles on appliance doors; a blind person with a dynamic braille display would like to use it with home information systems). Unfortunately, it is often difficult or impossible to connect the assistive devices to standard products.
Cooperation between mass manufacturers and assistive device manufacturers could result in standard or built-in product connection points (connectors or infra-red links) which facilitate the connection of special devices as well as properly designed hardware to facilitate the use of assistive manipulation devices.
An example.
Many people with physical disabilities cannot use standard computer keyboards. Some of these people would require more extensive modifications than would be possible using the first two accessibility approaches discussed. Currently, there are assistive device manufacturers who make alternative input devices to fit people with a variety of severe physical disabilities. However, the manufacturers of these assistive devices have always had problems ensuring that the devices would work with standard, commercially available computers. As part of the effort by the computer industry to cooperate with manufacturers of assistive devices, both IBM & Microsoft Corporation now distribute an extension to their operating systems (DOS & Windows) called "SerialKeys." This extension allows people to connect alternative input devices to the serial port of the standard personal computer in a way which makes input to the serial port look like it is coming directly from the standard keyboard and mouse. In this fashion, the user with a disability can completely access and control the computer and all of its software from an alternate input system without touching the standard keyboard or mouse.

4. Facilitation of Custom Modifications:

There may be some cases where all the other approaches to Accessible Design prove to be impractical or uneconomical, most likely for people with combinations or severe disabilities.
In such cases, custom modifications of the product, either by the product manufacturer or a third party, may be the best solution. Standard product manufacturers should facilitate this as much as they can. For example, leaving room for special attachments or labels, documenting hooks or places to patch into hardware or software, publishing information on safe or effective ways to modify products, or honoring warrantees for products which have been modified for accessibility but where the modification did not result in the problem.
An Example:
After-market adaptation of automobiles (particularly vans) for use by drivers with physical impairments is being facilitated in this way. As more standards are developed through cooperative efforts by auto manufacturers, adaptive specialists, and consumers, possibilities for help from the auto manufacturers will improve. Currently, Chrysler pays the first $500 for after-market adaptation of its vans for people with disabilities. General Motors now pays up to $1,000 reimbursement of adaptive equipment and installation costs on eligible vehicles, and provides listings of driver assessment facilities, mobility equipment dealers, and organizations offering services in transportation, as well as a GM wheelchair compatibility listing and resource video.

The Best Approach

Of the four approaches to Accessible Design, the first type, direct accessibility "from the box," is the best where it is possible. It allows the greatest access to products by persons with disabilities at the lowest cost. It also allows them to access products in public places where they could not otherwise modify the products to meet their particular needs. It also removes the stigma of "special" aids or modifications. This is especially important for older users who do not want to be labeled "disabled" even though their abilities are weakening.

It should also be noted that most of us become temporarily "disabled" in a number of ways throughout our lives. Sometimes it is by accident, such as a broken arm or eye injury. Sometimes it is by circumstance, such as operating things in the dark where we can't see well, in loud environments (vacuuming or teenagers) where we can't hear well, with things in our arms where we can't reach well, when we're tired or on cold medication and can't think well, etc. Only those products which were designed to be more easily used directly "from the box" (#1 above) will be of use to us then. As mentioned above, more accessible designs are also usually easier to use by everyone all the time - but only if the ease of use is directly built in.

PART II - Disabilities and Specific Barriers to Accessibility

Prior to reviewing the Guidelines presented in Part III, the reader who is not familiar with the demographics, causes and effects of major types of disabilities would benefit greatly from reviewing this section. The Guidelines assume a basic familiarity with this information. In addition, it is likely that new advances in design are not anticipated by the Guidelines. In those cases, knowledge of the basic characteristics of various disabilities will enable manufacturers to anticipate the effect of major design changes on their products' accessibility

A significant portion of our population (over thirty million in the U.S.) has impairments which reduce their ability to effectively or safely use standard consumer products. These impairments may be acquired at birth or through accident or disease. Note that many impairments which result in disabilities are associated with aging. This is especially significant, as the population as a whole is growing older. Although there is a tremendous variety of specific causes, as well as combinations and severity of disabilities, we can most easily relate their basic impact to the use of consumer products by looking at four major categories of impairment. The four categories are:

Visual Impairments
Hearing Impairments
Physical Impairments
Cognitive/Language Impairments

In addition, we will discuss the special case of seizure disorders as well as some of the common situations of multiple impairments.

Visual Impairments

Visual impairment represents a continuum, from people with very poor vision, to people who can see light but no shapes, to people who have no perception of light at all. However, for general discussion it is useful to think of this population as representing two broad groups: those with low vision and those who are legally blind. There are an estimated 8.6 million people with visual impairments (3.4% of the U.S. population). In the elderly population the percentage of persons with visual impairments is very high.

A person is termed legally blind when their visual acuity (sharpness of vision) is 20/200 or worse after correction, or when their field of vision is less than 20 degrees in the best eye after correction. There are approximately 580,000 people in the U.S. who are legally blind.

Low vision includes problems (after correction) such as dimness of vision, haziness, film over the eye, foggy vision, extreme near- or farsightedness, distortion of vision, spots before the eyes, color distortions, visual field defects, tunnel vision, no peripheral vision, abnormal sensitivity to light or glare, and night blindness. There are approximately 1.8 million people in the U.S. with severe visual impairments who are not legally blind.

Many diseases causing severe visual impairments are common in those who are aging (glaucoma, cataracts, macular degeneration, and diabetic retinopathy). With current demographic trends toward a larger proportion of elderly, the incidence of visual impairments will certainly increase.

Functional Limitations Caused by Visual Impairments

Those who are legally blind may still retain some perception of shape and contrast or of light vs. dark (the ability to locate a light source), or they may be totally blind (having no awareness of environmental light).

Those with visual impairments have the most difficulty with visual displays and other visual output (e.g., hazard warnings). In addition, there are problems in utilizing controls where labelling or actual operation is dependent on vision (e.g., where eye-hand coordination is required, as with a computer "mouse"). Written operating instructions and other documentation may be unusable, and there can be difficulties in manipulation (e.g., insertion/placement, assembly).

Because many people with visual impairments still have some visual capability, many of them can read with the assistance of magnifiers, bright lighting and glare reducers. Many such people with low vision are helped immensely by use of larger lettering, sans-serif typefaces, and high contrast coloring.

Those with color blindness may have difficulty differentiating between certain color pairs. This generally doesn't pose much of a problem except in those instances when information is color coded or where color pairs are chosen which result in poor figure ground contrast.

Key coping strategies for people with more severe visual impairments include the use of braille and large raised lettering. Note, however, that braille is preferred by only 10% of blind people (normally those blind from early in life). Raised lettering must be large and is therefore better for indicating simple labels than for extensive text.

Hearing Impairments

Hearing impairment is one of the most prevalent chronic disabilities in the U.S. Approximately 22 million people in the U.S. (8.2%) have hearing impairments. Of those, 2.4 million have severe to profound impairments.

Hearing impairment means any degree and type of auditory disorder, while deafness means an extreme inability to discriminate conversational speech through the ear. Deaf people, then, are those who cannot use their hearing for communication. People with a lesser degree of hearing impairment are called hard of hearing. Usually, a person is considered deaf when sound must reach at least 90 decibels (5 to 10 times louder than normal speech) to be heard, and even amplified speech cannot be understood.

Hearing impairments can be found in all age groups, but loss of hearing acuity is part of the natural aging process. 23% of those aged 65 to 74 have hearing impairments, while almost 40% over age 75 have hearing impairments. The number of individuals with hearing impairments will increase with the increasing age of the population and the increase in the severity of noise exposure.

Hearing impairment may be sensorineural or conductive. Sensorineural hearing loss involves damage to the auditory pathways within the central nervous system, beginning with the cochlea and auditory nerve, and including the brain stem and cerebral cortex (this prevents or disrupts interpretation of the auditory signal). Conductive hearing loss is damage to the outer or middle ear which interferes with sound waves reaching the cochlea. Causes include heredity, infections, tumors, accidents and aging (presbycusis, or "old hearing").

Functional Limitations Caused by Hearing Impairments

The primary difficulty for individuals with hearing impairment in using standard products is receiving auditory information. This problem can be compensated for by presenting auditory information redundantly in visual and/or tactile form. If this is not feasible, an alternative solution to this problem would be to provide a mechanism, such as a jack, which would allow the user to connect alternative output devices. Increasing the volume range and lowering the frequency of products with high pitched auditory output would be helpful to some less severely impaired individuals. (Progressive hearing loss usually occurs in higher frequencies first.)

Although not prevalent yet, there is much talk of using voice input on commercial products in the future. This, too, will present a problem for many deaf individuals. While many have some residual speech, which they work to maintain, those who are deaf from birth or a very early age often are also nonspeaking or have speech that cannot be recognized using current voice input technology. Thus, alternatives to voice input will be necessary to these individuals to access products with voice input.

Familiar coping strategies for hearing impaired people include the use of hearing aids, sign language, lipreading and TDD's (telecommunication devices for the deaf). Some hearing aids are equipped with a "T-coil" as well, which provides direct inductive coupling with a second coil (such as in a telephone receiver) in order to reduce ambient noise. Some other commercial products could make use of this capability.

ASL (American Sign Language) is commonly used by people who are deaf. It should be noted, however, that this is a completely different language from English. Thus, deaf people who primarily use ASL may understand English only as a second language, and may therefore not be as proficient with English as native speakers.

Finally, telecommunication devices for the deaf (TDD's) are becoming more common in households and businesses as a means for deaf and hard of hearing people to communicate over the phone. TDD's have always used the Baudot code, but newer ones receive both Baudot and ASCII.

Physical Impairments

Functional Limitations Caused by Physical Impairments

Problems faced by individuals with physical impairments include poor muscle control, weakness and fatigue, difficulty walking, talking, seeing, speaking, sensing or grasping (due to pain or weakness), difficulty reaching things, and difficulty doing complex or compound manipulations (push and turn). Individuals with spinal cord injuries may be unable to use their limbs and may use "mouthsticks" for most manipulations. Twisting motions may be difficult or impossible for people with many types of physical disabilities (including cerebral palsy, spinal cord injury, arthritis, multiple sclerosis, muscular dystrophy, etc.).

Some individuals with severe physical disabilities may not be able to operate even well-designed products directly. These individuals usually must rely on assistive devices which take advantage of their specific abilities and on their ability to use these assistive devices with standard products. Commonly used assistive devices include mobility aids (e.g., crutches, wheelchairs), manipulation aids (e.g., prosthetics, orthotics, reachers) communication aids (e.g., single switch-based artificial voice), and computer/device interface aids (e.g., eyegaze-operated keyboard).

Nature and Causes of Physical Impairments

Neuromuscular impairments include:

paralysis (total lack of muscular control in part or most of the body),
weakness (paresis; lack of muscle strength, nerve enervation, or pain), and
interference with control, via spasticity (where muscles are tense and contracted), ataxia (problems in accuracy of motor programming and coordination), and athetosis (extra, involuntary, uncontrolled and purposeless motion).

Skeletal impairments include joint movement limitations (either mechanical or due to pain), small limbs,missing limbs, or abnormal trunk size.

Some major causes of these impairments are:

Arthritis. Arthritis is defined as pain in joints, usually reducing range of motion and causing weakness. Rheumatoid arthritis is a chronic syndrome. Osteoarthritis is a degenerative joint disease. 31.6 million people in the U.S. suffer from rheumatic disease. The incidence of all forms of arthritis is now estimated at 900,000 new cases per year.

Cerebral Palsy (CP). Cerebral palsy is defined as damage to the motor areas of the brain prior to brain maturity (most cases of CP occur before, during or shortly following birth). There are more than 750,000 in the U.S. with CP (children and adults), and 15,000 infants are born each year with CP. CP is a type of injury, not a disease (although it can be caused by a disease), and does not get worse over time; it is also not "curable." Some causes of cerebral palsy are high temperature, lack of oxygen, and injury to the head. The most common types are: (1) spastic, where the individual moves stiffly and with difficulty, (2) ataxic, characterized by a disturbed sense of balance and depth perception, and (3) athetoid, characterized by involuntary, uncontrolled motion. Most cases are combinations of the three types.

Spinal Cord Injury. Spinal cord injury can result in paralysis or paresis (weakening). The extent of paralysis/paresis and the parts of the body effected are determined by how high or low on the spine the damage occurs and the type of damage to the cord. Quadriplegia involves all four limbs and is caused by injury to the cervical (upper) region of the spine; paraplegia involves only the lower extremities and occurs where injury was below the level of the first thoracic vertebra (mid-lower back). There are 150,000 to 175,000 people with spinal cord injuries in the U.S., with projected annual increases of 7,000 - 8,000. 47% of spinal cord injuries result in paraplegia; 53% in quadriplegia. Car accidents are the most frequent cause (38%), followed by falls and jumps (16%) and gunshot wounds (13%).

Head Injury (cerebral trauma). The term "head injury" is used to describe a wide array of injuries, including concussion, brain stem injury, closed head injury, cerebral hemorrhage, depressed skull fracture, foreign object (e.g., bullet), anoxia, and post-operative infections. Like spinal cord injuries, head injury and also stroke often results in paralysis and paresis, but there can be a variety of other effects as well. Currently about one million Americans (1 in 250) suffer from effects of head injuries, and 400,000 - 600,000 people sustain a head injury each year. However, many of these are not permanently or severely disabled.

Stroke (cerebral vascular accident; CVA). The three main causes of stroke are: thrombosis (blood clot in a blood vessel blocks blood flow past that point), hemorrhage (resulting in bleeding into the brain tissue; associated with high blood pressure or rupture of an aneurism), and embolism (a large clot breaks off and blocks an artery). The response of brain tissue to injury is similar whether the injury results from direct trauma (as above) or from stroke. In either case, function in the area of the brain affected either stops altogether or is impaired.

Loss of Limbs or Digits (Amputation or Congenital). This may be due to trauma (e.g., explosions, mangling in a machine, severance, burns) or surgery (due to cancer, peripheral arterial disease, diabetes). Usually prosthetics are worn, although these do not result in full return of function. The National Center for Health Statistics of the U.S. Public Health Service estimated a prevalence of 311,000 amputees in 1970. An incidence of approximately 43,000 new amputations per year is estimated, of which 77% occur in males, and 90% involve the legs. 40% of amputations are above the knee, 50% are below the knee, and 10% are at the hip.

Parkinson's Disease. This is a progressive disease of older adults characterized by muscle rigidity, slowness of movements, and a unique type of tremor. There is no actual paralysis. The usual age of onset is 50 to 70, and the disease is relatively common - 187 cases per 100,000.

Multiple Sclerosis (MS). Multiple sclerosis is defined as a progressive disease of the central nervous system characterized by the destruction of the insulating material covering nerve fibers. The problems these individuals experience include poor muscle control, weakness and fatigue, difficulty walking, talking, seeing, sensing or grasping objects, and intolerance of heat. Onset is between the ages of 10 and 40. This is one of the most common neurological diseases, affecting as many as 500,000 people in the U.S. alone.

ALS (Lou Gehrig's Disease). ALS (Amyotrophic Lateral Sclerosis) is a fatal degenerative disease of the central nervous system characterized by slowly progressive paralysis of the voluntary muscles. The major symptom is progressive muscle weakness involving the limbs, trunk, breathing muscles, throat and tongue, leading to partial paralysis and severe speech difficulties. This is not a rare disease (5 cases per 100,000). It strikes mostly those between age 30 and 60, and men three times as often as women. Duration from onset to death is about 1 to 10 years (average 4 years).

Muscular Dystrophy (MD). Muscular dystrophy is a group of hereditary diseases causing progressive muscular weakness, loss of muscular control, contractions and difficulty in walking, breathing, reaching, and use of hands involving strength. About 4 cases in 100,000 are reported.

Cognitive/Language Impairments

Functional Limitations Caused by Cognitive/Language Impairments

The type of cognitive impairment can vary widely, from severe retardation to inability to remember, to the absence or impairment of specific cognitive functions (most particularly, language). Therefore, the types of functional limitations which can result also vary widely.

Cognitive impairments are varied, but may be categorized as memory, perception, problem-solving, and conceptualizing disabilities. Memory problems include difficulty getting information from short-term storage, long term and remote memory. This includes difficulty recognizing and retrieving information. Perception problems include difficulty taking in, attending to, and discriminating sensory information. Difficulties in problem solving include recognizing the problem, identifying, choosing and implementing solutions, and evaluation of outcome. Conceptual difficulties can include problems in sequencing, generalizing previously learned information, categorizing, cause and effect, abstract concepts, comprehension and skill development. Language impairments can cause difficulty in comprehension and/or expression of written and/or spoken language.

There are very few assistive devices for people with cognitive impairments. Simple cuing aids or memory aids are sometimes used. As a rule, these individuals benefit from use of simple displays, low language loading, use of patterns, simple, obvious sequences and cued sequences.

Types and Causes of Cognitive/Language Impairments

Mental Retardation. A person is considered mentally retarded if they have an IQ below 70 (average IQ is 100) and if they have difficulty functioning independently. An estimated 3% of Americans are mentally retarded. For most, the cause is unknown, although infections, Down Syndrome, premature birth, birth trauma, or lack of oxygen may all cause retardation. Those considered mildly retarded (80-85%) have an IQ between 55 and 69 and are considered educable, achieving 4th to 7th grade levels. They usually function well in the community and hold down semi-skilled and unskilled jobs. People with moderate retardation (10%) have an IQ between 40 and 54 and are trainable in educational skills and independence. They can learn to recognize symbols and simple words, achieving approximately a 2nd grade level. They often live in group homes and work in sheltered workshops. People with severe or profound retardation represent just 5-10% of this population.

Language and Learning Disabilities. Aphasia, an impairment in the ability to interpret or formulate language symbols as a result of brain damage, is frequently caused by left cerebral vascular accident (stroke) or head injury. Specific learning disabilities are chronic conditions of presumed neurological origin which selectively interfere with the development, integration, and/or demonstration of verbal and/or non-verbal abilities. Many people with learning disabilities are highly intelligent aside from their specific learning disability. 1-8% of school-aged children and youth have specific learning disabilities.

Age-Related Disease. Alzheimer's disease is a degenerative disease that leads to progressive intellectual decline, confusion and disorientation. Dementia is a brain disease that results in the progressive loss of mental functions, often beginning with memory, learning, attention and judgment deficits. The underlying cause is obstruction of blood flow to the brain. Some kinds of dementia are curable, while others are not.

Seizure Disorders

A number of injuries or conditions can result in seizure disorders. Epilepsy is a chronic neurological disorder. It is reported that approximately 1 person in 15 has a seizure of some sort during his life, and between .5% and 1.5% of the general population have chronic, recurring seizures. A seizure consists of an explosive discharge of nervous tissue, which often starts in one area of the brain and spreads through the circuits of the brain like an electrical storm. The seizure discharge activates the circuits in which it is involved and the function of these circuits will determine the clinical pattern of the seizure. Except at those times when this electrical storm is sweeping through it, the brain is working perfectly well in the person with epilepsy. Seizures can vary from momentary loss of attention to grand mal seizures which result in the severe loss of motor control and awareness. Seizures can be triggered in people with photosensitive epilepsy by rapidly flashing lights, particularly in the 10 to 25 Hz range.

Multiple Impairments

It is common to find that whatever caused a single type of impairment also caused others. This is particularly true where disease or trauma is severe, or in the case of impairments caused by aging.

Deaf-blindness is one commonly identified combination. Most of these individuals are neither profoundly deaf nor legally blind, but are both visual and hearing impaired to the extent that strategies for deafness or blindness alone won't work. People with developmental disabilities may have a combination of mental and physical impairments that result in substantial functional limitations in three or more areas of major life activity. Diabetes, which can cause blindness, also often causes loss of sensation in the fingers. This makes braille or raised lettering impossible to read. Cerebral palsy is often accompanied by visual impairments, by hearing and language disorders, or by cognitive impairments.

PART III - Guidelines for More Accessible Design

Structure and Organization of the Guidelines

In order to facilitate use by product design teams, this section is organized functionally rather than by disability area. Functional categories are as follows:

Output/Displays

Input/Controls includes keyboards and all other means of communicating to the product

Manipulations includes all actions that must be directly performed by a person in concert with the product or for routine maintenance; e.g., inserting disk, loading tape, changing ink cartridge

Documentation primarily operating instructions

Safety includes alarms and protection from harm

Each guideline is phrased as an objective, followed by a statement of the problem(s) faced by people with disabilities. The problem statement is accompanied by more specific examples. Next, "design options and ideas" are presented to provide some suggestions as to how the objective could be achieved. Readers are encouraged to think of other ideas. Finally, additional data and specific information, along with illustrations, are presented at the end of each guideline.

The guidelines are stated as generically as possible. Therefore, all, some or none of the design options and ideas presented may apply in the case of any specific product. The recommended approach is to implement those options which together go the longest way toward achieving the objective of the guideline for your product. It is understood that this is not an ideal world, so it may currently be too expensive to implement all those ideas which would best achieve the objective. It is also anticipated that there will be other ways of meeting accessibility objectives than those discussed here, and such discoveries are encouraged. We would like to hear of them so that they can be included in future releases of these Guidelines.

Designer's Dilemma: Availability and Meaningfulness of Numbers

In trying to make products more accessible, the question of numbers quickly arises. How large should lettering be? What size button is large enough? How much pressure is too much, or not enough? In trying to make designs more accessible there are two tough principles that one has to come to grips with early.

You cannot make a product absolutely accessible. You can make it more accessible, but there will always be people who cannot use it.
Therefore... There are no magic numbers. There are no numbers to tell you that you have gone far enough and nothing more will help anyone.

At first this is hard to accept. Everyone wants a number to design to. Occasionally minimal numbers for minimal required accessibility are set, but ...

They only can be set for a particular type of device (a phone, an elevator button, etc.).

They only specify a minimum accessibility threshold (usually required by law or regulation).

The Problem with Diversity of Types and Degrees of Impairment

This latter point is the most important. A key problem in picking or setting a number is deciding who to leave out. The reason for discussing accessible design in the first place is that the standard design process currently only targets "most" of the people, and then stops. Some target number is established that is "good enough" to cover 80%, 90% or 95% of the people, and then developers end up designing to that number and stopping - even if they could just have easily gone a bit further. And it is that last phrase that is important. Since no product can be made completely accessible, a designer can't ever win completely. Tough to accept or deal with, but a fact of life. The secret, then, is to go as far as one can in making the design accessible. Setting a number as "good enough" for "most people with disabilities" and then designing to it just repeats the mistake that was made in the standard design process.

For example, to specify exactly how large lettering should be in order to be visible, you must first ask "visible to whom?" For any number you cite, there will be people who could see it if it were just a little bigger and others who would be unable to read it if you made it any smaller. There would also be some who could not see it no matter how large you made it. Thus, there is no number that will allow all people to read it. You always end up leaving some people off. The question then isn't "How large must lettering be to be accessible?" The proper question is "How large can this lettering be and still work for this product?" The decision to make it as large as practical will make the product accessible to a greater number of people. However, the decision as to the exact amount of enlargement that can be effectively used on the lettering for any given product is a decision that must be made as a part of the design process for that specific product.

Numbers Do Have their Place

This is not to say that numbers are not useful. They are essential to any design process. The numbers needed, however, are not "target" numbers or "this is now accessible" numbers, but rather numbers that a designer can use as milestones to see how changes in a design will affect users. Whenever data of this type exist or are identified they will be either included or cited in these Guidelines. An example of this is Figure O-7-a on the sensitivity of people with photosensitive epilepsy to different flicker frequencies. The chart does not give a magic frequency that would be safe (wouldn't trigger a seizure in anyone) under all conditions. It does, however, clearly indicate that avoiding 20 hz flicker by as much as practical will clearly be to the benefit of those with photosensitive epilepsy.

Occasionally, recommended "minimum" or "maximum" values do exist. Sometimes they are created as part of regulations or standards which set a baseline that everyone must comply with for some product or market. In other cases, "rule of thumb" values exist which are known or believed to cover the majority of people or situations. As the new accessibility standards for ADA compliance are finalized, for example, those that might apply to consumer products will be included in these Guidelines for reference. In all cases, however, these values should be used as milestones and not as absolute or "good enough" design targets. If it is possible to go beyond the value and create a more accessible design, then that should be considered.

The Role of These Guidelines

The role of these Guidelines, then, is more to raise the awareness and understanding of designers and to help them ask the right questions than to provide specific answers or numbers. Notwithstanding, wherever specific design ideas or "recommendable" values do exist, they are provided. When they do not, general recommendations or design ideas are provided to help designers identify areas where attention can increase accessibility. In addition, data are provided when available to help designers measure the impact of various design decisions or tradeoffs.

The Role of the Designer

In all cases, however, the exact values to use for a given product design will have to be determined by balancing the various design factors and constraints for that particular product. They cannot be dictated a priori without picking a number which will be too restrictive for some designs and unnecessarily loose for others.

Solomon's Trap

Often, initial attempts at accessible design are done piecemeal. Accessible features are added where they are obvious rather than as a result of looking at the product's overall accessibility. The result can be a design which has accessible parts, but is not as a whole accessible or usable. Access to half a product when the rest is inaccessible is of little practical use.

In some cases, inspired by a desire to address the needs of people with different disabilities, it is even possible to design some parts of a device (such as the controls) to be more accessible to one population and design another part of the product with another disability in mind. Unless the whole product is accessible to at least one of these populations no-one is served.

In most cases it is possible with careful design to create products which are simultaneously accessible to people with different impairments. However, where this is not possible, care should be taken to be sure that the entire product is accessible to those disability populations that you are able to address. Giving half a product to one disability group and the other half of the product to another is not helpful to or desired by any of the disability groups.

Resolving Conflicting Recommendations

Sometimes a solution to a problem for one type of disability may cause a new problem for a person with another type of disability. For example, those with visual impairments may be helped by replacing a visual readout with auditory output, but this would in turn cause a problem for those with hearing impairments. As such situations arise, the Guidelines will attempt to highlight them and suggest ways to avoid or minimize any potential conflicts.

At the end of most sections, a summary of the recommendations, along with examples of balanced solutions, is presented. These are not the only, and perhaps not the best, solutions. They do, however, show how multiple recommendations can be addressed even when they seem to be contradictory. They also illustrate that it is usually impossible to follow all of the recommendations simultaneously.

NOTE: The ADA guidelines are currently under development and the ANSI standards for accessibility are currently under revision. When these activities are completed, specifications for minimum levels of accessibility for some types of structures and products will be spelled out. As these minimum values are defined they will be added to these guidelines in the sections to which they apply. To avoid confusion existing and proposed standards are not included in this draft.

SECTION 1: OUTPUT / DISPLAYS. Includes all means of presenting information to the user

Maximize the number of people who can/will ...

O-1 hear auditory output clearly enough

O-2 not miss important information if they can't hear.

O-3 have line of sight to visual output and reach printed output.

O-4 see visual output clearly enough.

O-5 not miss important information if they can't see.

O-6 understand the output (visual, auditory, other).

O-7 view the output display without triggering a seizure.

O-1. Maximize the number of people who can... hear auditory output clearly enough.

Problem:

Information presented auditorially (e.g., synthesized speech, cuing and warning beeps, buzzers, tones, machine noises) may not be effectively heard.

Examples:

Individuals who have mildly to moderately impaired hearing may not be able to discern sounds that are too low in volume.
Individuals who have mild hearing impairments may be unable to turn the volume up sufficiently in some environments (e.g., libraries, where others would be disturbed, or in noisy environments, where even the highest volume is insufficient).
People with moderate hearing impairments are often unable to hear sounds in higher frequencies (above 2000 Hz).
People with hearing aids may have difficulty separating background noise from from the desired auditory information.
People with cognitive impairments may be easily distracted by too much background noise.
Auditory information which is short or not repeated or repeatable (e.g., a short beep or voice message) may be missed or not understood.

NOTE: Severely hearing impaired (and deaf) people cannot use audio output at all. See O-2 for guideline to address this problem.

Design Options and Ideas to Consider:

Providing a volume adjustment, preferably using a visual volume indicator. Sound should be intelligible (undistorted) throughout the volume range.
Making audio output (or volume range if adjustable) as loud as practical.
Using sounds which have strong mid-low frequency components (500 - 3000 Hz).
Providing a headphone jack to enable a person with impaired hearing to listen at high volume without disturbing others, to enable such a person to effectively isolate themselves from background noise, and to facilitate use of neck loops and special amplifiers (see additional information below).
Providing a separate volume control for the headphone jack so that people without hearing impairments can listen as well (at standard listening levels).
When a headphone jack is not possible:
- placing the sound source on the front of the device and away from loud mechanisms would facilitate hearing.
- locating the speaker on the front of the device would also facilitate use of a small microphone and amplifier to pick up and present the information (via speaker, neckloop or vibrator).
Facilitating the direct use of the telecoil in hearing aids by incorporating a built-in inductive loop in your product (e.g., in telephone receiver's earpiece).
Reducing the amount of unmeaningful sound produced by the product (i.e., background noise).
Presenting auditory information continuously or periodically until the desired message is confirmed or acted upon. Spoken messages could automatically repeat or have a mechanism for the user to ask for them to be repeated.

Additional Information:

An adjustable and fairly loud volume is particularly helpful to aging individuals and others with mild hearing impairments who do not normally carry or use hearing aids or other sound amplification devices. (Note that many such people do not wish to acknowledge their hearing loss by wearing aids.)
Visual indication of the volume setting is important, as individuals with hearing impairments often do not know or realize the volume level is set painfully high for others. Simple strategies include a painted and/or tactile dot or arrow on a control dial, a sliding bar volume control, numbers or graphics (on a thumbwheel dial), or an on-screen bar graph volume indicator (see examples below).
Loss of hearing associated with age generally begins with the inability to hear high frequencies. Thus, use of lower frequencies will be particularly helpful to older people.
For alerting devices the use of two or more spectral components in the 500 - 4500 Hz range is recommended based on ringer studies . Others suggest limiting the upper frequency to 3000 Hz to better accommodate people with mid-high frequency loss.
When using voice output, male voices are usually preferable to female voices because of their lower pitch. Consonants which are particularly easy to hear in the male speech patterns are "m" and "n."
The use of sufficient volume and low frequency are particularly critical for alarms.
(See S-1 for guideline to specifically address this problem.)
For some products it may be feasible to have adjustable frequency of auditory output.
A (front mounted) headphone jack allows individuals with hearing impairments to carry a pair of headphones or headphones equipped with a small, battery-operated amplifier to provide the necessary sound levels.
Headphone jacks come in two sizes. The commonly used ones are 1/4" and 1/8 ". Because both are so commonly used, most headphones come with an adaptor which allows them to work with both jack sizes. As a result, either size is generally acceptable. The larger size jack is slightly easier to handle and more rugged but the smaller size is becoming the more common size due to miniaturization of equipment.
The headphone jack can be used to connect an inductive neckloop (loop which is worn around the neck and provides direct inductive coupling with the t-coil in a hearing aid).
Headphone jacks are also appreciated by non-hearing-impaired people and people with certain types of learning disabilities where use of a headphone is desirable for privacy or in both noisy and quiet environments (e.g., factory, office, or library). A separate volume control for the headphones is also useful when others would like to listen to the same output (via speakers) at a lower volume.

Figure O-1-a: A neck ring or ear loop can be plugged into a headphone jack on an audio source and provide direct inductive coupling between the audio source and a special induction coil on a person's hearing aid. This cuts out background noise that would be picked up by the hearing aid's microphone and provides clearer reception of the audio signal.

Figure O-1-b: A headphone jack permits the connection of headphones, neck/ear loops, amplifiers or sound indication lights.

Figure O-1-c: Speaker near edge and away from unwanted noise sources allows use of microphone to pick up sounds and relay on to an amplifier and speaker or neckloop. (Not as good as headphone jack.)

On-screen bar graph (need non-visual method as well); Visual (and tactile) dot; Sliding Control with Reference (Not as good for people who are blind).

Figure O-1-d: Provision of a visual indicator of volume level is useful so that people with hearing impairments can better judge the impact of volume on others in the environment.

Figure O-1-e
Hearing Loss as a Function of Age

Description of figure(s) in D-tag D

Figure O-1-f
Hearing Loss for Different Frequencies as a Function of Age

Description of figure(s) in D-tag D

Figure O-1-g
Recommended Frequency for Altering Devices

Description of figure(s) in D-tag D