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Toward universal design: an ongoing project on the ergonomics of disability.

Millions of consumer products are purchased each day. Volumes of marketing research focus on just how and why consumers select certain products. At the center of all this attention is the consumer and his/her perception of how well a product meets a given need.

One important consideration in the process of product selection is how well a product's characteristics suit the user's characteristics: Does it fit my hand comfortably? Is it easy for me to use? Can I use it safely? These and other questions are the essence of a field known as ergonomics.

Sadly, many manufacturers are not convinced that products conscientiously designed with the ergonomics of the consumer in mind are any more successful on the "bottom line" than those less well designed. This perception is partly due to the belief that consumers attach no monetary value to ergonomics and therefore additional product cost due to ergonomic features is unacceptable.

The "Real" Consumer Market

Historically, ergonomic principles were based on data developed through military research for the purpose of producing more effective weapons. Application of this data to design of commercial products for mass consumption yielded a world of consumer products most appropriate for young, fit males, i.e., soldiers. Though intended to consider the vast majority of "normal" people, these products do not necessarily serve the needs of women, very old or very young people, people with disabilities, or other "minorities" (Wiesel, 1985).

Yet, disabled people represent a large and growing segment of the consumer population--a population in great need of conscientiously, if not ergonomically, designedd products. The number of Americans with severe physical disabilities increased by more than 49 percent between 1970 and 1981 (Cherry, 1984). This increase is evidence that advances in medical technology enable people who suffer serious illnesses or injuries to survive longer and live more independently. Evidence of this increase is even more stunning when comparing spinal cord injury survival rates from 1900 to 1980; only 10 percent of people who suffered spinal cord injuries survived the injury in 1900, while by 1980 the survival rate had reached 80 percent (Cherry, 1984). Mortality rates for conditions such as kidney failure, diabetes, heart disease, and hypertension have decreased by as much as 50 percent over the past 20 years (DeJong, 1987).

The growth of the disabled population is also attributable to an older population. Anyone who lives long enough may eventually experience a disability. Functional limitations due to arthritis, heart disease, cerebrovascular disease, and eye disorders are among the most common limitations in persons 45-84 years of age (LaPlante, 1988). By the turn of the century, one-third of the U.S. population will be physically disabled, chronically ill or over 65 years of age (Business & Health, 1988). People with disabilities are clearly among the fastest growing consumer market segments in the world.

Unlike other consumers, disabled people must make most "buy" (or more frequently "no buy") decisions based on ergonomic considerations. The majority of available products so blatantly conflict with the abilities and limitations of many disabled people that appearance, durability and even price often become secondary. An example of this exists in the automotive marketplace which offers an attractive product for seemingly any consumer. Why then do so many wheelchair users restrict their choices to fullsize, two-door sedans? Large two-door sedans are rarely preferred by wheelchair users for their aesthetic appeal (or their gas mileage), but rather for the accessibility of the space behind the front seat for wheelchair storage/retrieval. Most other product features are secondary. Few wheelchair users, even wealthy ones, drive Porsches.

Conversely, products which do suit the disabled consumer's needs often come about by accident rather than by design. These products fall into favor with the disabled consumer market despite other shortcomings. Wheelchair consumers are a perfect example of this "captive" market. When any consumer compares the appearance, durability and price of a wheelchair with a 10-speed bicycle the buyer's choice is obvious. Yet, 1 out of 200 Americans uses a wheelchair and, despite many shortcomings, wheelchairs are higher priced and have less aesthetic appeal than bicycles (Office of Technology, 1984). To this group of consumers, ergonomics is not a luxury added to a proudct, but a prerequisite for any product selection.

Although disabled consumers are the exclusive users of products such as wheelchairs, walkers and hearing aids, they are also an integral part of the "mainstream" population. Disability does not prevent many people from using refrigerators, telephones, televisions, hair dryers, food processors, computers, etc. But how well these and other products suit the needs of these consumers determines their success in this important market.

It is not the purpose of this article to argue the value of ergonomics in product design, but to point out the "bottom line" value of considering the ergonomic needs of a generally ignored yet significant consumer market: people with disabilities. The consumer market is no longer merely regional, or even national. Manufacturers must now think in terms of global markets and global competition. Therefore, manufacturers must be convinced of the importance of reaching the disabled buyer. This report synthesizes available data concerning the disabled population into a format most useful in product planning, marketing and design.

In 1988 we saw the following:

* An exhibit, "Designs for Independent Living," at New York City's Museum of Modern Art from April 16 through June 7 focused on products chosen for their elegance, as well as their usability, by people with disabilities.

* A television commercial for Levis 501 Jeans featured a wheelchair user.

* WearEver/Proctor-Silex redesigned its ceramic baking dishes to include capacity markings in braille.

* A feature article in the October issue of Home magazine illustrated furnishing desirable to disabled and nondisabled people alike (Ringwald, 1988). * A clever McDonald's television commercial was communicated by two actors using only sign language, yet captioned for viewers "handicapped" by an inability to understand sign language.

These advertisements and many more like them are some of the obvious signs that Americans are becoming more aware of and more comfortable with people who have disabilities. These are also examples of how American businesses have chosen to address Americans with disabilities (as well as their families and friends) as a viable market for products and services.

Most American businesses generally have limited knowledge of this "new" market. McDonald's and Levi-Strauss are among the few U.S. companies that have taken the first step towards obtaining this knowledge and towards marketing directly to people with disabilities. Historically, lack of reliable market data concerning this population made such attempts difficult at best. Widely conflicting estimates of the total number of disabled Americans discouraged businesses from attempting to reach this apparently significant, but elusive,


John Naisbitt, author of Megatrends, offered these compelling statistics concerning the disabled consumer market in his November 24, 1988, Trend Letter:

". . . More and more, the business sector is discovering the nation's large and increasingly lucrative disabled population. Each year, 36 million disabled Americans spend $40 billion on special products ... from wheelchairs to braille versions of Monopoly and Scrabble."

Fortunately, recent nationwide surveys have yielded valuable information about the demographics and ergonomics of this population (LaPlante, 1988, U.S. Bureau of the Census, 1986). Information is now available to enable businesses to formulate effective marketing strategies to disabled consumers. It is the purpose of this report to point out the demographic data that exists for use by product designers, manufacturers and developers towards the establishment of a more "universal" approach to product design.

Universal design incorporates the ergonomics of the disabled consumers without compromising either usability or desirability by nondisabled consumers (Ringwald, 1988). Experience with this approach to design has shown that the result is better design has shown consumers. It is clear from the actions of companies such as McDonald's (which spent over $207 million on advertising in 1981) that this approach is both practical and profitable (Advertising Age, 1981).

Sources of Data

Studies of the disabled population have been conducted for a variety of purposes by a variety of consumer organizations, federal agencies and private research groups. Consequently, the usefulness of each study's data depends on the purpose for which the study was conducted. For example, consumers in need of universally designed products need not be employed (though buying power is certainly a factor) or even be of employable age. In fact, the annual discretionary income of persons over 65 is estimated to be the highest of any age group (Farmer, 1989). Therefore, studies focusing only on ages 16-64 artificially restrict estimates of the potential consumer population. The population considered as the greatest potential consumers of universal design, then, are all non-institutionalized civilians considering themselves (or are considered by their guardians to be) limited in activity due to a chronic condition (LaPlante, 1988). It is important to note that this excludes those people who report a chronic condition, but not a limitation in activity. Many people function independently despite a "disabling" condition.

The study selected for this report focuses on people who report limitations. Though perception of a limitation and clinical reality may differ, it is the consumer's perception of his/her limitations which influences the choice of consumer products. The National Health Interview Survey (NHIS) 1983-1985 has been selected for the purpose of this report. In addition to the criteria outlined above, this survey also fulfills the need for data on limitations experienced by people with a wide variety of chronic conditions. This data forms the basis for defining the target market for universal design.


According to the NHIS, 32.5 million people, or about 14.1 percent of the non-institutionalized U.S. population, report an activity limitation due to a chronic condition (LaPlante, 1988). "Activity limitation" refers to major activities normally associated with a person's age group (e.g., ordinary play for children under 5 years of age, attending school for 5 to 17-year-old children, working or keeping house for people 18-69 years old, and capacity for selfcare for those 60 years of age and older (LaPlante, 1988)). "Chronic condition" refers to a condition which has lasted at least 3 months or is on the NHIS list of conditions considered chronic, regardless of onset (LaPlante, 1988). Each of these 32.5 million people experiences at least one functional limitation which restricts independence. Though each person is unique, the NHIS outlines some general characteristics of this market on the following pages.

Disability and Age

"Except for small decreases at ages 18-24 and a sizable decrease at ages 70-74 (probably due to a redenfinition of major life activities at this age as described above), the percentage of the population with activity limitations increases with age" (LaPlante, 1988).

Despite the traditional social, political and economic differences keeping the disabled and aging populations apart, similarities in function characteristics ar unavoidable. The probability of becoming disabled increases with age. Therefore, products usable by disabled consumers will generally find a market among the aging population. This is especially true if the products do not carry with them a stigma of "handicappism." Such a "transgenerational" crossover effect influences product design and marketing and is one technique that product manufacturers are using the increase sales of both mainstream and "special" products. Data presented later regarding functional limitations illustrate the impact of age on the prevalence of specific limitations.

Disability and Buying Power

LaPlante in 1988 indicated that disability is inversely related to family income. But historically, disabled people and their families have been willing to purchase assistive devices sometimes costing upwards of $3,000. Families with disabled members often face challenges in meeting ongoing medical expenses (as well as the more ordinary needs) on a limited budget. Products intended exclusively for disabled consumers tend to be more expensive than those intended for nondisabled consumers. Therefore, disabled people are looking more and more toward mainstream products that can meet their needs at a reduced cost.

A primary example showing the crossover of the disabled consumer into the mainstream marketplace occurs with people lacking coordination or strength to dial or key in a 7- to 10-digit telephone number, which may be critical in an emergency. To solve this problem, disabled people have turned to environmental control units and emergency call systems costing more than $3,000. Integration of memory-dial and voice recognition features into modern telephones make it possible for these same manually limited people to use these updated products. Most of these products can be purchased for as little as $200 and serviced through regular dealer networks.

The bottom line buying power of people with disabilities is clearly on the rise. Considering that products such as telephones, environmental control systems, emergency call devices, and other important assistive devices may well be covered under insurance plans in the future, it is important that manufacturers begin to take notice of the disabled consumer. This will not only assist those who can already afford the products, but also make assistive devices accessible even to those who currently find them difficult to afford. Those products which best serve all consumers' needs will reach the broadest market--an outcome of universal design.

Disability and Race

"Native Americans have the highest prevalence of disability by all measures. The lowest prevalence is found for


Asian and Pacific Islanders" . . . (LaPlante, 1988).

Some 17.8 percent of Native Americans, 14.9, percent of non-Hispanic black people, 14.5 percent of non-Hispanic white people, 10-11 percent of Hispanic people, and 6.5 percent of Pacific Islanders/Asians report limitation of activity due to a chronic condition.

Geographic Distribution of

Disabled People

The NHIS did not describe the geographic distribution of disabled people. However, Table 1 depicts the proportion of disabled people 17-64 years old in each state according to the 1980 Census of Population and Housing.

Disability, Chronic Conditions and

Functional Limitations

Over 70 chronic conditions are listed in the NHIS report. Each of these has the potential for causing one or more functional limitations which create ergonomic differences between the disabled and nondisabled consumer. Translating the NHIS data on chronic conditions into data on functional limitations assists in establishing the basis for an ergonomic system concerning disabled consumers.

The underlying premises for such a systm is that a chronic condition which causes a limitation of activity can best be described in tems of some combination of specific functional limitations. Despite the variety of possible conditions, the variety of functional limitations arising from these conditions is concise.

Following is a list of functional limitations derived from similar ergonomic systems published by the U.S. Department of Housing and Urban Development and the U.S. Department of Education (Mueller, 1979; Schroeder, 19 9):

* Difficulty in Interpreting Information--Impaired ability to read, reason and/or understand spoken or written information.

* Limitation of Sight--Difficulty reading newspaper print with eyeglasses, legal blindness and vision field defects of 10 percent or less.

* Total Blindness--Inability to receive visual information.

* Limitation of Hearing--Difficulty in understanding usable speech with or without amplification.

* Total Deafness--Inability to receive auditory information.

* Limitation of Speech--Capability of only slow or indistinct speech or nonverbal communication.

* Susceptibility to Fainting, Dizziness or Seizures--Spontaneous or inducible fainting, dizziness or seizures.

* Incoordination--Lack of control in placing or directing extremities and spasticity.

* Limitation of Stamina--Shortness of breath and.or abnormal elevation of blood pressure due to mild exercise.

* Limitation of Head Movement--Difficulty [TABULAR DATA OMITTED]

in looking up, down and/or to sides.

* Limitation of Sensation--Impaired nerve reception (heat, touch, pain, pressure) in various parts of the body.

* Difficulty in Lifting and Reaching with Arms--Impaired mobility, range of motion and/or strength in upper extremities.

* Difficulty in Handling and Fingering--Impaired mobility, range of motion and/or strength in hands.

* Inability to Use Upper Extremities--Complete paralysis, severe incoordination or absence of upper extremities.

* Difficulty in Sitting--Lack of strength, range of motion and/or trunk control in bending, turning or balance.

* Difficulty in Using Lower Extremities--Slowness of gait, impaired ability to kneel, rise, walk, stand, and/or climb stairs.

* Poor Balance--Difficulty in maintaining balance, whether standing or moving.

As indicated above, people reporting an "activity limitation" resulting from a chronic condition are considered as a group under each functional limitation which may result from that condition. By adding the populations of all chronic conditions causing a given limitation, an estimate of the total number of people experiencing that limitation is derived. This combined data provides the product designer, manufacturer or developer with a clearer estimate of the population of disabled consumers who might be affected by a given design feature and thus facilitate design decisions to suit the needs of this group.

Data on each of the above limitations was compiled from the NHIS survey, including breakdowns by age and sex. This data is presented in Table 2.

For the information in this table to be useful, it should be remembered that some chronic conditions, such as cerebral palsy, may result in more than one functional limitation. Therefore, people reporting an activity limitation due to this condition are listed more than once. Since some people experience multiple limitations, it would be misleading to total the populations listed as it would lead to multiple counting of individuals. Additionally, some limitations commonly occur with others (e.g., people with limitations of speech may also have limitations in interpreting information and/or limitations of hearing). About 73 percent of all totally blind people report other limitations, as do 71 percent of people with paralysis of the extremities (LaPlante, 1988).


Through interpretation of data from recent surveys of people with disabilities, this report presents demographic data which may prove vital to effective marketing strategies and product planning. In addition, this report establishes a framework of functional limitations around which ergonomic data will be developed and presented.

Future reports will focus on the ergonomics of the disabled consumer and will described the implications of each functional limitation for product design, specific features of product design which directly effect usability for people experiencing each functional limitation, and suggestions for overcoming barriers to universal design.

The Rehabilitation Engineering Center at the National Rehabilitation Hospital operates under a cooperative agreement with the National Rehabilitation Hospital and the National Institute on Disability and Rehabilitation Research, U.S. Departmjent of Education, Grant Number H133E80016.


[1] Bowe, F. U.S. Census and Disabled Adults, University of Arkansas, April 1984.

[2] Cherry, L. and Cherry, R. "New Hope for the Disabled," New York Times, February 5, 1984.

[3] DeJong, G. "Number of Adults with Severe Disabilities has Grown," Business & Health, March 1987.

[4] Farmer, M. "Redefining and Rebuilding American Life," The Marketing Institute, January 1989.

[5] LaPlante, M. "Data on Disability from the National Health Interview Survey, 1983-1985." An InfoUse Report, Washington, DC: National Institute on Disability and Rehabilitation Research, 1988.

[6] LaPlante, M. Disability Risks of Chronic Illness and Impairment, San Francisco, California: University of California, June 1988.

[7] Mueller, J. Designing for Functional Limitations, George Washington University Rehabilitation Research and Training Center, Washington, DC: U.S. Department of Education, 1979.

[8] Office of Technology Assessment. Market for Wheelchairs, Washington, DC: U.S. Government Printing Office, 1984.

[9] Ringwald, E. "On the Eve of Universal Design," Home Magazine, Volume 34, Number 10, 1988.

[10] Schroeder, S., et al. Access to the Built Environment: A Review of the Literature, Washington, DC: U.S. Department of Housing and Urban Development, Office of Policy Development and Research, April 1979.

[11] Stolov, W. C., M.D., Clowers, and Michael R., Ph.D. Handbook of Severe Disability, Washington, DC: U.S. Department of Education, Rehabilitation Services Administration, 1981.

[12] "Top U.S. National Advertisers," Advertising Age, September 1981.

[13] U.S. Bureau of the Census, Disability, Functional Limitation, and Health Insurance Coverage: 1984-1985, Current Population Reports, Series P-70, Washington, DC: U.S. Government Printing Office, 1986.

[14] U.S. Commission on Civil Rights. Accommodating the Spectrum of People with Disabilities, Washington, DC: 1983.

[15] Wiesel, Feffer, Rothman. Industrial Low Back Pain, Charlottesville, Virginia: The Michie Company, 1985.

Mr. Mueller is consultant to the National Rehabilitation Hospital, Washington, D.C., and President of J.L. Mueller, Inc, an Alexandra, Virginia, based consulting firm on disability management.
COPYRIGHT 1990 U.S. Rehabilitation Services Administration
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Author:Mueller, James
Publication:American Rehabilitation
Date:Jun 22, 1990
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