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Do you know how and why human factors are a very important part of designing universally for EVERYONE? IF human-factored, products are usable in spite of individual differences. Man-machine systems are engineered to ‘fit their users like a glove.’

Mission No. 4 will help you to understand:

  1. The importance accounting for individual human differences when designing products and environments to be universally-usable;

  2. The roles that anthropometrics and ergonomics play in human-factored designs of products and man-machine systems FOR ALL.


Before we get any deeper, let's consider a current human factors issue that you or your younger sisters or brothers may have experienced. If not resolved, SOMEONE may be very concerned about your “achey-breaky” backs!

TV sound byte: Who says that kids never do homework anymore?! If not, why are some elementary school students getting all bent over and walking around like they need a cane?! Experts have found the source of the problem: That innocent, perhaps cute or ‘macho'-looking, expensive, and often 'lost’ or forgotten somewhere after school, BOOKPACK!

Yes, school children whose bones and muscles have not yet matured, may be carrying way too much weight in their backpacks every morning and after school. Have you seen or heard any Public Service Announcements that give tips on weight limits and organizing book bags to avoid permanent injury to young musculo-skeletal systems?

WORD BANK: Human factors, posture, musculo-skeletal system, anthropometric standards, ergonomic, bio-mechanics, man-machine systems, usability testing, workplace design, ambidextrous, and… (list any others that you find you need to clarify in the dictionary or group discussion).

Three kids with backpacks sitting on a bench
Which pack looks LEAST likely to cause back injury to one of these young models when fully loaded with books, and why NOT? Have YOU read any good book bag labels lately? Photo credit: Target Stores.

Book bags and backpacks should be ergonomically designed, with instructions either sewn-in or on hang-tags. They should offer wide, padded straps or alternate attachments for the best pack height and angle, based on the child's height and weight. The one-strap, 'off the shoulder' look may be COOL, but TWO straps are needed to spread the load across BOTH shoulders.

Backpacks should be large enough to spread and balance the contents, but no wider than the child's shoulders or longer than the distance from the user’s shoulder to waist. One solution to overweight book bags is the roller pack, with wheels and a pull-out handle like the carry-on bags that fit in airplane overhead bins. If the tow-able pack isn't 'right,' the following hints for bookpack loading could save the back of a student YOU know!

Most important, the total weight of the loaded bag should be only 10-15% of the user's weight, depending on their strength and physical fitness. Distribute the load so that one-third rests on the shoulders, and the other two-thirds are supported by the hips. Heavy books go at the bottom, close to the spine and no lower than the waist. Finally, place smaller, crushable items like gym shorts or snacks on top, easy to reach in a hurry.

Two final checks: 1) While wearing the fully-loaded bag, the user should be able to stand straight at a resting posture withOUT effort. If the shoulders and spine obviously are OUT of their natural positions (e. g. leaning forward), START UNloading! 2) Heavy, bulging bags are more likely to cause a young person to fall since offset extra weight throws off their center of gravity.

Quotable Quote: Universal Design is not a trend, but an enduring design approach that assumes that the range of human ability is ORDINARY, not 'special' (Ostroff, 2002).


The reasons for human-factored design become obvious when we use products that don't fit the body—perhaps students’ bookpacks. First, a little discomfort, then over time the body may adapt negatively to a posture or movement that violates good body mechanics. Finally, the body screams, I can't stand the pain! (and heads for the doctor's office).

Another example: The labels on some clothing used to read, 'One size fits all.' Today, they say, 'One size fits MOST.' Why? Because many larger- OR smaller-than-average folks returned ‘fits all’ items, complaining that the labels were FALSE! Where would your self esteem go if something that said it would fit everyone, was WAY TOO SMALL or WAY TOO BIG—especially a non-returnable gift from a friend?!

Designers of spaces for living and working need to know about the intended users of those areas AND the furnishings. People’s physical characteristics (size, height, hearing and vision senses) vary widely. Human mental capacities and skills, plus emotional states also differ. As our bodies change with age, OTHER differences appear.

Whether a question of wearable products that fit their users OR workers doing repetitive tasks for hours on UNadjustable machines, human differences DO affect design--and vice versa. That's why knowing about anthropometrics and ergonomics is a GOOD THING!


Did you know that the “creative” writing styles of some left-handed people are caused by trying to avoid smudges as their palms move right over what they just wrote? If you haven’t experienced being a 'Southpaw,’ casually survey several Lefties to discover the inconveniences (even dangers) that they face in a Right-Handed World. Meanwhile, a few questions about that one little/big human difference.

  1. Multiple choice: In addition to inconvenience, being left-handed is:
    1. Maybe a small disability
    2. A mark of distinction
    3. No big deal
  2. T or F: Seven U. S. Presidents (including Reagan, the first George Bush, and Clinton) have been left-handed.

  3. T or F: Left-handed people make up less than 10% of the world's population.

  4. T or F: Southpaws must either use cutting shears in their right hands OR use them left-handed and bear the pain (It can hurt!).

Right-handed items that are difficult to use left-handed include baseball mitts, hockey sticks, and some shears. Circular saws and other tools with handles to the right may be dangerous to Lefties who are not ambidextrous (switch-hitters).

Left-handed youth often have to get ‘special ‘products OR adapt to things designed for the majority hand. For example: the controls of most cars must be operated by the RIGHT hand. In-stock (vs. special order) home entry door handles and tub and shower controls usually are installed on the RIGHT to fit 90%+ of the people who grab them. For more LEFT-WING info, CLICK on one or both websites below:

Famous Lefthanders
Southpaw Frustrations

Food For Thought: Are all or most student desks at your school or library comfortably usable by both left- and right-hand writers withOUT changes? If not, how many left-handed desks or chairs do most class- or assembly rooms offer? Are they easy to find when needed? OR, do they use UNIVERSAL work surfaces that are either-handed?


The ANTHRO- prefix usually applies to a body, while metric refers to measurement. The science of anthropometrics uses data on human dimensions and ranges of motion (how far various body parts can move). Researchers usually measure subjects from a particular group (e.g., older adult females), then calculate the averages. They also study differences between groups (e.g., comparing young women to very old ones).

The anthropometric drawing below lists the body dimensions that interior designers use most often. Another chart might show the highest and lowest points that subjects can reach from both standing or sitting positions, in percentiles by age and sex. Anthropometric measurements also are used to develop standards for human clearances and maneuvering space between pieces of furniture or equipment.

'Anthro' data provide the bases for the human scale standards included in the building regulations and product design guidelines that designers use. Steinfeld (2002) predicted that standardized data collection methods, plus larger and more diverse groups of subjects (including children, plus people with NONmobility disabilities) mean that more and better anthropometric standards will be in our futures.

Anthropometric (body) measurements
Anthropometric (body) measurements of most use to designers of interior spaces (Panero, J. and Zelnik, M., 1979, p. 30).

The Anthro LINEUP

Do you wonder whether (adequate) anthro standards are available for adolescent males and females? Next time you're in class or hangin' with a group, have at least 10 teens stand side-by-side, from shortest to tallest, against a wall. Notice the physical differences in arm, leg, and trunk lengths—even among same-sex and similar-height Dudes and Divas. You’ll see the wide variations in growth rates and over-the-summer spurts that Mom FINALLY notices when shopping for new (destructed) jeans for school.

Among young teens, some girls grow faster and taller than most of the boys. But most guys catch up and pass them in a year or two to become Long-Tall, Terrific Teens. (The Voice of Experience: Going from eighth grade (where three of us girls were taller than ALL the boys) to High School was a BIG THRILL because suddenly, we had to look UP!


If you've heard of ergonomics, the words, “work” and “person-machine fit,” probably were mentioned too. Ergonomic (biomechanic) designs consider the person, the job, how long it takes, strength required to do it, AND the equipment and operating processes (man-machine systems) involved. In the case of ergonomically-designed sports apparel and equipment, the JOB is to have fun (AND win)!

Based on anthropometric standards, ergonomic products are shaped to fit the body's contours and adjust to fit different heights and limb lengths. They’re comfortable and easy to use, even if you have very short arms or really long legs. Here's a 5-minute ergonomic pre-test based on a quiz by Humantech Consultants in Occupational Ergonomics. If you won't remember your answers, either print this screen or use a slip of paper to record them.

  1. True or False? Desks and work stations used by different classes in a school or multiple shifts of employees during a 24-hour work day should have adjustability features.

  2. T or F Most computer keyboards and workstation keyboard trays are manufactured at the ‘correct’ angle and height for most data input specialists, so don't need to be adjustable.

  3. The best place for the computer-user’s mouse or touchpad (regardless of whether or NOT they are integral [built-in]) is:

    1. Between the keyboard/pad and screen, on the same level
    2. Beside keyboard/pad on same side as user’s dominant (writing) hand
    3. Next to and level with bottom of the computer monitor/screen
    4. Near the keyboard/pad at height that WILL NOT require user’s wrists to bend UPward

  4. Not counting 15-minute breaks, how often should the workstation, computer, OR seat be adjusted during a four-hour shift (e.g., all morning, all afternoon)?

    1. Never: The majority of computer work station parts are NOT adjustable
    2. Every 30 minutes
    3. Every few hours, when s/he feels the need for a muscle break

  5. When typing on a desktop computer, the monitor (screen) should be placed:

    1. To the left or right of your keypad, depending on whether user is a Leftie or a Right-hander
    2. Depends on user’s vision and the sizes of the font and screen surface
    3. Wherever the user will NOT get a ‘crick’ in her/his neck after 4+ hours of fixed staring.
    4. Under a glare-free ‘window’ built into work surface, and tilted for easy viewing without eye strain

  6. (How) would your answers to Questions 3-5 change IF the computer was a notebook/laptop or a 'radical' new system whose parts and configuration are different from any previous computers you've used?


Past environmental designers often expected consumer-users to ADAPT to their creations. Later, the major complaint of office workers (especially those who used computers for more than four hours a day) was back problems that resulted from INadequate task seating.

Employees’ back problems, plus Carpal Tunnel Syndrome (CTS) have cost employers and the government’s Workers’ Compensation program millions of dollars each year in lost work time and medical treatments. As a result, new ergonomic regulations have arrived at the workplace!

CTS (also called tendonitis) affects workers who input computer data for hours with hands at the wrong angle or height, and lacking proper support. The “cure” may be to add a hand rest that keeps wrists level, NOT bent up OR down, plus user exercise breaks to strengthen the wrists. OR: The keypad or its tray may be too high or too low, and needs to be adjusted by an ergonomist or occupational health specialist.

Ergonomic and adjustable computer workplace design is relatively new within the arena of man-machine systems (Mueller, 1995). Ergonomic designers now consider the intended users FIRST as they create products that fit or adapt to a range of sizes and shapes. The results are much better than earlier designs for special needs that look different and stigmatize their users (Ostroff, 2002).

The U. S. Occupational Safety and Health Administration (OSHA) oversees hazardous jobs such as office occupations. They recommend ergonomically-designed task seating, plus re-designed tasks to improve workers’ posture and body mechanics.

Since the Nineties, voluntary international standards (ISO) for office furnishings have guided the design of ergonomic seating. To see if it's an older, nonstandard chair still at work, look under the seat for the ISO label. The task seating collage below shows a variety of ergonomic and universal office seating.

The "Chool" seat. Credit: Levenger CatalogMambo Stool" - the universally designed award-winning seat"Aeron Chair", Credit: Herman Miller
The "Freedom Chair" adds neck support to adjustable set and back height and tilt. Credit: Levenger"Poetry in Motion" The swopper moves with you and keeps your posture correct. Credit: Herrington Catalog.

Human differences also affect the design of student desks, work tables, and chairs that may seat different users every hour of the school/work day. School district budgets may dictate that one basic design and size must 'do.' But ergonomically-designed seating and adjustable work surfaces will be far more comfortable for far more students.

Ergonomically designed tables
Ergonomic, height-adjustable worksurfaces. Fit more people, more comfortably w/o making a BIG DEAL Wall desk under shelf light and framed corkboard is economically height adjustable for infrequent changes.
Right Height table adjuster.
Credit: Dynamic Living

The Scooter table“Grow with me” adjustable desk
The Scooter, by Herman Miller, rolls right over the user’s lap, with its height- and tilt-adjustable, protected writing surface. Credit: Levenger catalog “Grow with me” set has height-adjustable desk in boomerang shape to get closer to your work. Full swivel, height-adjustable, rolling stool grows from elementary school to adulthood. Credit: Levenger catalog

Quotable Quote: In the workplace, tangible results of UD can include reduced human errors, increased productivity, fewer sick days, and lower employee turnover (Vanderheiden, 1999).

Ergonomic designing is not limited to man-machine systems. Many low-cost gadgets that help with daily living are also human-factored. Large-print playing cards and automatic card shufflers allow older adults with low vision and stiff fingers to keep playing bridge or poker as long as possible. For short OR tall people and those with stiff joints, 'robotic' long-arm extenders pick things up from the floor AND off top shelves safely, without bending or reaching. In addition to those below, see other examples in the Lesson 2 sections on aging safely and independently.


Have you ever asked, “Why doesn’t this work better? Why can’t they make this easier?” World Usability Day (WUD) is sponsored by the Usability Professionals’ Association, an international group of specialists who evaluate and design products that are easy to learn and use.

On November 3 in 2005, the 36-hour WUD started with breakfast in New Zealand and ended about 10 p.m. in San Francisco, California at the opening reception for a major conference. That long day promoted the value of usability engineering, user-centered design, and every user’s responsibility to ask for things that work better.

Like user-centered design, usability tests have NOT been common practice in past U. S. product development. Rather than the typical 10 test subjects or only the models demonstrating products in commercial advertisements, usability testing requires a full understanding of (all) REAL USERS (Story & Mueller, 2003).

One potential result of the Rehabilitation Act Amendments of 1998 is that usability tests will become the RULE (NOT the exception) in the 21st Century. Section 508 of the Amendments states that electronic and information technology (EIT) and services bought by the federal government must be usable by people with disabilities.

A guy listening up with headphones Section 508 requires EIT performance standards in addition to technical specifications for product design and production. Laboratory product tests alone won't be enough to meet the requirement—real user-testers with limitations must be involved. Previous tests with subjects of varied ages and abilities found NO substitute for direct input from users with physical, sensory, and cognitive disabilities (Story & Mueller, 2003).

Have you noticed the post-1998 “rash” of new user-friendly features on computers and electronics? The increased EIT industry efforts to comply with Section 508 reveal the power of economic incentives (IF they want to sell EIT to our HUGE government). The consumer product industries are likely to follow suit--soon. Thus with each new day, we'll be more likely to find both the 'U' and 'I' in UnIversal Design.


  1. Designer Shoe Human-Factored, Sustainable Design: The Footprint above extends ‘Hippie Chic’ to a new urban consumer (from the description of this IDEA gold award design in Business Week, July 2003). Famous for their comfort and thick rubber soles, Birkenstock worked with fuseproject design [sic] to create 35 new shoe models that use both traditional and new RECYCLABLE materials. Urban AND Rural Hipsters TAKE NOTE!

    The annual Industrial Design Excellence Awards are sponsored by Business Week and juried by the Industrial Design Society of America (IDSA). At www.idsa.org, see the 2004 and 2005 IDEA showcases of winners plus current industrial design news and related hot links.

    From the ’04 or ’05 IDEA winners, select the five that you think best demonstrate human-factored, universal design (gotta be BOTH!). Share your choices and reasons with friends, family, and your class or after-school group.

  2. Human-factored, Universal Product Scavenger Hunt: First, to save YOUR Footprints for later steps, consult the AWESOME UD website developed by the Iowa State University Extension Service.

    Select up to three examples of human-factored household products (that you haven’t already met) from the site’s HUGE list of products. Print an image of each example with at least a paragraph of its description.

    LINK: http://www.iastate.edu/extension

    Step Two: Get together with classmates or group members to share, then make a list of 10-15 examples to include in an Ergo-UD Scavenger Hunt. Don’t worry, YOU won’t have to take them from the homes or stores where you find them.

    Combine images of each item into a VISUAL SEARCH LIST of the products and manufacturers’ names. Make copies of the list for each teen to SHOW at the places “searched.”

    Step Three: Following the usual Scavenger Hunt rules, choose partners, map the designated neighborhoods, and specify time allowed (an evening or a whole weekend—YOU choose). Be prepared to explain WHY and for whom the products are EXCELLENT (using UD Principles’ terms….flexible use, etc.).     HAVE A GOOD TIME!

    Have you played one of the ”Sims” games (e.g., "Sims in the Urbz” or “Sim City 3000”)? The Sims Online Trading Spaces Expansion Pack allows wanna-be decorators to look like popular TS personalities. “Enter any dwelling you choose and give it a face lift while the owner is away. It's NOT vandalism; it's ART! Besides, it's only a game, RIGHT?!!” (Game Informer, 2003).

    Rather than the Sims, maybe you could try Empathic-Simulation Exercises (ESE) if your Guide thinks you’re Right for them. The exercises can make you aware of and sensitive to human differences and commonalities (Pastalan, 1972). The experience also demonstrates the IMPACT OF THE DESIGNED ENVIRONMENT on various levels of human ability.

    The empathic “sims” allow participants to get a TINY taste of what people with disabilities experience on a daily basis, BUT DO NOT show what it's like to HAVE that specific limitation. The authorities on disability are those who live with such limits. Your Guides have the ESE instructions and can arrange for your group to complete the simulation exercises using Guest-Experts with disabilities to observe, comment, and “de-brief” you afterward.

whellchair access image of man outside bathroom

ONE size (door) does NOT fit ALL!
Good thing I can get into the bathroom on crutches, or I'd be showering with a hose (outdoors)!

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