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LESSON 4: HUMAN FACTORS: WILL ONE SIZE FIT MOST?!
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 and man-machine systems fit their users' like a glove.
Mission No. 3 will help you to understand:1
- The importance accounting for individual human differences when designing products and environments that will be universally-usable;
- The roles that anthropometrics and ergonomics play in human factored designs of products and man-machine systems FOR ALL.
THE BACKPACK OVERLOAD MYSTERY UNRAVELS
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 it's not been resolved, your parents may be very concerned. Look out below!
TV sound byte: Who says that kids never do homework anymore?! If not, why are elementary school children getting all bent over and walking around like they need canes?! Experts have found the source of the problem: That innocent, perhaps very 'cute' or 'macho' -looking, probably way too high-priced, and often 'lost or forgotten' some place else right after school, BACKPACK!
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 television or radio Public Service Announcements giving tips on weight limits and organizing book bags to avoid permanent injury to young musculo-skeletal systems?
WORD BANK (in order of appearance and bolded in the lesson): Human factors, posture, anthropometric standards, ergonomic, bio-mechanics, man-machine systems, usability testing, workplace design, ambidextrous
School book bags and backpacks should be ergonomically designed, with instructions either sewn-in or on 'hang-tags.' They should offer a choice of straps or alternate attachments for the best height and angle, given the child's height and weight. The one-strap 'off the shoulder' look may be COOL, but both straps are needed to spread the load across both shoulders.
The bag should be large enough to spread items out, but no wider than the child's shoulders or longer than the distance from his or her shoulder to waist. One solution to overweight book bags is the backpack on wheels with pull-out handles like the carry-on bags that fit in airplane overhead bins. If the tow-able pack isn't 'right,' using the tips below to load a pack may save the back of a child you know.
Most important, the total weight of the loaded bag should no be more than 15% of the child's weight. Next, distribute the weight so that heavier books are at the bottom, no lower than the user' s waist and close to their spine. Heavy, bulging bags are more likely to cause a child to fall, since extra, offset weight throws off their center of gravity.
Finally, place smaller and crushable items like gym shorts or a snack at the top of the load, easy to reach in a hurry. Two final checks: The user should be able to stand straight in a resting posture without effort while wearing the fully-loaded bag. If the shoulders and spine are obviously out of their natural positions, start unloading!
Quotable Quote: Universal Design is not a trend, but an enduring design approach that assumes that therange of human ability is ordinary, not 'special.' (Ostroff, 2002).
THE HUMAN FACTORS RATIONALE
The most important reasons for human-factored design become obvious when you use products that don't fit the body—for example, the backpack. First, a little discomfort, then over time the body may adapt negatively to a posture or movement that violates good body mechanics. Finally, a body screams, I can't stand the pain any longer! (and heads for the doctor's office).
Another example: Years ago, wearable products carried labels that read, 'One size fits all.' Today, the labels say, 'One size fits MOST.' Why? Because many larger- or smaller-than-average folks returned items to stores, complaining that the labels' claims were FALSE! Where would your self esteem go if something that came in 'one size only' was way too small, or even way too big? Worse yet, if it was a non-returnable gift from a friend?!
Designers of spaces for living and working need to know a lot about the users for whom the areas are intended. People differ widely in physical characteristics such as size, height, strength, or the senses (especially hearing and vision). Human mental capacitiesand skills plus emotional states also vary. As our bodies change with age, other differences appear.
Whether it's a question of how wearable or other products 'fit' their users or whether diverse workers can do repetitive tasks for hours at UNadjustable machines, human differences DO affect design, and vice versa. That's why knowing a little about anthropometric and ergonomics is a GOOD THING!
Source: Division for Social Policy and Development of the United NationsANTHROPOMETRIC (HUMAN SCALE) STANDARDS
The anthro- prefix usually applies to a body, whether human or a gorilla, metrics relate 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 and study the differences.
The image above is an anthropometric drawing shows the body dimensions that space designers use most often. Such charts and tables may show the highest and lowest points that subjects can reach from both standing or sitting positions, in percentiles by age and sex.
'Anthro' data are the bases for the human scale standards included in the building regulations and product design guidelines that designers (must) use.Steinfeld (2002) notes thatstandardized data collection methods, plus larger and additional groups of subjects (e. g., children, plus persons with disabilities USING their wheelchairs) mean that the future holds more and better anthropometric standards.
The Anthro LINEUP
Do you wonder whether anthro standards for (pre-)adolescent males and females are available and adequate? Next time you're hangin' with a group, get 8-10 teens to stand side-by-side, from shortest to tallest. Notice the physical differences in arm, leg, and trunk lengths—even among same-sex and similar height divas and dudes. Both have wide variations in growth rates and over-the-summer spurts that Mom finally notices when shopping for new school jeans.
Among young teens, some girls grow faster and taller than many of the boys. But most boys catch up in a year or two and pass them to become Long-Tall, Terrific Teens. (The Voice of Experience speaks: Going from eighth grade, where three girls in our class were taller than ALL the boys, to High School was a Big Thrill because suddenly, we had to look UP!)
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Last Updated May 3, 2005
