By the end of this lesson, you should be able to:

2. Discuss the importance of using measurements of humans in designing human interfaces.

3. Perform anthropometric experiments.

has been defined as 

Historically, products have been designed out of chunks of metal, wood, plastic, and other materials. Their shape, size, and features may be a product of the machining environment.

Look at this typical design for a utility knife:

Compare that design to this "ergonomic utility knife":

The second knife does have features that take into account the typical user's hand size, shape, and movements, unlike the first design. Yet, some may be unconvinced that the second design is an improvement. For example, it is cumbersome to hold inverted. What do you think?
 

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You are likely reading this text off a computer monitor right now, and using a mouse and a keyboard. But does the layout of your workstation put any extra and unnecessary stress on your wrists, eyes, or back? Do your habits of using these tools heighten the risk of physical problems? For suggestions on computer workstation habits to overcome some of these common problems, please see the Centers for Disease Control's page on Computer Workstation Ergonomics at (required visit):
www.cdc.gov/od/ohs/Ergonomics/compergo.htm

While there, check out the links on their Ergonomics Home Page.

In order to better design products for humans, it may be necessary to learn about human sizes and abilities.

These measurements are usually made of a particular sample of the population, and often separated on the basis of sex and age. Typical anthropometric measurements include standing stature, weight, distance between eyes, and circumference around waist. However, sensory abilities may also be measured, such as hearing ability, sight, and the ability to sense touch.

Try perform this experiment on a friend, with a witness so your friend does not later accuse you of lying.

1. Ask you friend to stand or sit with their back to you. 

2. Tell them that you are going to lightly touch them on the back either with one index finger, or with two index fingers, and they are to say "one" or "two." (This works through the shirt.)

3. Hold your index finger so they are touching and parallel to each other. Gently tap your friend's back, making sure both finger tips touch the back at the same time. (Your friend should say "one" or "two.")
 

 
4. Repeat this with a slightly increasing distance between your fingers and at different sights on the back, but always use two fingers.

 
5. What did your friend say? What did you learn about their ability to sense touch on their back?

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Other anthropometric measurements are made of abilities, such as lifting strength, jump reach, and grip strength. But should designers use anthropometric data in creating or adapting product designs?

Perform Experiment 2 following the procedure described below, and in the optional video:

 Windows Media Video, 321Kb

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1. Stand with your arms at your side.

2. Bend your right elbow at a 90-degree angle. Your right palm should be facing left, and your right wrist should be straight.
 

Right wrist straight

 
3. Place two fingers from your left hand against your right palm; keeping your right wrist straight, make a fist around these fingers and squeeze hard as a test of your grip strength. Release.

Right wrist straight

Gee, you're pretty strong, aren't you?

4. Now, repeat the procedure, but this time bend your right wrist at a sharp angle (so your palm faces your abdomen.)

Right wrist at a near-90-degree angle
 

Grip strength with a bent wrist

5. Was your grip strength different at this position? Have you ever tried to complete a task that was much more stressful than normal because your body was twisted or extended in an odd way? What mistakes might designers make by looking at tabled values of anthropometrics? What mistakes might users make concerning their own estimates of their abilities? (These are rhetorical questions, but feel free to add answers, comments, or other questions on the subject to the discussion board forum for this module.)