Category Archives: affordances

Don Norman’s 10 Rules for Successful Products

The embedded video below is a one-hour talk given by usability guru and cognitive psychologist Don Norman.  He discusses his 10 Rules for Successful Products.  Factoid: Did you know that his landmark book, “The Design of Everyday Things” was originally called, “The Psychology of Everyday Things“?  I guess psychology was a dirty word back then.


Glass Shower Doors

I found this story about shattering shower doors first on The Consumerist blog and then the original by the author, Bob Sullivan at MSNBC (quoted below).

I had just finished showering and turned off the water. Soaking wet, I did what millions of Americans do every day — I reached for my snazzy sliding glass shower door. Seconds later, glass was raining down on me. The door had failed somehow and exploded into a million little pieces. The sound was hideous, something between nails on a chalkboard and a torrential downpour…

At first it sounds like an engineering issue: tempered glass shatters easily (although thank goodness it was tempered!) So, the trade-off is to have glass that breaks more easily, but is safer when it does break. The human factors issue that stood out to me appeared in the advice given by Kohler:

Do not use the shower door towel bars as a safety grab bar or as a lift assist when getting in and out of the bath, or lowering and lifting off a toilet. (MSNBC)

Do not put any weight on the shower door grab bar. (Consumerist)

So, don’t grab the grab bar, ya’ll.

*Photo credit Eqqman*

The Human Factors of Rock Climbing – A matter of life and death

A tragedy occurred last week in West Virginia where a rock climber died apparently due to a human factors issue with her gear. This text comes from a commenter on

The climber was Karen Feher from Midlothian Va. She climbed to the anchor of Rico Suave and clipped in direct. Her setup: She had two thin dyneema slings girth hitched to her harness. At the end of each sling was a locking carabiner held in place with a rubber Petzl keeper…She clipped a locker to each bolt and probably called off belay. I’m unclear if she was going to rappel or lower. It doesn’t matter. She fell to the ground.

The day after the accident a local climber named Craig (last name?) climbed to the anchor and found a locker on each bolt with a Petzl String still affixed to each one. Both Petzl strings were torn on the side.

Let me give a little background on the gear so you can understand what seems to have happened:

Climbers can affix themselves to the wall with equipment that has carabiners on both ends. This allows them to clip themselves to one side and clip the other to the wall. These can come in different varieties, and two types are illustrated below.

The first type consists of a sewn sling between the two carabiners. It is sewn tightly in multiple places to make sure that it holds tightly to the two carabiners.

A "quickdraw" with two carabiners
Notice the larger and smaller holes in each end. One holds a carabiner loosely to the rock while the other holds a carabiner more tightly on the rope end.

Notice on one side it is sewn so the carabiner hangs loosely and on the other side it is sewn tightly, so that it holds the carabiner almost immobile. The reason for this is to allow the side connected to the wall to swing freely as the rope moves, which keeps the rope movement from jarring or upsetting protection put into the rock. The other end that is connected to the rope keeps the carabiner from moving around and possibly turning sideways.

The second type (below) consists of a nylon sling doubled over between the carabiners. The benefit of this kind of sling is that it can be changed in length – by doubling and tripling it, it can either be 4′ long, 2′ long, or just a foot long. However, notice both sides are the same. The benefit of having one loose side and one tight side does not exist here. Incidentally, this is the type of sling I use almost exclusively.

A simple loop connects the two carabiners
A simple loop connects the two carabiners
The sling has now been doubled over to shorten it

There is one way to turn the second type of sling into an approximation of the first type: a rubber band. Not only can you do this with a plain rubber band, there are some specifically sold for this purpose.

The rubber band holds the rope end tight while allowing the other end to swing freely
Again, rope holds one end, this time with sling not doubled over

The problem with this solution lies in the changes to visibility and function that the rubber bands can have when the slings are doubled-over incorrectly.  Click here for a video explaining what can go wrong.

Essentially, the sling can become almost invisibly connected ONLY by the rubber band. I am sure no one would like to think of hanging 100 feet from the ground by a grocery store rubber band.

The additional component to the tragedy that prompted this post is that both of her slings were attached only by the rubber band. Climbers build redundancy into their systems to prevent accidents like this, but here both failed.

Exit Signs Across Cultures has a nice article on the difference between U.S. exit signs and the rest of the world, as well as a nice history of the evolution of the symbols.  Here is an excerpt to get you interested:

The text-based American exit sign has its origins in the 1911 Triangle Shirtwaist Fire, a blaze in a downtown Manhattan garment factory that killed 146 workers. Although signage was not primarily to blame for those fatalities—many factory doors were bolted shut in an effort to keep employees from slipping out—the exits were not clearly marked. That massive loss of life spurred the National Fire Protection Association, which had been founded in 1896 by insurance companies to develop protocols for property preservation, to take up what it called “life safety”: the business of getting people out of burning buildings intact. In the 1930s and ’40s, the NFPA developed criteria for emergency-exit signage, evaluating contrast levels and testing different sizes and stroke widths for lettering, eventually publishing standards that were adopted by state and local governments across the land.

Dissecting the iPad’s User Interface

This Flickr image set does a nice job of pointing out the unique UI elements of the iPad.  Much of the interface is adapted from Apple’s extensive work on the iPhone but there are several unique elements.

Say what you will about Apple (positive or negative) but their tight reign on software and hardware and extreme focus on details really shows.

On a separate note, while I probably won’t be getting an iPad, the use cases illustrated in the keynote video are very compelling (e.g., imagine using this as a data collection device in the field).  I just can’t see myself lugging around a third device.

[Via TechCrunch]

This does not bode well for the on-device user experience…

Gizmodo reviewed the Nook e-book reader from Barnes & Noble. Unfortunately (for B&N), the process of opening the package was so cumbersome, most of the review dwells on that aspect:

In other words, the Nook packaging actually necessitates these lengthy instructions, as ridiculous as they are in their own right. Somehow, Barnes & Noble invented a box that’s every bit as complicated as their product.

Here is the instruction sheet to OPEN the package (via a 7 step process):

Instructions to open the Nook package. Note the toll-free number to call if you have trouble unpacking!! (from Gizmodo)

Another reviewer has even more negative things to say about the package:

Once the sleeve comes off, you are presented with what amounts to a clear acrylic puzzle box: pull of the plastic seal, pop the two parts of the box apart, and then release the nook from the death grip of the clear plastic holster it’s cradled in. I’ll admit, I was getting a little frustrated during the unwrapping, and I couldn’t help but be thankful I wasn’t filming it. Compared to the easy paper zip-cord on the Kindle’s packaging, unboxing the nook would be embarrassing to do live — especially for someone as klutzy as me.

Environmental Controls: Spotlight on Volvo

I rode in a colleague’s new Volvo the other day and I love the environmental controls. The button lights up when active, showing where the airflow is going. Notice how the fan speed control is integrated into air direction display so they each add information to the other.

Compare to the older Volvo buttons, which had a similar theme but not quite as pleasing. It also lacks the integration of the fan speed.

Vent controls on an older model Volvo

And Ford:

New Ford vent controls

Last, the controls I just had on a rented Toyota Corolla in Las Vegas:

New Toyota vent controls

In this Toyota, you press the “mode” button and it cycles through an LCD to show you where the air will flow. I found it hard to see and I had to infer that “mode” was the right button. I was never able to figure out these controls while driving and had to ask my passenger to work them for me.*

In sum, I like that the Volvo buttons allow for all combination (feet/torso, feet/defroster, torso/defroster). This is something I always wanted in my previous cars. I also rate it high on the “emotional” side of design.. it looks great!

*As a side note, the entire frame for this interface glows light blue, thus ruining my night vision and was tiring to have in the periphery while driving. I prefer the all red dashboard of my 2003.

Encouraging Sanitary Behavior at the Urinal

From reader Scot M. comes this NPR story. To encourage proper “aiming” at urinals, some places are now placing images of bugs so that men have something to aim toward. I’ve seen these at Schiphol Airport as well as my local grocery store bathroom (and I live in a tiny town).

Keiboom in Amsterdam says the original fly idea was proposed almost 20 years ago by Dutch maintenance man Jos Van Bedoff, who had served in the Dutch army in the 1960s. As a soldier he noticed that someone had put small, discrete red dots in the barracks urinals, which dramatically cut back on “misdirected flow.”

Two decades later, he proposed to the airport board of directors that the dots be turned into etched flies. According to Keiboom, Van Bedoff decided that guys want to directly aim at an animal they can immobilize. The ability to use one’s natural gifts and achieve victory over the foe while standing is the key, he explained. Guys, he felt, can always beat flies. That’s why flies are so satisfying.

Dangers of Automatic Windows

Recently I posted on some potential human factors problems caused by Toyota’s design of their floor mats. For this post, I would like to compliment Toyota on their automatic power windows. The windows can be lowered fully and automatically by one quick press on the button. However, to be raised, the lever on the button must be continuously raised until the window closes.

This is good for two reasons:

  • if it raised automatically, people and pets could be easily hurt by the closing window.
  • if the buttons were press-only (or a toggle), a knee, hand, paw, or other object can cause the window to close on something unintentionally.

I did not appreciate these functions until operating a Honda window recently that closed with one upward pull of the button, when I did not intend to close it.

Consumer Reports recently published an article on this design problem. There are many injuries each year from automatically closing windows and some deaths, usually children. There is new legislation to require that windows auto-reverse when they encounter an object. Examples of the two types of switches are shown below.