Category Archives: affordances

When poor usability costs you your job?

You may have heard that an employee who managed “social media” for Chrysler accidentally posted on Chrysler’s twitter account about *ahem* poor driving in Chrysler’s home city of Detroit. Click here for the original story.

The guy who sent the tweet blames the program he used for multiple twitter accounts. The article calls it a “glitch,” which would not necessarily be usability, but it seems more likely to be a problem with understanding what account a tweet will come from when multiple accounts are accessible.

From the article on WXYZ:

Scott is convinced a software glitch on a program called Tweetdeck led to the tweet being sent out on the wrong account. He says he deleted the Chrysler account from the program, but somehow it still went out.

His attorney, Michael Dezsi, says Scott has a case.

“A simple web search shows a number of other users have encountered the same issues,” Dezsi said.

Action News made contact with a Tweetdeck spokesman via email about the claim.

“We are not familiar with the error you describe–tweets sent from a deleted account–but we normally would try to replicate it to make sure there is no problem on our end (although it sounds very unlikely that this is a TweetDeck issue). If you know the type of hardware, platform and TweetDeck version we could check further,” said Sam Mandel, Tweetdeck executive vice president of business operations.

People like Tweetdeck, though they admit the interface is complex.

This looks like another case where people feel more justified when the problem is a software bug or engineering glitch than when a usability problem caused the error.

Honesty Hurts (especially when design is poor)

I enjoy the mix of economics and psychology, which is why I am a faithful reader of the Freakanomics blog. Their recent podcast on “pain” started off with a good human-factors-related tale of the problematic design of a subway alarm system. I have included a link below to the podcast, but the quick overview is that there is an ear piercing alarm that is triggered by using the “emergency” exit, which is invariably used every day by someone wanting to get out faster than turnstiles permit.

The person breaking the rules has to hear the alarm for the shortest period of time and face no repercussions. The law abiding citizens waiting in line to exit get to listen to the alarm the longest.

Link to the podcast

Photo Credit Wavebreaker @ Flickr

Trashcan Affordances

The picture above shows the front and back of a trashcan designed to be lifted by machinery.

This past weekend I helped my parents start to clear their home for an upcoming move and filled this trashcan to capacity. I didn’t want my mother to have to haul it to the street, so I went to go do that before I left.

I looked at the front of the can and saw the metal bar (left picture). I looked at the can and saw the wheels were on the other side and thought “I guess I grab the bar so it tilts onto the wheels.” When I did it pretty much instantly tipped over and dumped out all of the items it contained (many of which weren’t in bags, since I knew it was dumped by a machine into the truck).

Because, of course, you should grab the handles at the top (right picture) and lean the can toward you on the wheels. But I saw the bar, so I did what you do with a bar and grabbed it. I learned two things: 1. I don’t know much about trashcans (lucky me?) and 2. Sometimes affordances are for non-humans… that bar was to be grabbed by the dumptruck machine, not me!

Online Map Readability: A Comparison

Justin O’Beirne presents an extremely thorough and interesting analysis of why Google Maps appear more readable than its competitors. I’ve noticed this as well. It’s one of the major reasons I still prefer Google Maps despite some very compelling features of Bing and Yahoo maps.

One visual trick that Google applies to maps is a localized de-cluttering around major cities.

This is made much more obvious when we view city labels by themselves:


Pull the push door
The picture above was taken from the Starbucks near the convention hotel for HFES 2010. Rich and I were walking in there at 6:30 a.m. when we saw a man exiting the doors, shaking them violently, and uttering curse words. We had to laugh when we saw what made him so angry – a push bar on the inside of the door with a sign that said “PULL.”

As we took the picture of the PULL sign, a woman came up behind us to exit. Trying to help her, Rich naturally reached out and pushed on the door.

Too standardized? – The problem of tube identification in hospitals

When it comes to efficiency, creating standard sizes and connections saves money, production efforts, and makes for easy substitution when one runs out of an object. For example, I was delighted that lid for one brand of pot perfectly fit my new frying pan. Unfortunately, there are times when we do not want parts of one object to fit another because it can encourage dangerous errors.

The New York Times ran a recent article on the similarity between the many tubes used in hospitals for different purposes. These purposes include:

  • Intravenous use
  • Inflating blood pressure cuffs
  • Feeding tubes

Obviously, very different materials pass through each of these tubes, and mixing one with another can be deadly. The article discusses several cases where food or air was passed into patient veins. The tubes entering the patient are often compatible with multiple sources of input, with no guard besides notoriously fallible human attention to prevent a mistake.

From the NYT article:

…the F.D.A. has issued three alerts to hospitals and manufacturers warning about tube mix-ups, the most recent of which was sent out last month after The Times began asking about the issue. Ms. Pratt said she persuaded one manufacturer, Viasys, to produce neonatal feeding tubes that are incompatible with other tubing. Viasys’s tubing is now used in Sharp’s neonatal intensive-care units, but they are expensive — $13 compared with $1.50 for regular tubes.“The regulators have been waiting for the manufacturers to come up with a solution,” Ms. Pratt said, “and the manufacturers won’t spend the money to design and produce something different until the regulators force them to. And now the international standards organization is taking forever to get the whole world onto the same page.”

Nancy Foster, vice president for quality and patient safety policy at the American Hospital Association, agreed, “These things are hard to change when you have to get so many different organizations to act in concert.”

Blogging APA Division 21: Maximizing Stimulus-Response Compatibility

Kim-Phuong L. Vu was this year’s winner of the Earl A. Allusi Award for early career achievement. Her presentation covered maximizing stimulus-response compatibility to optimize human performance.

Vu reported on her studies of people’s performance under different levels of stimulus-response compatibility. For example, high stimulus response compatibility occurs when a blinking button needs to be pressed. The blinking is the stimulus and the button press is the response. They become less compatible as the signal for pressing the button moves further from the button itself. In the worst case, a well learned response is reversed – imagine if moving your computer mouse to the right moved the cursor left. This would be terribly incompatible, but would be even worse if you were already well experienced with the mouse moving in a compatible manner.

Vu gave some great examples of how stimulus response compatibility is much more than common sense. In coal mining, the controls for a mine transport operate in one direction (a compatible one) going in to the mine and reverse when leaving. When controlling military drones visually (UAVs) or any remote controlled object, the input controls must be reversed when the machine is flying toward the controller. In my mouse example, it is not common sense for a mouse to work as it does — there is no universal compatibility that moving a mouse forward should move it upwards on the screen. Indeed, many flight input devices work in the opposite way, so that a forward movement makes the plane descend. This compatibility was learned, but nonetheless is disrupted when changed.

Dr. Vu is currently an Associate Professor at California State University, Long Beach, and working on incorporating stimulus-response compatibilities in 3-dimensional interfaces.

Congratulations to Dr. Vu on her award!

For some fun reading by Kim-Phuong Vu and Robert Proctor, see their review chapter on the state of our art:

Proctor, R. W., & Vu, K.-P. L. (2010). Cumulative knowledge and progress in human factors. Annual Review of Psychology (vol. 61). Palo Alto, CA: Annual Reviews.

The Human Factors of Weapons

James R. in California sends along a tragic story of police officer confusing his taser with his firearm.  The news story can be found here.  Here’s what James says:

An example taser

Here in CA there is a big to do over the shooting death of a young man (Oscar Grant) by a BART police officer Johannes Mehserle.  Apparently, Mr. Grant was being detained by Mr. Mehserle.

At some point Mr. Mehserle felt that Mr. Grant needed to be tasered (tased?). The police officer drew his weapon and fired, killing Mr. Grant. Mehserle had drawn his pistol instead of his TASER.

As you can see [ed: example taser on right] it is remarkably like a pistol in design and form.

The question now becomes “should non-lethal weapons look and act like lethal ones?