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AskTog, June, 2003

Multiple Mistakes Drown Interface

   A single major error can damage an interface. Make two of them and you're in real trouble. Make it three or four and you're doomed.

The following delightful letter illustrates the dangers of compound error all too well.

Letter from Joe Moran

I’m a member of the Building and Grounds committee at our Quaker meeting house. This month, when the group got together to check out problems around the building, someone had posted a hand-written sign on our new ultra-quiet dishwasher: “Do not operate the dishwasher unless John or Bettie is here to help!”

Now, we had heard that people were having trouble with the dishwasher, but it’s one of those new jobs that doesn’t have any dials or switches on the front, just a touch panel and lots of little green LEDs. We figured it would just take people a little while to get used to it.

Anyway, one of the older women in the Meeting decided the dishwasher wasn’t working properly and called the manufacturer. The manufacturer dispatched a service rep. The service rep came out, looked over the dishwasher and declared that everything was in perfect working order. He showed the woman how to operate the dishwasher and charged us $40 for “consumer education.”

I looked at the dishwasher. It seems simple enough. There’s a row of buttons that lets you choose the kind of cycle you want to run: normal, pots, china, etc. In all, I’d say there are about eight different selections. There’s a start button. Inside, there’s the standard detergent cup. You load the detergent cup, close it. Shut the door, choose your cycle, and push the start button. The dishwasher washes.

They told me about a special feature the dishwasher has that I think is nice: reset. If you get the thing started but then decide you chose the wrong setting, or if you just want to shut the thing down, you hit reset. The dishwasher interrupts its current cycle, dumps the water, and returns to ready state.

One of the other members of the Building and Grounds group told me that she’d heard from someone else who had investigated the problem they were having that “if you hit the Start button twice in a row, it locks the dishwasher into a reset cycle for an hour.”

This sounded unlikely to me, so I took another look.

There’s not a Start button and a Reset button. There’s just one button: Start/Reset.

People have been loading the dishwasher, choosing the cycle, then hitting start. This is an ultra-quiet model. They hear nothing. They think they’ve failed to hit the Start button squarely and hit it again. But they’re not hitting the Start button at that point, they’re hitting the Reset button.

The dishwasher then takes (not an hour) but a couple of minutes to go through the reset process, drain the water, and prepare for new instructions.

Meanwhile, the user sees nothing happening. They hit the Start button again, but the dishwasher is still resetting. At this point, the dishwasher is already two punches of the Start/Reset button behind the user and not responding. So the user hits the Start button several more times.

It turns out that three consecutive punches pops open the detergent cup and dumps the soap--probably a diagnostic trick for the repair peopple--so more likely than not, the user punches the Start/Reset button enough times to dump the detergent AND drain the water. Now she’s just flushed her soap as well as getting totally pissed off.

There are two very small LEDs on the opposite side of the touch panel that indicate “Sensing” and “Washing.” If the user notices these (or listens very carefully) she’ll notice that the first punch of the button did the trick and the machine has started. Otherwise, there’s nothing to indicate that the machine starts operating when the user hits the Start button.

OK, so every company makes a bad design once in a while. But this dishwasher is a GE, the same people who engineer components for our nation’s nuclear arsenal. Should we be concerned?

Joe Moran, Denver, CO

Tog Replies You folks must have the same model as the nice people at the church in Lake Woebegone. In their case, all the ladies who had held court in the kitchen for so many years suddenly went into retirement after the arrival of the new, easy-to-use dishwasher.

The GE dishwasher suffers from two separate and distinct design defects, either one of which would have made its use difficult. Combined, they are a recipe for disaster.

Mistake 1: Simple visual appearance doesn't = simple interface

Not only does a simple visual appearance not automatically result in a simple interface, it usually results in the opposite, unless the task domain is equally simple--and foolproof.

Often, the only thing a simple visual interface indicates is reduced manufacturing costs, as hardware is pulled out by the roots, with software left to clean up the mess.

That is certainly the case with the horrible clocks we've been saddled with in this digital age that only allow you to set the time in a single direction.

Couple such cost cutting with inferior software design and you end up with a frustrated consumer. Can no clock chip designer figure out that no one needs to get up at exactly 6:03? If they just allowed the alarm sequence to go forward in five minute increments, instead of one minute increments, they would improve our lives immeasurably.

Then there are the designers who really like a good challenge, like the challenged folks at BMW who have managed to reduce all the clutter of controls in the high-end BMW 7 Series to such an extent that the dozens of dials and controls that used to populate the center console have been replaced by a single knob, the iDrive (googleSearch) with claimed access to 700 different functions. The boys at PistonHeads said it best:

[Any] device that requires you to take one hand off the wheel while distracting you from the road ahead is positively Darwinian. BMW's...iDrive is in a different league: challenging you to check your tyre pressure in the middle of a skid.

The trouble is, no one but the designers can use it. The dealers actually offer one and two day courses in how to, for example, adjust the air conditioning. Somehow BMW didn't think this would be a problem. Quite the contrary: They continue to crow about how "intuitive" it is. For shame!

The Beemer looked really cool at the auto shows, and equally slick on the showroom floor, yet another demo that looked so cool it shipped.

People think that a GUI interface is simple, on account of all you have is a mouse and a screen, but look at the informational complexity of that screen. Users deal with far more variables than was ever imagined in the days of MS-DOS. It is that messy complexity that gives them the power to perform tasks unthinkable in the days of MS-DOS.

The complexity of other people's screens, particularly that of new users, who leave everything open everywhere, often leads observers to conclude that something must be done to take control of their screens and clean them up, by putting everything away neatly. No! Many people work well in clutter. They know where everything is, and just how to get to it quickly, without having to remember where they left it.

Mistake 2: Subtlety is not a virtue

Pilot lights gleaming at aesthetically pleasing locations, rather than at the focus of the user's attention, are useless, as in the case of the dishwasher. If you save even more money, resulting in ambiguous meanings, they can even be dangerous.

Consider the case of the budding terrorist a few years ago who failed to notice the subtlety of the pilot light which was not lit up to indicate that the time was set 12 hours off.

The terrorist thought he had set the clock to, for example, 8 PM, the current time, and the alarm for 11 AM, when he would have safely (?) delivered the bomb.

Unfortunately for him, he had set the both the clock and the alarm to PM. The bomb blew him up in his sleep shortly thereafter. (How the crime boys reconstructed that one, I'll never know.)

You know the alarm clocks I mean, of course. Their builders save money by not having both an AM and a PM LED. The LED is off for AM, on for PM. Pretty subtle, subtle enough to kill.

Mistake 3: Hidden shortcuts aren't It actually is possible to shield users from diagnostic procedures, by having them press a number of isolated keys or hidden buttons within a keypad simultaneously, for example. In the case of the dishwasher, having the On button dump the soap dish is just clearly a bad idea.

Microsoft is notorious for adding "shortcut" keys to everything. I'm forever getting weird results in Microsoft Word when my fingers accidentally press down on what I don't know as I type and having some strange window fly open.

On the Mac, I've grown use to the Mac help system ponderously spinning itself up from deep, deep sleep at random intervals, obviously in response to some slip of the keyboard or mouse on my part.

Apple, at least up through System 9, has done a nice job with "power user" features, which are often attached to the Option key. Press that key while opening menus, selecting buttons, etc., and interesting things might happen. Leave it alone, and things will go on in their normal course.

(I just discovered one such Mac feature today, after 20 years of using the machine: Option click on a title bar and, instead of just "rolling up" the current window, it will "roll up" all the windows in the application.)

Apple has failed, unlike Microsoft, to "booby trap" every single possible key on the keyboard, making for a less jarring experience.

If you want to add power-user features--and you do--either test them to make sure they will not hamper the majority of your users, or ship them turned off, with, preferably, a single that will enable them all at once.

Which brings me to the coup de grace that GE gave themselves, ensuring their products ultimate failure in Denver, as well as Lake Woebegone.

Mistake 4: Failure to test under "real world" conditions

Private vs. Public

What works in a home, where users have the manual and sometimes take the time to read it, won't necessarily work in public settings.

Unless you are testing under a variety of conditions, your product will fail under a variety of conditions.

We have a dishwasher with subtle controls, not unlike the GE's. We've learned to use it. We have no problems now, although we certainly did when we were learning.

The problem with such an appliance in the public setting is that you have a constant flow of new people, all needing to learn how to use it. That's why commercial laundry machines continue to use easy-to-understand, easy-to-operate mechanical controls.

Quiet vs. Noisy

What works in a quiet lab doesn't necessarily work in a noisy--or even normal--environment.

I learned the GE lesson back in the '70s, when my partner, David Eisenberg and I were working on a tutorial to be packed with every Apple II. We tested it thoroughly in the lab, ensuring that it would work with new users who had never even touched a computer before. Then we took it to a computer show.

The screen would periodically lock up, as the computer fetched new information off the floppy disk. Always before, the sound of the head scrubbing the disk alerted people to the fact that the system was busy processing their command. Suddenly, even those noisy early drives were drowned out by the cacophonous crowd around them. It appeared the system had crashed.

We returned to Apple and put in visual delay indicators "Fetching information from the disk"), and the problem was solved.

There's nothing inherently complex or confusing about electronic controls. It's just that they are, almost universally, poorly implemented. Someday, someone will stop using them as an excuse for pulling out parts, and they will instantly become easier to use than their mechanical counterparts.

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