Unintended consequences of features: Lessons from an automobile

Posted by Christopher Hill on Feb 12, 2014 9:48:00 AM

Constraints can be beautiful

Several years ago (before I had worked with RSuite), I posted on my personal blog a couple of times on the merits of constraint in design http://blog.chiliarchy.com/search/label/constraint. At that time, I was dabbling in software design but had yet to be responsible for establishing and communicating constraints to the engineers building a software application.

The redesigned RSuite of today often challenged me and the engineering team to balance many competing opinions and interests. With an application offering the flexibility of RSuite, it is tempting to always do more.

Engineers tend to like building things. A good engineer's "can-do" attitude will favor developing enhancements. It's more fun to create new code. Going back through existing code to refactor, trim, or remove can sometimes feel like cleaning out the garage.

Customers often request more, seldom request less

Project managers, the tip of the spear when it comes to customer projects, are also often managing requests for features. Customers tell them they need a button, widget, dial or gadget and it seems simplest to just add it. Rarely does a request come in to remove anything.

Features have immediate and ongoing costs

It's obvious that a new feature costs something to build. Most people consider this when deciding whether or not a feature is worth adding. The more important factor is the long-term costs that aren't so easy to identify. A single button can have an exponential effect on the number of test cases and unintended interactions. Documentation and support have to be revised and maintained. More features often mean more visual elements for users to process when using the software. These penalties often seem relatively tiny when viewed in isolation.

An automotive example

I was on a work trip driving from Minneapolis to a city several hours away in a rental car. I rented a Ford Focus, a car I actually owned in 2000. It was a dark winter night in Minnesota, so I took time to check the lights, made sure I knew to to operate the various wiper modes, adjusted my mirrors, and familiarized myself with the climate controls and stereo.

Unexpected company

After 45 uneventful minutes on the road, I made a quick stop for food then headed back out on the dark two lane highway. Twenty minutes later a car overtook me from behind. Rather than pass, he tailgated for a few annoying miles. Suddenly a flood of police lights had me pull over to the side.

As the patrolmen cautiously approached I fumbled for the window controls.

The car "helps"

As I was trying to unroll the window, the Microsoft Sync voice came over the speakers asking how she could help. I didn't know what I had bumped that caused this but decided to first get the passenger window down. As it opened the patrolman asked for my license. As I retrieved my wallet the car's computer voice told the officer she didn't understand the command, could he try again? I began to try to explain when the car interrupted and began listing some examples of commands she could understand.

I fumbled around for an "off" switch. Suddenly the controls I thought I largely understood were becoming confusing. I turned off the key but she kept talking. I pushed several more buttons. I pulled the key out of the ignition. She kept talking. Then I remembered that the power to the accessories remained on until the driver opened the door. I gently pulled the door latch and she fell silent. The officer seemed mildly amused as he said, "Rental car?"

Good design or a trap?

Ford's engineers had done an excellent job adding lots of additional features to this car without making it seem unfamiliar.

A myriad of optional features were present, but not obtrusive. I had left the airport confident that I could competently operate the vehicle. Under stress, however, the inadvertent activation of voice control had suddenly made me realize the large number of controls I hadn't paid attention to. In my attempts to silence the computer I had tried pressing many of them. Would I regret some of those actions later?

Taillights-off mode

The patrolman informed me that I was driving with no taillights. I told him the headlights were working and that they must have burned out. He said that he had seen this a few months prior on a Ford pickup, and asked me to try all the positions for the light control. I turned the knob to several positions. "That's it. Remember that setting."

While he went back to his car with my license, I studied the symbols on the headlight control. What seemed so natural an hour ago now looked like symbols on an alien spacecraft. The patrolman returned with my license and wished me good night.

A dubious feature documented

I'm still not sure why the car could run with the headlights on and the taillights off. Later I consulted the owner's manual. To improve accuracy and save costs, automobile manuals are modular to accommodate re-use across models and provide for optional features. In the manual, there was what appeared to be a single page showing the use of the lights. No where was there any mention of the possibility of using headlights without taillights.

If you were reading the owner's manual cover-to-cover you'd find two more pages on the lights. When was the last time you've done that? At the end of the third page, below several optional features that were irrelevant and further encouragement to stop reading, was this warning.

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I had to read it a few times before realizing it applied to me. Although I still wasn't sure how this all played out. Even if we were to move the warning to a more prominent place at the beginning of the section and clarify its language, how many people have read the owner's manual before operating their car for the first time?

A lesson for IT projects

Whether designing a car, creating a piece of software or customizing an application for your organization, managing whether and how features are added is an important activity that is too often overlooked. It is easy to see how a feature might help when used as directed. The real challenge is in being able to see potential unintended consequences the feature may create.

Whether you are designing, modifying or selecting software, it is tempting to just list all the desired features and evaluate its presence or absence. Much harder is evaluating whether the features provided are provided in a usable way. Don't assume that more is always better. Sometimes a feature like "headlights on taillights off" can create problems for users.

If you find yourself having to place warnings or cautions in the documentation you should be reconsidering either the presence of or implementation of a feature.

Software often has an advantage over car design in that it is easier to add custom features to software. The CMS I work on, RSuite, makes it possible to implement features for a subset of users if needed. Sometimes customers complain that some feature isn't included.

Balancing features and design

RSuite has a flexible user interface that can accomodate a wide range of features. Menus can be rearranged and reorganized easily. This makes it not only easy to make product changes, but also can be used if a customer wishes to customize RSuite for addressing specific business requirements.

When developing the product we strive to balance the impact of additional features against the overall product usability. This often means looking for ways to clarify, simplify or modify other areas of the interface. It is also vital to test for unintended consequences that may inadertently create potential problems for users. 

Reflect on your design

A major goal as we work on our RSuite product is to find ways to design RSuite's interface to support the highly flexible architecture while discouraging practices that might create problems that are invisible or difficult to correct. This is a primary consideration whenever a user-facing modification is made to the interface. Even though objective perfection is not possible in any design, we strive to examine each implementation and look for potential refinements that could benefit the product as a whole.

We've made a number of refinements over the last several months from these activities, and have identified more substantial changes that will be rolled out in upcoming releases. Some of these will actually provide additional features to users while reducing complexity.

Potential signs of design problems

There are some areas that often indicate potential design problems. None of these are a smoking gun, but they are good starting points when reflecting on a design.

Does the feature rely on an "Are you sure?" confirmation before performing an action?

Do you find your support staff complaining that users don't read the manual? 

Are you putting cautions and warnings into your documentation?

Do you rely on users to report problems? Remember users often are unaware of problems they may have inadvertently caused - instead blaming the software.

Are there "irrational" complaints or support requests that cannot be reproduced? 

Are there support requests that have been marked "as designed"?

Have you looked at what aspects of product implementation require the most customization effort, documentation effort, or training effort?

More is not always better

Sometimes they are right and we add the feature. Other times the request is narrow, and adding the feature would probably result in more harm than good. It is easy to overlook this whether designing, modifying or evaluating software. Creating a long checklist of features is tempting. But make sure those features don't leave your users in the dark with their taillights off.

Topics: software design, documentation

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