What are Levels of Interruption, and why do they matter?

I admit it… I have attention deficit disorder. I easily get distracted. Unfortunately, data shows that most of us do too.

Whether it’s viewing a web site or trying to use an ATM machine, users can quickly get thrown off their original task. If we don’t consider interruptions carefully in the design of our products and services, customers will at best be slowed down by distractions and at worst will abandon our products entirely. Here’s how you can fix the interruptions that matter the most.

In a groundbreaking study of response time on computer terminals in 1979, Walter Doherty of IBM’s Watson Research Center noticed that "...each second of system response degradation leads to a similar degradation added to the user's time for the following [command]. This phenomenon seems to be related to an individual's attention span. The traditional model of a person thinking after each system response appears to be inaccurate. Instead, people seem to have a sequence of actions in mind, contained in a short-term mental memory buffer. Increases in system response time seem to disrupt the thought processes, and this may result in having to rethink the sequence of actions to be continued."

Anything that delays a user in getting a task accomplished can affect more than just their time to complete the task, because users are … well, human … and the mind can easily wander.

Whether you are designing a telephone menu, a web site, an automobile, or a blender, paying attention to reducing delays is critical. But which ones do you focus on?

I was part of a team that worked on reducing delays in unpacking and installing one company’s products. We made great strides in simplifying the installation instructions, reducing the amount of packaging, and minimizing the tools needed for the job. We thrilled customers with our easy installation, but the product was still only a marginal success. Why? We missed fixing some fundamental operation interruptions that users deal with day in and day out. The team should have spent our time here first.



I call this concept “levels of interruption.” Users may only open the package and install your product once, they might read the manual five or six times, they might use a primary function every day, and they might watch the display screen every second. Which area should you focus on first? The last one, of course. This is where your users will spend the most time and it is also where they will be interrupted by the same issues over and over again. Once you are certain that the most frequent level of interruptions are reduced, go to the next higher level and do it again until you are certain that level delights your user. Ideally, you’ll go through them all. But the reality is that at some point you have to make a business decision that a product or service is good enough. Just focus on the most critical ones first.

By paying attention to these levels of interruption, you can greatly increase the usability of your product. And your customers will thank you with repeat business and recommendations.

I have an Audi. It’s a nice car. But it does one thing that irritates me. Every morning when I get in the car and turn on the radio, the volume is lower than where I left it the day before. Each day, I have to turn up the volume to the place I like it. And each day I say to myself, “I wish they would fix that.” And yet, an Audi representative has never knocked on my door and said, “Mr. Hildebrandt? We’re here to fix your radio.” Instead, my radio will be that way until the junk man hauls away the car, and every morning I will continue think the same thought.

It’s important to consider that a simple decision by an engineer that seemed logical at the time will be something your customers may have to live with every day for literally decades. That’s why you need to put your products in front of real customers and find these little irritations before they get sold to your customers. Get rid of the interruptions people run across every day or every minute, and you will have delighted customers for life. I guarantee it.

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