The November issue of pragpub has an interesting article on interruptions. The article is written by Brian Tarbox, who also mentions the article on his blog. I like the subtitle: ‘Simple Strategies for Avoiding Dumping Your Mental Stack’.

Brian talks about the effective cost of interrupting a ‘knowledge worker’, often with trivial questions or distractions. In the eyes of the interruptor, the interruption only costs the time the interrupted had to listen to the question and give an answer. However, depending on what the interrupted was doing at the time, getting fully immersed in their task again might take up to 15-20 minutes. Enough interruptions might even cause a knowledge worker to mentally call it a day.

According to this article interruptions can consume about 28% of a knowledge worker’s time, translating in a $588 billion loss for US companies each year.

interruptions can consume about 28% of a knowledge worker's time, translating in a $588 billion loss for US companies each year Click To Tweet

Looking for a new developer to join your team? Ever thought about optimizing your team’s environment and the way they work instead?

Making non knowledge workers aware

You can’t. Well, I haven’t succeeded yet. And believe me: I’ve tried. When you’ve got a simple way to really increase your productivity (‘give me 2 hours of uninterrupted time a day’) it wouldn’t be right not to tell your boss or team-leader about it.

The problem is: only productive knowledge workers seem to understand this. People who don’t fall into this category just seem to think you’re joking, being arrogant or anti-social when you tell them the interruptions can really have an impact on your productivity.

Also, knowledge workers often work in a very concentrated mental state which is described here as:

It is the same mindfulness as ecstatic lovemaking, the merging of two into a fluidly harmonious one. The hallmark of flow is a feeling of spontaneous joy, even rapture, while performing a task.

Yes, coding can be addictive and if you’re interrupting a programmer at the wrong moment, you’re effectively bringing down a junkie from his high in just a few seconds. This can result in seemingly arrogant, almost aggressive reactions.

How to make people aware of the production-cost they’re inflicting: I’ve been often pondering that question myself. The article suggests that solutions based on that question never seem to work. To be honest: I’ve never even been able to find a half decent solution for this question. People who are not in this situations just don’t understand the issue, no matter how you try to explain it.

Fun (?) thing I’ve noticed: Programmers or IT people in general who don’t get this are often the kind of people who just don’t get anything done.

Interrupt handling (interruption management?) IRL

Have non-urgent questions handled in a non-interruptive way

It helps a bit to educate people into using non-interruptive ways to ask questions: “duh, I have no idea, but I’m a bit busy here now could you put it in an email so I don’t forget?”. Eventually, a considerable amount of people will skip interrupting you and just send an email right away. Some stubborn-headed people however will continue to just interrupt you, saying “you’re 10 meters from my desk, why can’t we just talk?”.

Just remember to disable your email notifications, it can be hard to resist opening your email client when you know a new email just arrived.

Use Do Not Disturb signals

When working in a group of programmers, often the unofficial sign you can only be interrupted for something important is to put on headphones. And when the environment is quiet enough, often people aren’t even listening to music. Otherwise music can help to block the indirect distractions (someone else talking on the phone or tapping their feet). You might get a “they’re all just surfing and listening to music”-reaction from outsiders though.

Peopleware talks about a team where the no-interruption sign was placing a shawl on the desk. If I remember correctly, I am unable to locate my copy of this really excellent must-read book.
If you have all standardized on the same IM tool, maybe that tool has a ‘do not disturb’ setting. Also some phone-systems have a ‘DND’ (do not disturb) setting.


Brian offers a number of good suggestions, some obvious like: hide away somewhere they can’t find you. Not sure how long it’ll be till someone thinks you’re just taking a nap somewhere though. Also, this often isn’t possible or your boss might not understand this. And if you really get caught taking a nap, make sure to explain that your were powernapping.

Counter-act interruptions

Another suggestion he offers is when you’re being interrupted to just hold up your hand, blocking the interruption, and at least giving you time to finish your sentence or your block/line of code. The last suggestion works more as a way to make it obvious to the interruptor that they really are interrupting your work and to offload some of the cost on the interruptor. In practice, this can also helps you cool down a bit so you don’t start saying nasty things to the interruptor.

Unfortunately I’ve sometimes been confronted with people who just ignore this signal and keep talking, as if they’re sure that whatever they’ve got to say is really worth listening to and without a doubt more important than anything you might be doing.
This behaviour usually leaves me speechless (not good when someone just asked a question). I’ve noticed that these people are usually also the first to complain when being interrupted themselves. They’re generally not very liked as colleagues, so try not to imitate their behaviour.

TDD as a way to minimize recovery time

I don’t like Test Driven Development. Mainly for only one reason: It interrupts flow. At least, that’s what it does for me, but maybe I’m just not grown used to TDD yet.

BUT a positive effect TDD has on me when I have to work in an interruptive environment and can’t really get into the ‘flow’ (also supposedly called ‘the zone’ by software developers, although I’ve never heard it 1st hand), TDD helps me to concentrate on the tasks at hand and helps me to get back at work after an interruption. I feel when using TDD, I can get by without the need for being totally ‘in’ the project and I can be reasonably productive without obtaining ‘flow’.

Do you have a suggestion on how to make people aware of the concept of ‘flow’ and the cost of interruptions? (without looking like an arrogant ass or a weirdo)