“The Cost of Interruptions” by Eric Wilson

Fun Fact: According to recent studies, interrupting your work to check your email can waste as much as 16 minutes.

On many occasions I have found myself having to explain to those outside of the software engineering world why unplanned interruptions are so, well, disruptive. I have tried to describe the mode of being in the zone, so completely deep in the understanding and comprehension of a task that a phone call, a question or just the need to say ‘hello’ to an engineer in the zone is like pulling out the wrong block during an intense game of Jenga – everything falls down.

To be crystal clear – it is an extremely fragile period of enlightenment.

Much to my delight, Chris Parnin (@chrisparnin) over at ninlabs research did a nice writeup of the effects of interruptions on productivity and focus – accompanied with the requisite scientific rigor. From his post: Based on a analysis of 10,000 programming sessions recorded from 86 programmers using Eclipse and Visual Studio and a survey of 414 programmers (Parnin:10), we found:

  • A programmer takes between 10-15 minutes to start editing code after resuming work from an interruption.
  • When interrupted during an edit of a method, only 10% of times did a programmer resume work in less than a minute.
  • A programmer is likely to get just one uninterrupted 2-hour session in a day.

Brutal. When is the worst time to interrupt an engineer? Research shows that the worst time to interrupt anyone is when they have the highest memory load. Using neural correlates for memory load, such as pupillometry, studies have shown that interruptions during peak loads cause the biggest disruption

I call it ‘being in the zone’ – Chris calls it ‘highest memory load’.

This real cost in lost productivity is a notion I’ve been describing for so many years. I’m glad that it has somewhat been quantified.

Fascinating stuff and a great read. I highly recommend it to those who find engineers to be the grumpy sort. It may just change your opinion.

Eric Wilson,
VP/Head of Product and Technology @ ScoreBig

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