What is the average time lost when interruptions break your train of thought?

Question

I'm looking for quantifiable results from studies; not best guesses please.

I quite frequently find that after an interruption I need to gather my thoughts and refocus on the task I was performing when I was interrupted. The time seems to vary depending on the complexity of the task and how long I've been interrupted for, and sometimes even how worthwhile I perceived the interruption to be.

For example, a pointless interruption costs me more in recovery time than a worthwhile interruption that I can mentally dismiss more easily. I'd very much like to know if there has been any research in this area and what the results show.

Answer 1

Such studies do exist, one of the more prominent probably being the ones conducted in Gonzalez, Mark 2004 and Mark, Gonzalez, Harris 2005. There's a good breakdown in a NY Times article dating Oct 2005.

Her summary was that on average, a task would be worked on for 11 minutes before an interruption would kick in. This interruption would lead to two different tasks being tracked in the aftermath, and about 25 minutes would pass before the original task was continued. Back at the original task, on average, 8 minutes would pass until back at the same level of focus as before, leaving only three minutes of focussed work until the next interruption. Mark differenciates if an interruption was related to the work it interrupted - if if was, it wouldn't count as interruption. What may seem surprising - her heroes interrupted themselves as much as they were interrupted by external sources. Guessing from your question, you'll probably like reading the papers and their findings yourself, and continuing your own research of related publications from there on.

Answer 2

This is explicitly not what you're looking for but just for others who may come across this question, I thought it would be valuable to point to Paul Graham's essay on this, where he suggests that the cost of interruptions is way more than anyone would reasonably think it could be: http://www.paulgraham.com/makersschedule.html

Answer 3

Also only of tangential interest, but I find that if I can train those around me to simply ask if they can interrupt, the time it takes for me to get back "in the flow" is much shorter.

I think it has something to do with being able to "wrap up" a thought or task. If someone says, "May I interrupt?" I can answer, "Just a minute," and get to a breaking point. But if they just start blurting out something, I have to stop, re-focus on what they're saying, evaluate if it's important or not, come back with a snappy rejoinder, etc.

Since I work at home, I have more control over this than most people. I've pretty much trained my spouse to behave this way, and I do the same with her, and I think we're more productive and more amicable then when we were constantly growling at each other for interrupting.