Imagine this. You’re forty minutes into a piece of work. The thinking is finally clicking, the sentences are starting to land in roughly the right order, and you can feel the shape of what you’re trying to say. Your laptop pings. A Slack message. You glance at it. It can wait. You turn back to the document. The cursor blinks at you. The sentence you were halfway through is gone, and so is the feeling that was about to put it on the page.
There is a name for what just happened to you. There is also a number to go with it.
What just happened is called attention residue
The term comes from Sophie Leroy, a professor at the UW Bothell School of Business. Leroy describes what it is in her own words: “as we switch between tasks (for example from a Task A to a Task B), part of our attention often stays with the prior task (Task A) instead of fully transferring to the next one (Task B). This is what I call Attention Residue, when part of our attention is focused on another task instead of being fully devoted to the current task that needs to be performed.”
The conditions under which it bites hardest, in her telling: “Attention residue easily occurs when we leave tasks unfinished, when we get interrupted, or when we anticipate that once we have a chance to get to the unfinished or pending work we will have to rush to get it done. Our brain finds it hard to let go of these tasks, and instead keeps them active in the back of our mind, even when are trying to focus on and perform other tasks.”
Her conclusion is the part worth pinning above a desk: “when you experience attention residue and keep thinking about Task A while working on Task B, it means you have fewer cognitive resources available to perform Task B. The impact? Your performance on Task B is likely to suffer, especially if Task B is cognitively demanding.”
And here’s roughly what it costs
For the cost, the most cited number comes from Gloria Mark, an associate professor at UC Irvine, who shadowed 36 knowledge workers for three days at the second-by-second level. In a 2006 Gallup interview she described what she found: that “most interrupted work was resumed on the same day” — 81.9 percent of it — and that “it was resumed, on average, in 23 minutes and 15 seconds.”
Twenty-three minutes and fifteen seconds. From the ping to the moment you actually return to the thing you were doing.
And Mark adds an important caveat. The return is not clean. In her words: “when you’re interrupted, you don’t immediately go back to the task you were doing before you were interrupted. There are about two intervening tasks before you go back to your original task, so it takes more effort to reorient back to the original task.” The Slack message doesn’t just steal twenty-three minutes. It also routes you through two other unrelated tasks before you arrive back at the sentence you’d been halfway through.
The day I realized I was doing this all day, every day
I came across the 23-minute number a few years ago while researching an unrelated post, and it landed badly. Not because the number itself shocked me. Because as soon as I read it I started counting backwards through my morning. A glance at email. A Slack reply. A two-minute look at something a friend had sent. Each one of those was perhaps a 23-minute crater I hadn’t noticed I was digging.
I had been treating my work hours as a single block. The research suggested I was actually getting maybe three or four real working stretches a day, and most of the rest was the slow climb back from the previous interruption.
I tried time blocking, more or less right away. The improvement was almost embarrassingly immediate. Within a week the work felt different in a way I would have struggled to describe before reading the research.
What I actually do to minimize it now
What follows is what has stuck. I am not a productivity expert and none of this is novel. It is the unglamorous version that has actually worked for me, and only because I started taking attention residue seriously as a real cost rather than a vague feeling.
I work in time blocks of 90 minutes to 2 hours. Inside a block I am doing one thing. The block has a clear start and a clear end, and within those boundaries I treat Slack and email and the news as off-limits. The point of the block is not to be heroic about focus. The point is to give the brain a window long enough to actually arrive at the work, do something, and finish a piece of it before the next switch.
I close every tab before I begin. Not just social media. Every tab. Open tabs are a low-grade form of switching cost; the eye finds them. A clean browser is part of the setup ritual, the same way wiping down a counter is part of cooking.
I do not have social media open while I work. Not minimized in a tab. Not on a second monitor. Not on my phone in front of me.
And when I am working in a café, which I do often, I use a hard physical break between blocks. When a block ends, I close the laptop, pack up, and walk to a different café. The walk is the transition. By the time I sit down somewhere else I have left the previous block where it was, and the new block can have all of me, not just whatever was left over after the residue had its share.
What is different now
None of these moves are dramatic on their own. They all attack the same thing: the slow leak of attention from one task to the next that the research describes. For me, they buy back most of the focused time I used to be losing without realizing it.
But here is the part I keep turning over. The fact that any of this works at all, that closing tabs and walking to a different café can meaningfully change the quality of a day’s thinking, says something uncomfortable about the conditions most of us are working under. The default environment is not neutral. It is engineered for the exact kind of switching that the research says quietly hollows out our capacity to think.
So the real question is not whether you can build a system to protect a few hours of attention. It is what it means that you have to. Most of a working life is now spent inside the twenty-three minutes between things, and almost nobody is counting them. I have started to. I am not sure I like what the count reveals.
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This article is for general information and reflection. It is not professional advice. For your specific situation, consult a qualified professional. Editorial policy →
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