Why Attention Residue Lingers at Work
Attention residue is usually described as the cost of switching. The studies behind it tie the cost to unfinished work and to expecting to return, and one of them tests a short plan that reduces it.
Answer to the question
Why does switching tasks leave part of your mind behind?
Because the earlier task can stay active when it is unfinished. In Sophie Leroy's 2009 experiments, difficulty disengaging from an unfinished task hurt performance on the next one, and merely finishing the first task did not remove the effect. Finishing under time pressure did, which she explains as cognitive closure: a task that feels done lets attention move.
Key takeaways
- Sophie Leroy's 2009 experiments measured attention residue as fast recognition of words from an earlier word task. Merely finishing that task did not remove it, and finishing under time pressure did.
- Leroy and Theresa Glomb found in four studies in 2018 that expecting to resume an interrupted task under time pressure produced attention residue, and that a brief ready-to-resume plan reduced it without harming performance on the new task.
- Masicampo and Baumeister's 2011 paper found that plan making can eliminate the cognitive effects of unfulfilled goals, a related result with a different design.
- Cal Newport's Deep Work cites Leroy correctly at pages 41 to 43 and uses her finding to support an equation she did not test.
Sophie Leroy measured attention residue by how quickly people recognised words that belonged to a task they had already left. A fast response meant the old task was still active. What the experiments found is narrower than the line now repeated in books on focus: attention stayed with work left unfinished, expecting to return to it under pressure keeps it there, and a short plan made on the way out appears to loosen the hold.
Unfinished work keeps its hold on attention
Leroy's paper in Organizational Behavior and Human Decision Processes reports two experiments. Each began with a word task, followed by a lexical decision task in which participants judged whether strings of letters were real words, followed by a task appraising CVs. Some of the real words in the lexical task came from the first word task.
The first task was either one that could be completed or one that could not, and half the participants worked under time pressure. The abstract reports that difficulty disengaging from an unfinished task hurts performance on the next one. Merely finishing the first task did not remove the effect. People who finished it under time pressure showed fewer signs that their attention was still stuck on it, and in the second experiment they did better on the CV task than people who finished without time pressure or did not finish. Leroy's explanation is closure. Finishing fast gave participants the most confidence that the first task was done, and a task that feels done lets attention move.
The 2009 experiments used undergraduates, 84 and 78 of them according to the British Psychological Society's Research Digest, a secondary report. The full text sits behind a paywall, so those figures are as the digest gave them. What the experiments measure is word recognition in a laboratory. They do not measure how a working day goes, and attention residue should be read as a measured tendency, not as a count of lost minutes.
A plan can close the loop on an open goal
Masicampo and Baumeister published a different kind of study in 2011. Their subject was unfulfilled goals rather than interrupted tasks, and their title states the result: plan making can eliminate the cognitive effects of unfulfilled goals. In their experiments a specific plan for the unfinished goal removed the intrusive thoughts it otherwise produced.
The result belongs to an older line of work. The Zeigarnik effect, from a 1927 study, holds that interrupted tasks are better remembered than finished ones, and it is often invoked to explain why unfinished work nags. A 2025 meta-analysis of 38 publications found no memory advantage for interrupted tasks, and found that people went back to an interrupted task about two times in three. The piece on The Zeigarnik Effect at the Credits sets that out. The finding matters here because Leroy's measure was never recall. It was how quickly related words were recognised, which makes attention residue a claim about attention, and the memory literature leaves it untouched.
Leroy's later studies, and what they found
Leroy extended the work herself. A 2016 paper, three studies, combined attention residue with regulatory focus theory and found that the framing of the interrupted task and the framing of the interrupting task interact to affect how well people switch. Its abstract does not report the direction or size of the framing effects, so nothing more is claimed here.
The 2018 paper with Theresa Glomb, four studies, changed the question. When people expected to resume an interrupted task under time pressure, they found it harder to give attention to the task that had interrupted them, which produced attention residue and weaker performance on it. A ready-to-resume plan, a brief reflection on and plan for the return to the interrupted task, reduced the residue, and performance on the interrupting task did not suffer.
A university news report on the work describes the plan as a minute spent noting your place in the project and your planned next step, and quotes Leroy as saying it "allows the temporary, cognitive closure that makes the attention switch possible." Time pressure helped in 2009, when it came while finishing, and hurt in 2018, when it was expected on return.
| Study | What changed | What it reported |
|---|---|---|
| Leroy, 2009, two experiments | First task completable or not, with or without time pressure | Difficulty disengaging from unfinished work hurt later performance. Finishing alone did not release attention, and finishing under time pressure did |
| Masicampo and Baumeister, 2011 | A specific plan for an unfulfilled goal | The plan eliminated the cognitive effects of the unfulfilled goal, in the paper's title |
| Leroy with a co-author, 2016, three studies | Framing of the interrupted and interrupting tasks | The framings interact to affect switching, with no direction reported in the abstract |
| Leroy and Glomb, 2018, four studies | Expected time pressure on return, and a ready-to-resume plan | Expecting to return under pressure produced residue and weaker performance, and the plan reduced residue without harming the new task |
Three of the four rows above carry Leroy's name. The evidence is consistent and well designed, and mostly one research programme: a fresh search for this piece turned up no independent replication and no large multi-laboratory test. Nobody should promise a particular gain from the plan in a real office.
Where Deep Work borrows the finding
Cal Newport's Deep Work, also from 2016, handles the citation properly. On pages 41 to 43 it names Leroy, names the paper and explains the lexical decision method in a footnote. Newport then sets the finding under his own equation, High-Quality Work Produced equals Time Spent multiplied by Intensity of Focus, which appears on page 40, as the mechanism for why intensity matters.
The equation has no units and nothing has been measured with it. It states a trade-off in the typography of arithmetic. Leroy's participants did word tasks in a laboratory, and her paper does not test how much a person produces at work, and the finding supports the idea that divided attention costs something and does not license the formula. Newport also wrote before the 2018 plan study, which is why Deep Work offers no ready-to-resume note.
Other work shows how the cost of interruption can appear. Gloria Mark and colleagues reported in a 2008 experiment that interrupted work was often completed faster, at the price of more stress, frustration, workload and time pressure. Attention residue may therefore show up as strain before it shows up as slowness. That reading is an inference, because Mark's study was not designed to measure attention residue. A 2005 field study by the same group found that roughly half of workers' interruptions came from inside, a point taken up in Self-Interruption Is Half the Story.
Before leaving a task, write down where you stopped and what comes next. Showing work in progress to other people has costs of its own, set out in Never Show a Fool Your Work Until It Is Complete. The mind seems to let go of a task that feels closed, so a note of where you stopped and what comes next is a cheap test, made in a minute before you switch, of whether anything about the task still feels open, and it asks for nothing more than that.
Common questions
Why does switching tasks leave part of your mind behind?
Because the earlier task can stay active when it is unfinished. In Leroy's 2009 experiments, difficulty disengaging from an unfinished task hurt performance on the next one, and merely finishing the first task did not remove the effect. Finishing under time pressure did. Her explanation is cognitive closure: a task that feels done lets attention move.
Is attention residue the same as the Zeigarnik effect?
No. The Zeigarnik effect is a claim about memory for interrupted tasks, and a 2025 meta-analysis of 38 publications found no memory advantage for them. Attention residue is a claim about attention, measured in the speed of recognising words from the earlier task. Both concern unfinished work, and they use different measures.
Does a note about where you stopped reduce attention residue?
Leroy and Glomb found in four studies in 2018 that a brief ready-to-resume plan reduced attention residue without harming performance on the new task. Masicampo and Baumeister found in 2011 that planning removed the effects of unfulfilled goals. Neither measures the size of the benefit in everyday office work.
How long does attention residue last?
Nothing we read gives a duration. The 2009 study measures recognition speed in a laboratory, not minutes, so a minute figure quoted without a paper deserves caution.
Sources
Leroy, S. (2009). 'Why is it so hard to do my work? The challenge of attention residue when switching between work tasks.' Organizational Behavior and Human Decision Processes, 109(2), 168-181. doi:10.1016/j.obhdp.2009.04.002.
Leroy, S., & Schmidt, A. M. (2016). 'The effect of regulatory focus on attention residue and performance during interruptions.' Organizational Behavior and Human Decision Processes, 137, 218-235. doi:10.1016/j.obhdp.2016.07.006.
Leroy, S., & Glomb, T. M. (2018). 'Tasks Interrupted: How Anticipating Time Pressure on Resumption of an Interrupted Task Causes Attention Residue and Low Performance on Interrupting Tasks and How a Ready-to-Resume Plan Mitigates the Effects.' Organization Science, 29(3), 380-397. doi:10.1287/orsc.2017.1184.
Masicampo, E. J., & Baumeister, R. F. (2011). 'Consider it done! Plan making can eliminate the cognitive effects of unfulfilled goals.' Journal of Personality and Social Psychology, 101(4), 667-683. doi:10.1037/a0024192.
Ghibellini, R., & Meier, B. (2025). 'Interruption, recall and resumption: a meta-analysis of the Zeigarnik and Ovsiankina effects.' Humanities and Social Sciences Communications, 12, article 962. doi:10.1057/s41599-025-05000-w.
Zeigarnik, B. (1927). 'Das Behalten erledigter und unerledigter Handlungen.' Psychologische Forschung, 9, 1-85. doi:10.1007/BF02409755.
Mark, G., Gudith, D., & Klocke, U. (2008). 'The cost of interrupted work: more speed and stress.' Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '08), 107-110. doi:10.1145/1357054.1357072.
Mark, G., González, V. M., & Harris, J. (2005). 'No task left behind? Examining the nature of fragmented work.' Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '05), 321-330. doi:10.1145/1054972.1055017.
Newport, C. (2016). Deep Work: Rules for Focused Success in a Distracted World. New York: Grand Central Publishing. Chapter One, pages 40 to 43 and the footnote on page 42.
British Psychological Society Research Digest (2009, 29 July). 'The surprising benefits of time pressure at work.' Secondary report of Leroy (2009), the source of the sample sizes and the experimental design as described here.
University of Washington Bothell (2019, 12 February). 'Fresh insights into workplace interruptions.' https://www.uwb.edu/news/2019/02/12/task-interrupted Source of the description of the ready-to-resume plan and the quoted sentence.