Attention Residue: Sophie Leroy’s 2009 Task-Switching Study
Attention residue is the focus loss Sophie Leroy documented in her 2009 task-switching study: switch early, and part of your attention stays behind.
Why it works
Sophie Leroy’s 2009 study — "Why is it so hard to do my work? The challenge of attention residue when switching between work tasks," published in Organizational Behavior and Human Decision Processes (109(2), 168–181) — demonstrated that when people switch tasks before reaching a natural stopping point, cognitive resources remain partially allocated to the unfinished task, reducing performance on the new task. Leroy named that leftover allocation "attention residue." The mechanism is that incomplete tasks stay active in working memory (Zeigarnik effect) until explicitly closed; her experiments found the residue was smaller when participants either finished the task or formed a concrete plan for finishing it. A structured task handoff creates that same closure, reducing the residue that would otherwise bleed into the next task.
How to do it
- When you must stop a task mid-stream, spend 2 minutes writing: what you just completed, the very next physical action, and any open questions.
- This "next-step note" allows the brain to release the task because it has a concrete re-entry point.
- Before starting the next task, read this note rather than picking up from a cold mental restart.
- Keep these notes in a dedicated "transition log" rather than embedded in the task itself.
Evidence
Sophie Leroy’s 2009 study directly demonstrated that switching to a new task before completing the prior one reduced performance on the new task, because cognitive resources remained allocated to the unfinished task — the effect she named attention residue. Participants who reached a stopping point, or who made a concrete plan for finishing, showed less residue than those who switched mid-task. (observational)
The attention residue research is observational and lab-based; the transition-note intervention is a practitioner application of the finding rather than a separately tested treatment.
Sources
Common mistake
Stopping mid-task with no documentation, relying on memory to restore context — which requires expensive reconstruction and increases the residue period before the next task can fully engage.
Practice this with IX Coach
More practices for Context Switching Cost: Why Task Switching Wrecks Focus
- Adopt a strict single-tasking protocol
Work on exactly one task until it reaches a natural stopping point before starting anything else.
- Triage interruptions before acting on them
When something interrupts you, categorize it as urgent-now or capture-for-later before deciding whether to switch.
- Minimize open tabs and windows during focus sessions
Close all browser tabs and applications not needed for the current task before starting deep work.
- Capture context before every forced switch
When a forced context switch is unavoidable, spend 60 seconds capturing exactly where you are before stepping away.
- Track your actual switch-cost pattern for one week
Measure how long it actually takes you to recover focus after a switch — the data is more persuasive than the concept.
Related concepts
- Deep Work, Made Practical
Focus blocks, attention residue, and the shutdown ritual — with the evidence
- Monotasking, Made Practical
The real cost of task-switching, and how to work one thing at a time
- Task Batching: Grouping Similar Work to Cut Switching Costs
Cut task-switching overhead by doing like work together — and why the sequencing matters