The cost of context switching

The Idea

Sophie Leroy, a researcher at the University of Minnesota, coined the term attention residue to describe what happens after a task switch. When you move from task A to task B, part of your cognitive attention doesn’t move with you — it lingers on A, still processing, still holding open loops. You’re not multitasking. You’re running task B with a compromised instrument.

The damage is layered. The first layer is speed: work takes longer because your mind is split. The second layer is quality: the decisions you make on task B are made with less capacity than you think you have. The third layer — the most insidious — is that you often can’t feel it. Partial attention feels like attention. Divided focus feels like focus. The degradation is invisible until you see the output.

This is why a single hour of uninterrupted work often produces more than three “busy” hours of switching. It is not that the uninterrupted hour contains more minutes. It is that it contains more of you.

One Question

Where in your day are you switching between tasks and calling the result focus?

Today’s Action

Pick one task you’ve been doing in fragments. Block 45 minutes for it — nothing else open, phone away. Do only that task.

When you finish, note how much ground you covered compared to a typical interrupted session. That difference is the real cost of context switching, made visible.

Go Deeper

Attention residue doesn’t only live between tasks — it accumulates across a day. A morning of constant switching leaves an afternoon that’s already compromised before the afternoon’s first distraction arrives.

Sources

• Sophie Leroy — Attention Residue Research