Fragmented attention: what neuroscience actually says

There's a popular intuition that interruptions cost us time. What attention research has shown over the last twenty years is more uncomfortable: they cost far more than we think, and the cost persists after the interruption ends.

The key concept is called attention residue, described by Sophie Leroy in 2009. When we switch from task A to task B, part of our attention keeps processing task A for minutes. It doesn't end when we close the tab. And that residue degrades performance on B.