When people switch from one demanding task to another, their attention does not always move cleanly with them. A portion remains attached to the unfinished task, especially when there was no clear stopping point.
This lingering attention is sometimes called attention residue. It helps explain why a quick interruption can have an effect that lasts much longer than the interruption itself: the mind continues rehearsing what was left unresolved.
The problem is not simply that switching takes time. The new task receives only part of our cognitive capacity while another part keeps monitoring the previous one. Work can feel unusually difficult even when neither task is intrinsically complex.
One practical response is to leave a restart cue before switching. A short note describing the next concrete action gives the unfinished task a trusted place to wait and makes returning less costly.
A good focus system therefore protects transitions as carefully as it protects blocks of uninterrupted time. Closing a loop temporarily can matter almost as much as avoiding the interruption in the first place.