Use single-purpose device sessions for deep work

Block or exit everything except the one tool required for the current task during focused work periods.

Why it works

The mere presence of alternative apps — even closed — creates a low-level monitoring loop in working memory ("I could check…"), which reduces cognitive bandwidth available for the primary task. Full-screen single-application mode, combined with communication apps closed at the OS level, removes this competing attentional load. The computer becomes the task rather than a distraction device that also runs the task.

How to do it

1. Before a deep work session, close all browser tabs except the ones the task requires.
2. Quit (not just minimise) communication apps: email, Slack, messaging.
3. Use a full-screen mode on the working document or tool.
4. Set a timer (90 minutes is a natural ultradian rhythm boundary) and do not exit the mode until it ends.

Evidence

Cognitive load theory and attention residue research both support the value of reducing competing attentional demands during complex tasks. Studies on open-plan offices and multitasking show consistent costs to focus when alternatives are present. (observational)

Research on single-application focus specifically is sparse; extrapolated from multitasking-cost and attention residue literature.

Common mistake

Keeping a browser tab for "reference" during the session, which quickly becomes a check-email tab — the single-purpose rule must be literal to hold.