This barrier is even less of an imposition now that we have intra-office IM as the norm. If someone is in their office with the door closed, drop them an IM that they can read and act on when they&#x27;re finished with what they&#x27;re doing.<p>Maybe it matters less for non-programmers, but even a brief unexpected distraction can undo multiple minutes of mental effort for me. When I need to focus, the headphones go on, the door gets closed, and I intentionally erect barriers to interaction because it&#x27;s important that I not be distracted. That closed door is a feature, not a bug.