RDEL #75: How do interruptions impact different software engineering activities?

Interruptions have a measurable impact on software engineers, but not all interruptions are equal. The research shows that the authority and urgency of an interruption amplify its disruptive effect, and that in-person interruptions, while physiologically less stressful, are perceived as far more annoying than on-screen alerts.

Duke and Vanderbilt researchers ran a study with twenty engineers performing three core tasks-code writing, code comprehension, and code review-while being hit with six types of interruptions, both in-person and on-screen. Participants wore wristbands that captured heart-rate variability and also reported their stress levels after each interruption.

Key findings include: urgent or high-dominance interruptions slow progress the most; in-person interruptions extend code-review time but actually lower physiological stress; simpler comprehension tasks suffer more from interruptions than complex ones; code-writing interruptions generate the highest stress scores; and perception data often diverges from physiological measures, with engineers feeling more stressed by in-person interruptions even though their bodies show less stress.

Leaders should treat perception as the leading indicator because it drives behavior. Measure interruption impact with surveys and telemetry, establish a baseline, and iterate quarterly. Reduce high-dominance interruptions by limiting urgent requests from senior staff during deep-focus windows, and protect code-writing time with calendar "Do Not Disturb" blocks and cultural norms that respect those periods.

Understanding these nuances lets engineering managers cut unnecessary noise, improve team performance, and protect morale, especially in remote settings where digital notifications multiply. By aligning policies with how engineers actually experience interruptions, you create a calmer, more productive environment.