The Cost of Interrupted Work: More Speed and Stress
https://ics.uci.edu/~gmark/chi08-mark.pdf
Method
"A 3x2 factorial experimental design was used. The within-subject factor was interruption context with three levels: no interruption (B, baseline), same-context interruption (S), and different-context interruption (D). The order of interruption context was fully counter-balanced."
Population
"Forty-eight subjects participated. 81% of subjects were German university students with a mean age of 26"
What it does not show
A lab study of clerical email work by university students over one short session, not programming or debugging, and not professional engineers. Measures no cumulative or chronic effect. “No difference in quality” was assessed on email length and politeness proxies, so it cannot be read as evidence that interruptions do not affect software defect rates.
Gloria Mark, Daniela Gudith, Ulrich Klocke
“people completed interrupted tasks in less time with no difference in quality” — subjects compensated by working faster — but stress and frustration were significantly higher in both interruption conditions than baseline. The cost of interruption showed up in the human, not in the output.
Tier I: A true controlled lab experiment: within-subjects, fully counterbalanced 3x2 factorial design including a no-interruption baseline compared against two interruption conditions.