Deep Work — the multitasking myth and the cost of interruption

My most ingrained open-space habit was: “I'll answer on Slack, then back to the code.” A year in, I noticed those “then back” moments piled up to dozens a day, and the code was not happening. I checked what the research says. The answer was sharper than I expected: it is not just lost minutes, it is a durable drop in the ability to focus.

Heavy multitaskers do worse, not better

Ophir, Nass and Wagner (2009, PNAS) split Stanford students into “heavy media multitaskers” (HMM) and “light media multitaskers” (LMM) based on how many parallel media streams they reported (Spotify + Slack + two monitors, etc.). Then everyone took standard attention and working memory tests.

Results were the opposite of the authors' intuition: HMMs did worse at filtering distractors, worse at working memory, worse even at task switching itself — the very thing they should have been trained for. Hypothesis: the habit of consuming many streams in parallel trains attention to react to everything, at the cost of the ability to ignore the irrelevant.

The cost of an interruption: 23 minutes

Mark, Gudith and Klocke (2008, CHI) observed office workers with audio recorders and field notes. The average gap between interruptions was 3 minutes 5 seconds. Average time to return to full concentration on the original task: 23 minutes 15 seconds.

Simple arithmetic: 5 unplanned interruptions in a morning add up to ~115 minutes of recovery — almost two hours where you are technically working and practically just returning. Mark in later work (2014) also showed that more interrupted workers reported higher stress and a stronger sense of time pressure, independent of objective workload.

A second important finding: about half of interruptions come from the worker themselves. You cannot blame everything on Slack and colleagues.

Mind wandering costs happiness

Killingsworth and Gilbert (2010, Science) did something that today would be hard: they built an iPhone app that randomly pinged 2250 participants asking: what are you doing? are your thoughts on what you are doing? how do you feel?

Result: people's minds wandered on average 47% of the time. Crucially — mind wandering strongly predicted lower mood, even when the wandering content was pleasant. Time-lag analysis suggested wandering caused the mood drop, not the other way around.

The implication for deep work is double: focused work is not only more effective, but also more pleasant while it happens. The subjective “I'm bored” usually shows up in the first minutes of resistance — push through and you enter what Csikszentmihalyi (1990) called flow.

Newport — read with distance

Cal Newport (2016, Deep Work) packaged these threads into a popular book. His main claim — that the capacity for deep work will become rarer and therefore more valuable — is reasonable, but the book occasionally drifts into self-help rhythm and deserves a sceptical read. Concretely: Newport does not cite a study that shows his “4 rules” work in a controlled experiment.

What is solid in Newport, and backed by Mark, Killingsworth and Ericsson (1993, deliberate practice), are two principles: (1) real learning and creative work require uninterrupted blocks of at least 60–90 minutes; (2) the capacity for such blocks is itself a skill you train — or dismantle by constant multitasking.

What to do

• Schedule one 90-minute block per day with notifications off. Just one, but immovable.
• Do not open the browser or Slack as the first thing. The first hour = your work, not other people's priorities.
• Measure interruptions for a week (tally on paper). Half will be yours — start there.
• Phone out of arm's reach, not on the desk. Ward et al. (2017): mere presence of a smartphone lowers working-memory scores, even when silenced.
• Treat the boredom of the first 10 minutes as part of the protocol, not a signal to check email.

Sources

1. Ophir, E., Nass, C., & Wagner, A. D. (2009). Cognitive control in media multitaskers. PNAS, 106(37), 15583–15587. doi.org/10.1073/pnas.0903620106
2. Mark, G., Gudith, D., & Klocke, U. (2008). The cost of interrupted work: More speed and stress. CHI 2008 Proceedings. doi.org/10.1145/1357054.1357072
3. Mark, G., Iqbal, S. T., Czerwinski, M., & Johns, P. (2014). Bored Mondays and focused afternoons: The rhythm of attention and online activity in the workplace. CHI 2014.
4. Killingsworth, M. A., & Gilbert, D. T. (2010). A wandering mind is an unhappy mind. Science, 330(6006), 932. doi.org/10.1126/science.1192439
5. Csikszentmihalyi, M. (1990). Flow: The Psychology of Optimal Experience. Harper & Row.
6. Ericsson, K. A., Krampe, R. T., & Tesch-Römer, C. (1993). The role of deliberate practice in the acquisition of expert performance. Psychological Review, 100(3), 363–406.
7. Newport, C. (2016). Deep Work: Rules for Focused Success in a Distracted World. Grand Central Publishing.
8. Ward, A. F., Duke, K., Gneezy, A., & Bos, M. W. (2017). Brain drain: The mere presence of one's own smartphone reduces available cognitive capacity. Journal of the Association for Consumer Research, 2(2), 140–154.