eleven minutes and four seconds
Psychology measured the switch. HCI named the unit. Sociology described the ritual. Three fields have been circling the thing I keep writing around for thirty years, none of them reads the others, and all three treat the time you were gone as empty.
In 2005 Gloria Mark and two colleagues at UC Irvine shadowed twenty-four information workers for a little over twenty-five hours each and wrote down everything they did. Not what they said they did. What they did, with a stopwatch.
The average stretch on one piece of work before a switch or an interruption was eleven minutes and four seconds. More than half of those stretches, 57.1 percent, ended in an interruption rather than a choice. When interrupted work was picked up again the same day, which happened about three quarters of the time, the average gap before returning was twenty-five minutes and twenty-six seconds, with 2.26 other pieces of work handled in between.
You have probably read a different number. “Twenty-three minutes and fifteen seconds to refocus” is attributed to Mark in roughly every productivity article of the last fifteen years. It is not in the 2005 paper. It is not in her 2008 paper either. The earliest place anyone has traced it to is a Gallup interview from June 2006, and even there it does not mean what the articles say it means. Nobody measured how long it takes to refocus. They measured how long it took to come back, during which the person was doing two other things. The distinction matters, and I will get to why.
the unit
The number is not the interesting part of that paper. The unit is.
Mark did not measure tasks. The year before, she and Victor González had watched the same kind of workers and concluded that “task” was the wrong size. People did not organize their day around tasks. They organized it around what the two of them called working spheres: a set of related events sharing a motive, a project, a customer, a responsibility. Their informants juggled about ten a day. The 2005 paper counted 11.7.
That is the closest anyone in the literature has come to saying the thing I said in a four-sentence post in 2019: that the switch that costs you is not between two tasks but between two worlds, “two customers, two distinctly different IT technologies, two different tool-sets.” A working sphere is an organization as it lives in one person’s day. They named it in 2004 and then measured how often it was interrupted. Nobody built anything with the name on it.
what the lab knows
The psychology is older and smaller. In 1995 Rogers and Monsell sat people in front of a screen and had them alternate between two trivial rules, odd-or-even and consonant-or-vowel, on a predictable schedule. Switch trials were slower and sloppier. Giving people time to prepare helped, but even with 1.2 seconds of warning a residual cost remained that only went away once the actual stimulus arrived. You cannot fully switch in advance. You switch when the work shows up.
A year earlier, Alan Allport and colleagues had proposed why: task-set inertia. The old task does not leave when you stop doing it. It lingers, active, interfering with the new one. Sophie Leroy took that into an office setting in 2009 and called it attention residue. Her finding has a detail that gets lost in the retelling. Merely finishing the prior task was not enough to clear the residue. Finishing it under time pressure was. Which anyone who has ever closed out a customer ticket at 4:55 on a Friday and felt the room change already knew.
So the lab says the switch costs a few hundred milliseconds and the previous world does not go quietly. The field says you get eleven minutes and then you are gone for twenty-five. And the trend runs one way. Mark’s screen-logging studies, collected in her 2023 book, put the average time on a single screen before switching at about two and a half minutes in 2004, seventy-five seconds in 2012, and forty-seven seconds between 2016 and 2021.
what the sociologists described
Here is the field nobody in software reads.
In 2000 Blake Ashforth, Glen Kreiner and Mel Fugate published a paper in the Academy of Management Review called “All in a Day’s Work: Boundaries and Micro Role Transitions.” Their subject is the ordinary movement between the roles a person holds: parent, employee, church member, friend. They put every role on a line from segmented to integrated. Segment hard and each crossing is clean but expensive, so people invent rites of passage to pay for it: the commute, the change of clothes, the drink. Integrate and the crossings are cheap but everything blurs, so you are doing “boundary work” all day to keep the roles from bleeding into each other.
Four years before that, the sociologist Christena Nippert-Eng had spent time with the staff of a research laboratory and watched how they carried the boundary. Segmentors had two key rings, two calendars, two wallets. Integrators had one of each. Sue Campbell Clark, in 2000, gave the person doing this a name, the border-crosser, and the people on each side who police the line, border-keepers.
Read that as a systems person and it is a description of the multi-organization problem with the technology removed. Two key rings are colored tools. The commute is a context switch with a fixed cost you agreed to pay. The integrator with one calendar is a person running six organizations on one inbox. The sociologists got there in 2000, four years before HCI named the working sphere, and I have not found a paper in the software lineage that cites them.
three fields, one object
Line them up and they are looking at the same thing at three magnifications.
Psychology’s unit is the rule, and its timescale is milliseconds. HCI’s unit is the working sphere, and its timescale is minutes. Sociology’s unit is the role, and its timescale is years. Each has a word for the world you are in. None of them has a word for the between.
For the psychologist the between is a blank screen with a fixation cross on it. For Mark it is the 2.26 intervening spheres, the traffic you handled while you were away. For the sociologist it is the commute, a ritual whose job is to be over. All three treat the time you are not in a world as a gap: a cost to be measured on the way through, or a rite to be performed, and then you are back.
That is the mistake, and it is the reason the twenty-three-minute number was never what people thought. Nobody in any of these fields has measured what a working sphere costs to come back to after a week. Mark’s outer bound is “same day.” The lab’s is 1.2 seconds. The sociologists measure crossings, not absences. The one quantity that decides whether six organizations is survivable, the rate at which an untouched world decays, has never been on anyone’s stopwatch.
In 2020 I put it in two sentences: being away from a project costs more the longer you are away from it. Mind bit-rot. I did not know then that I was pointing at the hole in three literatures.
Eleven minutes and four seconds is how long you get. Twenty-five minutes and twenty-six seconds is how long it takes to come back the same day. Nobody knows the number for a month, because every field that could measure it treats the time you were gone as empty. It is not empty. It is where the bill gets written.