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Why the Boundaries Between Tasks Matter: Event Segmentation and Memory

You do not live a workday as one continuous stream. You live it as a call, then the inbox, then a spreadsheet, then lunch — and nobody taught you where to cut. Psychologists call the cutting event segmentation. Research going back to the 1970s suggests the cuts do real work: they shape what is kept, what is filed together, and what comes loose in between.

By comun.ai · 12 October 2026 · ~6 min read

The mind cuts the day into events

The standard measure traces to Darren Newtson's 1973 study of how people divide ongoing behaviour into units.¹ The task: watch an activity and mark each point where one meaningful unit ends and the next begins. Later researchers report that observers tend to agree about where those points fall.⁴

Nobody has to be asked. Christopher Kurby and Jeffrey Zacks's review concludes that segmentation seems to be an ongoing part of everyday perception, running at several timescales at once, with small events grouped inside larger ones.³ A brain-imaging study led by Christopher Baldassano found similar structure with no marking task: as people followed a continuous narrative, their brain activity moved through stable patterns, and the shifts between them could be detected without annotating the story first.¹² Strong

Why there? Event segmentation theory says perception is always predicting what happens next, and a boundary is perceived when those predictions briefly fail. The cues include inferences about what a person is trying to do.² That is a theory, not a settled mechanism, but it suggests why a change of goal — closing one task, opening another — is a natural place for a cut.

What sits at a boundary is kept

Khena Swallow, Jeffrey Zacks and Richard Abrams showed people film clips of goal-directed activity in which objects appeared. Five seconds after an object was shown, the clip paused for a recognition test. Objects that were on screen when an event boundary occurred were recognised better than other objects.⁴ Moderate On that evidence the boundary is not dead time; it is one of the better-recorded moments in the stream.

What spans a boundary comes apart

The same cut has a cost. Youssef Ezzyat and Lila Davachi had people read stories in which some sentences began "A while later…" — a boundary — and others "A moment later…". Afterwards, memory for the link between two pieces of information was weaker when a boundary fell between them than when both sat inside one event.⁵ Sarah DuBrow and Davachi found the same for sequence: people remembered the order of items better within a stretch of shared context than across a shift in context.⁶ Moderate

Kurby and Zacks relate segmentation to the updating of working memory,³ and Swallow's team read their own more complicated results the same way.⁴ A boundary is double-edged: the moment itself is well recorded, and the thread back to what came before is where things loosen.

This is separate from switch costs and attention residue, which concern how you perform on the next task. This is about what the day leaves behind.

The doorway story, with its caveats put back

The popular version is "walking through doorways causes forgetting", the title of a 2006 paper by Gabriel Radvansky and David Copeland. People carried objects from room to room in a virtual space, and information about an object was less available after they had moved into a new room.⁷ A 2011 follow-up reported it again, including in real rooms.⁸

In 2021 Jessica McFadyen and colleagues set out to conceptually replicate it across four experiments using virtual reality, video and real movement. They observed no significant effect of doorways on forgetting. The one exception came when people were also carrying a working-memory load, and it showed up as more false alarms on the memory test. Their conclusion: the findings call into question how robust and general the effect is.⁹ Contested Not debunked, and not a law of rooms either.

Does paying attention to boundaries help?

Two findings point that way. Jesse Sargent and colleagues had 208 adults aged 20 to 79 segment films of everyday events and then try to remember them. How well a person segmented predicted how much they remembered, over and above tests of general cognitive ability, and as strongly in older adults as in younger ones.¹⁰ Moderate That is a correlation, not a cause.

Shaney Flores and colleagues tested it directly. Across five experiments, people watched films of everyday activity while trying to remember them; some also pressed a button whenever one meaningful event ended and another began. Those who marked the boundaries remembered more at delays from 10 minutes to one month, though not when tested immediately.¹¹ Early One paper, one lab, and films of other people doing things. Nobody was segmenting their own working day.

What this suggests for a line between tasks

A change of goal is the kind of change the theory says produces a boundary. If that holds for your own work, the seam between two tasks is both a well-recorded moment and the point where the thread to the last task loosens. A line written there marks the boundary on purpose and carries something across it.

Now the limit, stated plainly. Every study above used films, stories, lists of items, or rooms. None involved writing anything down, and none followed people through their own work. Whether writing a line at a task boundary improves memory, or work, has never been tested. The step from this research to that practice is our inference.

Where the evidence stands

What this means for this app

The calibrated one-sentence version: the mind cuts the day into events on its own and memory is organised around the cuts, so a line written at a cut is a reasonable way to mark one — and a way nobody has yet put to a test.

In this app the timestamp is automatic and one line is a complete entry, so the day reads back as the boundaries you chose to mark. Those are the changes an end-of-day memory is rebuilt from (see Where Did the Day Go?); for days with no obvious seam, try What to Write When Nothing Happened. This is reflection, not treatment. More on our science page, how your notes stay private on our privacy page, and the method itself in the interstitial journaling guide.