David Allen was driving between client meetings in Southern California in 1983 when he started sketching the outlines of what would become Getting Things Done, the productivity system that would later be widely recognized as a landmark in personal productivity literature. Allen had spent years as a management consultant, and he had noticed something strange: the most senior people he worked with were not failing because they lacked intelligence or discipline. They were failing because their minds were jammed with unfinished commitments — pick up the dry cleaning, call back the regional VP, draft the merger memo, remember the daughter’s recital — all clattering around the same mental space they needed for actual thinking.
Allen’s bet, eventually published in his 2001 book Getting Things Done: The Art of Stress-Free Productivity, rested on a single neurological premise. The brain is built for generating ideas, not for storing them. Every task you try to keep in your head consumes a slice of working memory, and working memory is the most expensive real estate in the human nervous system.
The consultant who watched executives drown in their own commitments
Allen was not a neuroscientist. He had worked diverse jobs before becoming a consultant. What he brought to the productivity question was the eye of someone who had watched smart people fail at organising themselves from a dozen different angles.
The pattern he kept seeing was the same. A vice president would walk into a meeting having silently rehearsed, for the third time that morning, the fact that he needed to call his accountant. The rehearsal was using cognitive bandwidth. The accountant would not be called any sooner. And the meeting he was actually in was getting half of him.
Allen called these clutched obligations “open loops.” His core claim was that the mind treats every unresolved commitment — from “finish the quarterly report” to “buy batteries” — with roughly the same low-grade urgency, and it will keep prodding you about them until they are either done or captured somewhere the brain trusts.
Working memory is a tiny, expensive room
The neurological premise Allen built on has, in the decades since, been mapped out in considerable detail. Working memory is the cognitive scratchpad that holds the information you are actively manipulating — a phone number you just heard, the sentence you are mid-way through writing, the three steps of the math problem in front of you. It is small, fragile, and easily flooded.
Research from the University of Kansas published in 2025 found that targeted interventions for working memory measurably improved word-problem solving in students with math difficulties, underlining how directly working memory gates higher reasoning. When the scratchpad is full of unprocessed obligations, the parts of cognition that depend on it — planning, problem-solving, reading comprehension — degrade in lockstep.
A piece in Psychology Today on lightening cognitive load describes how modern life routinely asks the brain to track more open items than it was designed to hold, and how performance falls off a cliff once that ceiling is breached. Allen had intuited the same ceiling from the consulting side of the desk.
The five steps Allen wrote on hotel notepads
The method itself is unfussy. Allen broke it into five moves: capture, clarify, organise, reflect, engage. Capture meant getting every open loop out of the head and into a trusted external system — a notebook, an inbox, a list. Clarify meant deciding what each item actually was: a next action, a project, a reference, a someday-maybe. Organise meant putting it where it belonged. Reflect meant reviewing the whole system weekly. Engage meant actually doing the work, freed from the background noise of forgetting.
The famous two-minute rule sat inside step two. If clarifying an item revealed it would take less than two minutes to finish, you did it immediately, because filing it would cost more cognitive overhead than just executing it. Allen’s clients found this almost embarrassingly effective. The drag was never the task. It was the negotiation about the task.
Why the brain keeps nagging you about batteries
The reason an unfinished errand can interrupt a strategy session has to do with how the brain flags incomplete tasks. This phenomenon, known as the Zeigarnik effect, describes how incomplete tasks remain accessible in memory while completed ones fade. Open loops stay loud. Closed ones go quiet.
Allen’s contribution was to weaponise this. If the brain nags you about anything unresolved, the move is not to nag back. The move is to convince the brain that the item is being tracked elsewhere, reliably, with a defined next action. Only then does the nagging stop and the working-memory room clear out.
Strategies for building this kind of external scaffolding — checklists, calendars, written next-action lists — are what therapists now recommend to clients with ADHD and executive-function challenges. A recent Psychology Today piece on boosting working memory recommends offloading commitments onto external tools precisely because the brain treats remembered intentions as ongoing tasks. Allen had been telling Fortune 500 executives the same thing two decades earlier, in slightly more expensive language.
The mind like water metaphor
Allen borrowed from his martial arts background to describe the goal state. He called it “mind like water” — a mind that responds to whatever hits it with exactly the appropriate force, no more and no less, then returns to stillness. A pebble produces ripples proportional to the pebble. A boulder produces ripples proportional to the boulder. Neither produces lingering chop.
The opposite, in Allen’s framing, was the typical knowledge worker walking into a Monday: a mind already churning from 200 unresolved items, where every incoming email is a stone dropped into water that was never calm to begin with. Performance suffers. So does sleep. So does the ability to enjoy the dinner you are eating, because part of your brain is still rehearsing Tuesday.
The Silicon Valley adoption that nobody predicted
When the book came out in 2001, Allen expected an audience of executives and managers. Instead, it was picked up — almost evangelically — by software engineers and early product managers in San Francisco. The GTD methodology spread through the Bay Area tech scene in the mid-2000s, particularly as technology-focused blogs and communities championed the approach. Wired ran a long profile in 2007. Programmers built GTD-shaped to-do apps; OmniFocus, Things, and Todoist all owe their information architecture to Allen’s list categories.
The engineering crowd took to it because the system was essentially a specification. Inputs in, decisions made, items routed to defined containers, weekly review as garbage collection. It treated the human operator as a processor with finite RAM, which is exactly what the neuroscience suggests the brain actually is.
What modern brain imaging has added
Since Allen’s book, imaging studies have given his premise more granular support. Sustained cognitive effort, the kind required to hold tasks in mind across a busy day, produces measurable fatigue in the prefrontal cortex. A review of training-load research aimed at first responders noted that cognitive fatigue impairs attention, decision-making, and reaction times in ways that compound over a shift — the operational version of the executive’s clogged Monday.
Other work has shown that anything that further degrades working memory makes the problem worse. A 2025 imaging study reported by Healio found that 63% of heavy lifetime cannabis users showed reduced brain activity during working memory tasks, a reminder that the scratchpad is biological hardware, vulnerable in the way all hardware is.
The corollary holds in the other direction too. Practices that reduce cognitive load — including, per recent neuroscience reporting, laughter and social bonding — improve the brain’s ability to think clearly under demand. Allen’s externalisation rituals do the same thing through a different door: not by boosting capacity, but by reducing what has to be held.
The trusted system, and why trust is the operative word
The part of GTD that practitioners most often get wrong is the weekly review. Allen was emphatic that the system only works if the brain believes the system. If you write items down in a notebook you never reopen, your subconscious clocks this within a week or two and resumes nagging you, because the external store has been revealed as a fiction. Trust is what allows the working-memory room to actually empty.
This is also why GTD tends to fail for people who try to adopt it casually. The neurology is unforgiving. You either have a complete, reviewed, current capture of your open loops, or you have most of your loops on a list and the rest still circulating in your head. The second state, Allen argued, is no better than no list at all — and arguably worse, because now you are paying maintenance costs on the list and still carrying the cognitive freight.
Forty years on, the premise has held
Allen is in his late seventies now, still teaching seminars, still asked the same question by every reporter who interviews him: does GTD still work in the age of Slack notifications and infinite-scroll inboxes? His answer has not changed. The volume of inputs has multiplied. The size of the human working-memory scratchpad has not. The math therefore points in the same direction it pointed in 1983, on a Southern California highway, between two consulting clients: the brain is for having ideas, not holding them, and anything you clutch is taxing the one part of you that you most need free.
