Originally published in April 2016 and comprehensively updated and edited in June 2026.
The science of multitasking reveals it degrades accuracy, creativity, and focus. A decade of research explains why doing less at once produces more.
The email is half-written. The spreadsheet is open in another tab. A colleague has just appeared in the doorway with a question that will only take a second. The phone is face-up on the desk, showing a calendar reminder for a meeting that starts in eleven minutes. Somewhere in the background, a group chat is generating notifications at the rate of roughly one every forty seconds.
This is not an unusual morning. For many people working in offices — or from home, where the boundaries are even softer — it is simply Tuesday. The cultural assumption underlying all of it is that a capable, productive person handles many things at once. That the ability to juggle is a professional virtue. That doing one thing at a time is a luxury, or perhaps a sign of limited ambition.
The science, accumulated steadily over the past three decades and now quite robust, tells a different story. Multitasking — at least the kind that involves switching between cognitively demanding tasks — does not make people more productive. It makes them less accurate, slower, more error-prone, and over time, measurably worse at the sustained thinking that most demanding work actually requires. Understanding why this is true, and why it took so long for the gap between cultural belief and scientific evidence to narrow, is a story about attention, identity, technology, and the particular pressures of early twenty-first century work culture.
The Myth That Became a Job Requirement
The word “multitasking” did not originally describe human behavior. It was a computing term, coined in the 1960s to describe a processor’s ability to handle multiple programs by switching between them rapidly — so rapidly that to an observer it appeared simultaneous. The term migrated into descriptions of human behavior sometime in the 1990s, gaining momentum through the decade as personal computers became workplace fixtures and the pace of information exchange accelerated.
By the early 2000s, multitasking had been thoroughly absorbed into the vocabulary of workplace competence. It appeared in job listings as a desired skill. It surfaced in performance reviews as evidence of capability. The ability to manage many things at once was understood not just as useful but as a marker of intelligence and professional value. Saying you were good at multitasking was, in many work environments, nearly equivalent to saying you were good at your job.
What is striking, in retrospect, is how little this cultural consensus had to do with evidence. The research that would eventually challenge it had been accumulating for years, largely in academic journals that few hiring managers read. The gap between what science was finding and what offices were assuming would take years to close — and in some workplaces, it has not fully closed yet.
What the Brain Is Actually Doing
The first thing to understand about multitasking is that, for most cognitively demanding tasks, the brain does not actually do it. What feels like simultaneous processing is almost always rapid sequential switching — the brain moving back and forth between tasks rather than running them in parallel.
This distinction matters because each switch carries a cost. Psychologists call it the task-switching cost, and it has been studied in controlled laboratory settings since at least the 1990s. The basic finding is consistent: when people switch from one task to another, their performance on the new task is temporarily degraded. Reaction times slow. Error rates rise. The effect is most pronounced when the two tasks are dissimilar and when the switch is abrupt rather than planned.
David Meyer and colleagues at the University of Michigan, whose work on this phenomenon was influential in the early 2000s, identified two components of the switching cost. The first is the time required to disengage the mental rules governing the old task — what researchers call the “task set” — and activate the rules for the new one. The second is a period of lingering interference, in which the old task set continues to compete for cognitive resources even after the switch has nominally been made. Together, these two components can add up to significant lost time and increased errors, even when each individual switch seems trivially fast.
The Illusion of Simultaneous Processing
There is a narrow class of tasks that humans genuinely can perform simultaneously — typically one that is automatic and highly practiced, paired with one that requires active attention. An experienced driver can hold a simple conversation while navigating a familiar route. A trained pianist can discuss their weekend plans while playing scales. But these are not the combinations most people have in mind when they describe themselves as good multitaskers. The combinations that matter in knowledge work — writing while reading, composing an email while listening to a presentation, analyzing data while fielding questions — consistently show performance degradation under conditions of divided attention.
A useful way to think about it is in terms of bandwidth. Attention is not unlimited. When two tasks both require significant cognitive bandwidth and compete for the same mental resources — language processing, logical reasoning, working memory — neither gets full capacity. The result is that both are done worse than either would be if performed alone. The person believes they are being efficient. The output tells a different story.
The Heavy Multitasker Problem
In 2009, a team of researchers at Stanford University published a paper that generated considerable attention, in both academic circles and the popular press. Clifford Nass, Eyal Ophir, and Anthony Wagner set out to identify what advantages heavy multitaskers might have that would explain their preference for doing many things at once. The results were not what they expected.
The researchers compared people who frequently engaged in media multitasking — consuming multiple streams of media simultaneously, switching frequently between tasks and devices — with people who did so rarely. They tested both groups on a battery of cognitive measures: the ability to filter out irrelevant information, the capacity to manage working memory, and the speed of task switching itself.
The heavy multitaskers performed worse on all three. They were more susceptible to distraction from irrelevant stimuli. They held more information in working memory than they needed to, including information that was not useful for the task at hand. And — most counterintuitively — they were slower to switch between tasks than the light multitaskers were. The people who multitasked most were, by measurable cognitive criteria, worst at it. Subsequent research has debated the magnitude and generalizability of these findings, but the study remains influential because it helped redirect attention toward the cognitive costs of chronic media multitasking.
Nass, reflecting on the findings in interviews before his death in 2013, described the heavy multitaskers as having a fundamentally different relationship with information — one in which everything felt potentially relevant, and nothing could be safely ignored. That inability to filter is not a cognitive strength. It is a vulnerability. The mind that cannot dismiss irrelevant information is a mind that will always be pulled in more directions than it can usefully go.
Why Heavy Multitaskers Keep Multitasking
If heavy multitasking degrades performance, why do people who do it frequently continue — and often report feeling productive while doing so? The answer involves a mismatch between subjective experience and objective output that runs through much of the research on divided attention.
Multitasking tends to feel engaging. The frequent switches between tasks create a sense of novelty and momentum. Responding to an email in the middle of a longer project provides a small, immediate sense of completion — the kind of satisfaction that the longer project, with its deferred reward, cannot offer in the moment. The brain’s reward circuitry responds to these small completions in ways that reinforce the behavior regardless of whether the overall work is going well.
There is also the matter of busyness as a signal. In many professional environments, visible activity — responding quickly, always having multiple windows open, never being unreachable — reads as competence and dedication. The feeling of doing many things is, in these cultures, reinforcing independent of the quality of what gets done. This is not a character flaw. It is a rational response to environments that reward the appearance of productivity over its substance.
Gender, Myth, and the Multitasking Stereotype
Any honest account of multitasking’s cultural history has to address the persistent popular belief that women are inherently better at it than men. The claim circulated widely in the 2000s and 2010s, repeated in magazine articles, management seminars, and casual workplace conversation with a confidence that suggested settled science.
The actual research is considerably more ambiguous. Some studies have found small differences favoring women on certain types of task switching, particularly those involving rapid shifts between well-defined, relatively simple tasks. Others have found no significant difference. The tasks used in these studies often differ enough from each other — and from real-world multitasking — that comparing results is difficult. Patricia Hirsch and colleagues at RWTH Aachen University published a large study in 2019 specifically designed to test the stereotype under controlled conditions and found no meaningful gender difference in multitasking performance.
What the stereotype does reflect, perhaps, is something real about the social distribution of multitasking demands rather than cognitive differences between groups. Women, and particularly mothers, have historically managed more simultaneous domestic and professional responsibilities than men on average. If women appear to multitask more effectively, one explanation consistent with the evidence is that they have had more practice navigating fragmented attention environments — not that their brains are wired differently. The stereotype may be tracking a social pattern and misattributing it to biology.
The Cognitive Cost Accumulates
Most discussions of multitasking focus on immediate performance degradation — the errors made, the time lost. Equally important, and somewhat less discussed, is what happens over longer time horizons when frequent task-switching becomes a habitual mode of working.
Sophie Leroy, a management professor at the University of Washington, developed the concept of attention residue to describe a phenomenon that the Stanford research had gestured at but not fully named. When you switch from Task A to Task B, part of your attention remains with Task A — especially if Task A was unfinished or particularly demanding. That residue is not imaginary. It is cognitive load that is not available for Task B. And if you are constantly switching before tasks are completed, you are constantly carrying residue from the previous task into the next one.
Over a full workday, the accumulation of attention residue means that almost nothing receives your full cognitive engagement. You might work for eight hours and yet never really be fully present for any of it. The output reflects this even when the subjective experience of busyness does not.
Leroy’s research also found that the negative effects of attention residue were significantly reduced when people were able to complete a task — or reach a natural stopping point — before switching. This suggests that the problem is not switching per se but interrupted switching: leaving tasks in an unresolved state creates a kind of cognitive open loop that continues to draw attention even after the switch has been made.
What Happens to Creativity
The effects of chronic multitasking on creative thinking deserve particular attention, in part because creativity is often the kind of output most resistant to measurement and therefore most easily overlooked in productivity discussions.
Creative insight — the kind that produces genuinely new ideas rather than competent recombinations of existing ones — appears to depend heavily on a brain state that multitasking disrupts. Neuroscientists have identified a network of brain regions, sometimes called the default mode network, that becomes active during periods of apparent rest or mind-wandering. This network is associated with making novel connections between disparate pieces of information, with perspective-shifting, and with the kind of associative thinking that precedes many creative breakthroughs.
The default mode network is suppressed during focused, externally directed task performance. But it is also suppressed — in a different and less productive way — during the fractured, reactive attentional state that heavy multitasking produces. A mind that is constantly switching between demands never fully enters either focused engagement or the productive wandering that generates insight. It occupies an intermediate state that is cognitively expensive but generatively thin.
Writers, researchers, designers, and others whose work depends on originality have described this experience in terms that predate the neuroscience by decades. The language changes — distraction, scattered thinking, inability to concentrate — but the phenomenon being described is consistent. The conditions that allow for genuine creative work are conditions of sustained, relatively uninterrupted engagement. Multitasking environments are almost definitionally hostile to them.
Technology’s Role in Normalizing Cognitive Fragmentation
It would be incomplete to discuss multitasking and cognitive degradation without examining how technology, and particularly workplace communication technology, both reflected and amplified the problem.
Email, which became a workplace staple through the 1990s, introduced the first wave of always-on communication expectations. Unlike a phone call, which required both parties to be available simultaneously, email created an asynchronous queue that nonetheless carried implicit expectations of timely response. As volume increased and response norms compressed, many workers found themselves cycling back to their inboxes every few minutes — not because each individual message required it, but because the ambient pressure to be responsive had become internalized.
Instant messaging platforms accelerated the dynamic further. Tools like Slack, Microsoft Teams, and their predecessors offered something email could not: the social texture of real-time conversation, with its cues of presence, availability, and immediate acknowledgment. They also introduced a new category of ambient demand — the sense that colleagues were watching for responses, that the green dot next to your name carried an implicit obligation, that silence in a channel might be read as inattention or disengagement.
Gloria Mark’s research at UC Irvine tracked how workers at technology companies actually spent their time in the mid-2000s and found that the average worker switched tasks roughly every three minutes — a figure that has shifted in subsequent studies as communication tools have multiplied, but not in the direction of improvement. Importantly, about half of those switches were self-initiated — the worker chose to move to something else before the current task was complete, rather than being pulled away by an external interruption. Technology had not just created new sources of interruption. It had cultivated habits of self-interruption that persisted even in its absence.
The Open-Plan Office as Multitasking Architecture
The physical design of workplaces during this period compounded the problem in ways that were rarely framed in cognitive terms. The open-plan office, which became the dominant workplace design in the 2000s and 2010s, was promoted on grounds of collaboration, spontaneity, and efficient use of space. Its effects on concentration received considerably less scrutiny.
Research on open-plan offices consistently found that workers in them experienced more interruptions, more difficulty concentrating, and higher levels of stress than workers in private offices or even cubicles. A 2018 study by Ethan Bernstein and Stephen Turban at Harvard Business School found, counterintuitively, that open-plan offices actually reduced face-to-face interaction — workers compensated for the loss of privacy by retreating into headphones and digital communication. The architecture designed to encourage collaboration was producing isolation mediated by screens, with all the attentional fragmentation that implied.
The person trying to do complex analytical work in a busy open-plan office in 2014 was not simply distracted. They were working in an environment that had been designed, largely without cognitive science input, in ways that were systematically hostile to the kind of focused thinking their work required.
The Cultural Resistance to Slowing Down
Understanding why the evidence about multitasking took so long to influence behavior — and why it still has not fully done so — requires looking at forces beyond cognition.
Part of the resistance was simply structural. Individual workers operate within systems that reward certain behaviors regardless of their actual productivity. If your organization values rapid responsiveness, turning off notifications and batching email into two daily sessions is a legitimate cognitive strategy that may also read as aloofness or poor communication. The rational individual calculus and the organizational signaling calculus point in different directions.
Part of it was also cultural, in a deeper sense. The early twenty-first century developed a particular relationship with busyness that was not just about workplace norms. Being busy — demonstrably, visibly busy, with many demands and little margin — had become a status signal in many social contexts. Saying “I’ve been absolutely swamped” carried a subtle social weight that “I had a fairly quiet week” did not. The former implied importance, demand, indispensability. The latter implied availability — which, in the professional culture of the period, could read as a polite way of saying you were not quite important enough to be needed. The sociologist Silvia Bellanca and others have traced what they call the “busyness as a badge of honor” phenomenon, noting that in contrast to earlier periods when leisure signaled success, contemporary professional culture had inverted this: time scarcity became the marker of importance. Doing one thing slowly and carefully looked, in this cultural context, like the behavior of someone who did not have enough to do.
Multitasking fit neatly into this framework. It was not just efficient; it was a performance of high demand and high capability. The fact that it degraded the quality of work was less visible than the fact that it signaled a full plate.
What Changed — and What Didn’t
By the late 2010s and into the 2020s, awareness of multitasking’s cognitive costs had migrated meaningfully from academic literature into mainstream conversation. Cal Newport’s Deep Work, published in 2016, synthesized much of the research for a general audience and argued that the capacity for sustained, undistracted focus had become both rarer and more economically valuable precisely because the conditions that produced it were being systematically eroded. The book found a large readership, which was itself a signal that something had shifted in how people were thinking about attention and productivity.
The COVID-19 pandemic, which forced a sudden transition to remote work beginning in 2020, did not resolve these pressures — it redistributed them. Working from home removed some sources of interruption while collapsing the boundary between work and domestic life in ways that introduced new ones. More significantly for the multitasking question, it intensified reliance on the communication platforms — Slack, Teams, Zoom — most associated with reactive, fragmented work styles. Many workers reported feeling more overwhelmed despite having more nominal control over their environments, a finding consistent with what the research would predict: the tools had moved with them, and the habits the tools had cultivated had moved with them too.
The research that has accumulated since 2016 has largely confirmed and extended the earlier findings rather than overturning them. The negative effects of multitasking on accuracy, recall, and creative output have been replicated across different populations and task types. There is some nuance around age, experience, and the specific nature of the tasks involved, but the basic conclusion — that doing two cognitively demanding things at once makes you worse at both — has held up well.
What has changed more significantly is the policy and design response. Some organizations have experimented seriously with asynchronous communication norms, meeting-free days, and explicit protections for blocks of uninterrupted work time. A small but growing number of companies have restructured their communication expectations in ways that treat sustained focus as a resource worth protecting rather than an indulgence. Whether these experiments will become mainstream practice or remain niche arrangements is still genuinely unclear.
There is also an emerging irony worth noting. The rise of generative AI has begun automating many of the routine, lower-stakes tasks that once filled the working day — drafting boilerplate, summarizing documents, formatting reports. What remains, increasingly, is the work that requires judgment, synthesis, and original thinking. That is precisely the category of work most vulnerable to chronic attentional fragmentation. If AI continues to raise the floor on routine output, the ceiling — the quality of the genuinely difficult thinking that machines cannot yet replicate — will depend more than ever on the capacity for sustained human attention. The research on multitasking suggests that capacity is not guaranteed. It has to be protected.
Conclusion: The Cost We Stopped Noticing
There is something worth sitting with in the gap between how multitasking feels and what it produces. It feels productive, engaged, responsive, capable. It produces work that is more error-prone, less creative, and often less satisfying to the person who made it. The mismatch is not incidental. It is part of what made the myth so durable.
The research on multitasking and cognitive degradation ultimately points toward something simple that is also, in practice, genuinely hard: quality attention is not infinitely divisible. When it is divided past a certain point, something real is lost — not just efficiency in the narrow sense, but the depth of engagement that makes difficult work possible and satisfying. The kind of thinking that solves hard problems, writes well, designs something original, or makes a sound judgment under uncertainty is thinking that requires more than fragments.
None of this means that managing multiple responsibilities is avoidable, or that the occasional interruption causes permanent harm. The research is about sustained patterns, not individual moments. It is about what happens to cognition when fragmented attention becomes the default mode rather than an occasional necessity.
What the evidence suggests is that the cultural equation of multitasking with productivity was, at its core, a confusion between activity and output. The two are related but not identical, and in cognitively demanding work they can diverge dramatically. The person doing one hard thing carefully is often producing more — and better — than the person doing five things simultaneously and calling it a full day.
That insight is not new. What is new is the neurological and psychological detail with which we can now describe exactly what is happening in the brain when the myth is put into practice.
The modern workplace spent decades treating divided attention as a sign of capability. The evidence increasingly suggests the opposite: in a world obsessed with doing more at once, the ability to focus on one thing may be the more valuable skill.
