The Myth of Multitasking
What we experience as 'doing several things at once' is actually rapid switching of attention between tasks — and every switch carries a measurable, cumulative cognitive cost.
Number of studies
1
Safety
High
Time to effects
Not applicable — this is a cognitive phenomenon describing the limits of attention, not an intervention.
Who it's for
Table of contents
TL;DR
What we experience as 'doing several things at once' is actually rapid switching of attention between tasks — and every switch carries a measurable, cumulative cognitive cost.
- →Awareness of the real cost of switching attention helps plan work requiring concentration more effectively
- →Justifies practical strategies such as blocking time for deep work without distractions
| Phenomenon type | A cognitive limitation — the brain switches attention, it does not process in parallel |
|---|---|
| Level of evidence | Strong — consistent results across many independent studies in cognitive neuroscience |
| Target group | People working on tasks requiring deep concentration |
| Key concept | Task-switching cost |
| Exception | Heavily automated tasks don't compete for the same attentional resources |
| Status | A well-documented cognitive phenomenon |
Understand
Overview
Multitasking, understood as simultaneously performing several cognitively demanding tasks, is largely an illusion — research in cognitive neuroscience consistently shows that the brain does not process two tasks requiring conscious attention in parallel, but rather switches rapidly between them, which carries a measurable time and quality cost with every switch. The exception is heavily automated tasks (e.g., walking and talking), which don't compete for the same limited attentional resources.
A study by Ophir and colleagues, one of the most frequently cited in this area, produced a particularly surprising result: people who identified as 'heavy multitaskers,' regularly using multiple media at once, performed worse, not better, on tasks requiring filtering out irrelevant information and switching tasks compared with people who practiced multitasking less often — challenging the popular belief that frequent practice of multitasking 'trains' the brain to handle it better.
Who can genuinely benefit from this? Anyone working on tasks that require deep concentration, for whom awareness of the real cost of switching attention (e.g., between work and phone notifications) can be an argument for more deliberate time management — blocks of focused work on a single task, instead of splitting attention across several at once.
Mechanism of action
Conscious attention and working memory, crucial for performing cognitively demanding tasks, are limited resources located mainly in the prefrontal cortex, which is unable to fully handle two independent, demanding information streams at the same time. When we try to 'do two things at once,' the brain actually rapidly switches attention back and forth — this process requires time to reorient to the context of each task after switching, which is the source of the so-called task-switching cost.
Importantly, research suggests that people who regularly practice media multitasking do not develop a better ability to filter out irrelevant stimuli — on the contrary, they show greater susceptibility to distraction by irrelevant information on some tests, suggesting that frequent multitasking may weaken, rather than strengthen, the ability to maintain focused attention on a single task.
Limited capacity of the prefrontal cortex
Conscious attention and working memory are limited resources, unable to fully handle two independent tasks at once.
Rapid switching instead of parallel processing
What we experience as multitasking is actually rapid switching of attention.
Cost of reorientation
Every switch requires time to reorient to the context of the task.
Evidence: strong — based on 1 study in this database.
Benefits
Common myths
MythRegularly practicing multitasking 'trains' the brain to handle it better.
FactStudies have shown that people who frequently practice media multitasking perform worse, not better, on tests requiring filtering out irrelevant information and switching tasks.
MythSome people are simply 'good at multitasking,' unlike others.
FactDespite some people's subjective belief in their own effectiveness at multitasking, objective cognitive tests rarely confirm that these people actually incur a smaller task-switching cost.
Forms & variants
The Myth of Multitasking comes in several forms that differ in bioavailability and use case — the form you pick genuinely matters for how effective the supplementation is.
Simultaneous multitasking
An attempt to literally perform two demanding tasks in parallel.
Best for: Not effective for tasks requiring conscious attention
Automated tasks
Activities that don't require conscious attention, like walking.
Best for: Can be combined with other tasks without a significant cognitive cost
Practice
Frequently asked questions
Only if at least one of the activities is heavily automated and doesn't require conscious attention — two tasks requiring conscious thought almost always compete for the same limited cognitive resources.
Available data don't suggest permanent damage, but regular, frequent media multitasking is associated in studies with a reduced ability to filter irrelevant information and maintain focused attention.
Practical strategies include blocking dedicated time for a single task without distractions (e.g., turning off notifications) and grouping similar tasks together instead of frequently jumping between different types of work.
What to combine with
Good combinations
Sleep and Memory — Both multitasking and sleep deprivation negatively affect the ability to consolidate information and maintain attention
Safety
Side effects & contraindications
Possible side effects
Contraindications
No significant contraindications at typical doses.
Is it worth taking?
Who it's for
- People working on tasks that require deep concentration
- People who want to understand the real cost of frequently switching between tasks and notifications
Not for
- No significant contraindications at typical doses.
Evidence
Worth knowing
Task-switching cost is measurable in laboratory studies as increased reaction time and more errors after each switch.
Heavily automated tasks, like walking, don't compete for the same attentional resources as tasks requiring conscious thought.
Studies
People who regularly practiced media multitasking performed worse, not better, on tasks requiring filtering out irrelevant information, compared with people who practiced multitasking less often.
Ophir E, Nass C, Wagner AD, Proceedings of the National Academy of Sciences, 2009
Cognitive control in media multitaskers
Strong evidenceOphir E, Nass C, Wagner AD · Proceedings of the National Academy of Sciences · 2009
A study showing that people who regularly practice media multitasking perform worse on tests requiring filtering out irrelevant information and switching tasks.
View studySources & bibliography
Citations are illustrative for this demo version and require full bibliographic verification by the editorial team before production publication.
Compare with similar entries
About the authors of this entry
Author
Michał NowakClinical Dietitian
Michał specializes in metabolic nutrition, intermittent fasting and sports supplementation.
61 publications on this site
Medical review
dr Anna KowalczykEditor-in-Chief, Molecular Biology
Anna oversees the editorial process and scientific review of every publication in the knowledge base. She previously researched autophagy and mitochondrial biology.
50 publications on this site
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Comments (2)
- KW
Kasia W. 2 weeks ago
Very clearly explained, especially the interactions section — I hadn't seen it laid out this well anywhere else.
- MT
Marek T. a month ago
Are you planning to update this with the newest study from this year? I saw an interesting meta-analysis.