The nuanced version is: multitasking is usually bad when it means doing cognitively demanding tasks simultaneously—but some forms of “multitasking” are perfectly fine, and the feeling of productivity is not entirely an illusion.
1. Your brain usually isn't doing two hard things at once
For tasks that require attention, working memory, language, reasoning, or decision-making, the brain has a limited attentional bottleneck.
So when you:
- write an email while listening to a meeting,
- study while checking messages,
- code while bouncing between Slack and a browser,
you're often switching between tasks, not processing both fully in parallel.
Each switch has a cost: you have to reorient yourself, retrieve the relevant context, and figure out where you left off. Those costs can be tiny individually but substantial over dozens or hundreds of switches.
2. But multitasking can feel remarkably productive
This is the interesting part.
You get frequent little hits of completion. Answering a message, checking something off, switching to another tab—each produces visible progress. Meanwhile, the harder task may produce very little visible output for several minutes.
So multitasking can create a psychological contrast:
“I answered five emails, checked the numbers, replied to Slack, and worked on the report.”
It feels like six things got accomplished simultaneously.
But the relevant question is often:
How much valuable work did I produce per hour, including the cost of all those transitions?
That number can be considerably worse than it feels.
3. Some multitasking really does work
There are at least three importantly different cases.
Automatic + demanding:
Walking while listening to a podcast. Driving on a familiar road while having a simple conversation (within safety limits). Folding laundry while listening to an audiobook.
These can coexist because one activity requires relatively little conscious processing.
Two complementary tasks:
Cooking while listening to music. Taking notes while listening to a lecture. These aren't necessarily competing for exactly the same mental resources.
Rapid switching among shallow tasks:
Processing routine email, administrative work, notifications, etc. Here, the performance penalty may be acceptable because none of the individual tasks requires much deep concentration.
The problem is particularly pronounced when both tasks demand the same limited cognitive resources.
4. Multitasking can occasionally be useful even when it's inefficient
Suppose you're stuck on a difficult problem. Switching to a routine task for ten minutes can give you a break and allow your mind to process the original problem in the background.
That's not necessarily productive multitasking. It's closer to deliberate alternation.
Likewise, having a few low-effort tasks available during natural downtime can be efficient. The mistake is assuming that because two activities can be interleaved, doing so continuously is optimal.
5. There's also a motivational advantage
Multitasking can make boring work more tolerable.
Checking messages between unpleasant tasks, listening to something while doing repetitive work, or alternating activities can provide stimulation and reduce the subjective feeling of effort.
So sometimes the tradeoff is:
slightly lower efficiency + substantially higher willingness to work.
That's not automatically a bad trade.
If the alternative is spending 45 minutes procrastinating because a task is painfully boring, interleaving it with something mildly rewarding might actually increase your total output.
The useful rule
Rather than “never multitask,” I'd use:
Protect attention for work that compounds; multitask when the tasks are automatic, complementary, or low-stakes.
Deep writing, learning, strategic thinking, difficult conversations, and complex problem-solving generally deserve uninterrupted attention.
Routine administration, household chores, commuting, exercise, and other relatively automatic activities are much better candidates for combining.
And perhaps the biggest trap is this:
Multitasking optimizes for the feeling of being busy. Single-tasking often optimizes for actually finishing something important.
