In our hyperconnected world, multitasking has become a badge of honor. We pride ourselves on responding to emails while attending virtual meetings, scrolling through social media while watching television, and toggling between a dozen browser tabs as we work. We’ve convinced ourselves that doing more things simultaneously makes us more productive, more efficient, and perhaps even more intelligent. But what if everything we believe about multitasking is wrong?
The science is unequivocal: multitasking, as we commonly understand it, is a myth.
Our brains are not designed to focus on multiple complex tasks at once, and when we attempt to do so, we’re not actually multitasking—we’re rapidly switching between tasks in a way that diminishes our performance, increases our stress, and ultimately makes us less productive than if we had focused on one thing at a time.
To understand why, we need to explore the fascinating science of cognitive load and how our brains actually process information.
Understanding Cognitive Load Theory
Cognitive load theory, developed by educational psychologist John Sweller in the late 1980s, provides a framework for understanding how our brains process and retain information. At its core, the theory recognizes that our working memory—the mental workspace where we consciously process information—has severe limitations.
Think of working memory as a small desk where you’re trying to complete various tasks. You can only fit so many papers, tools, and projects on that desk at once. When the desk becomes cluttered, your ability to work effectively diminishes. You spend more time searching for what you need, more items fall to the floor, and the quality of your work suffers.
Scientists have discovered that working memory can typically hold only about four chunks of information at any given time, and this capacity varies between individuals. This isn’t just a minor constraint—it’s a fundamental limitation of human cognition that affects everything we do. When we attempt to process more information than our working memory can handle, we experience cognitive overload, which impairs our ability to learn, reason, and make decisions.
Cognitive load comes in three distinct forms. Intrinsic load refers to the inherent difficulty of the material or task itself—learning quantum physics naturally demands more cognitive resources than learning to make a sandwich. Extraneous load is the unnecessary cognitive burden imposed by poor presentation or design—like trying to learn from a confusing textbook or navigate a poorly designed website. Germane load represents the mental effort dedicated to processing information and building long-term memory structures, which is the productive type of cognitive work we want to maximize.
The Multitasking Illusion
What we call multitasking is almost always task-switching—rapidly shifting our attention between different activities. This distinction might seem semantic, but it’s crucial to understanding why multitasking fails. True simultaneous multitasking is only possible when at least one of the tasks is so automatic that it requires virtually no conscious attention, like walking while talking or humming while cooking. But when both tasks require conscious thought and attention, the brain cannot process them simultaneously.
Neuroscientist Earl Miller from MIT has been particularly vocal about this reality. His research demonstrates that our brains are “not wired to multitask well.” When we think we’re multitasking, we’re actually engaging in sequential task-switching, and each switch comes with a cost. The brain must disengage from one task, reorient to the new task, and then fully engage with it—a process that happens so quickly we don’t consciously notice it, but which nonetheless consumes time and mental energy.
The switching costs are substantial. Research by psychologist David Meyer and colleagues has shown that switching between tasks can cost as much as 40% of someone’s productive time. When you switch from writing an email to checking a spreadsheet and back again, you lose several seconds each time your brain reorients itself. Over the course of a day filled with task-switching, these seconds accumulate into significant losses in productivity.
But the cost isn’t merely about time. Each switch also increases cognitive load, using up precious working memory resources. The brain must hold information about both tasks in working memory—where you were in the first task, what you need to do in the second task, and how to resume the first task afterward. This juggling act fills up our mental workspace, leaving less room for actually processing the tasks themselves.
The Neural Reality of Divided Attention
Neuroscience has given us unprecedented insight into what happens in the brain when we attempt to multitask. Functional MRI studies have revealed that when people perform two tasks simultaneously, neither task receives the full neural resources it would receive if performed alone. The brain shows reduced activation in regions critical for each task, resulting in diminished performance on both.
Research by René Marois at Vanderbilt University has identified a specific bottleneck in the brain called the “response selection” stage. This is where the brain chooses which action to take based on sensory input. This bottleneck can only process one task at a time, creating a fundamental limitation to multitasking. When two tasks compete for access to this bottleneck, one must wait, regardless of how skilled or practiced we are at those tasks.
The prefrontal cortex, our brain’s executive control center, plays a crucial role in task management. When we switch between tasks, the prefrontal cortex must reconfigure itself for each new task, updating the rules, goals, and procedures relevant to what we’re currently doing. This reconfiguration isn’t instantaneous—it takes time and energy, further compounding the costs of multitasking.
Even more concerning is what happens to our ability to encode memories when we multitask. Studies by Russell Poldrack at Stanford have shown that learning while multitasking results in information being processed differently in the brain, often being routed to the striatum (associated with procedural memory) rather than the hippocampus (associated with declarative memory). This means that information learned while multitasking may be less flexible and harder to recall in different contexts.
The Performance Penalty
The empirical evidence against multitasking is overwhelming. Study after study demonstrates that attempting to do multiple things at once leads to more errors, slower completion times, and poorer quality work. A landmark study published in the Journal of Experimental Psychology found that participants took significantly longer to complete tasks when they had to switch between them compared to when they completed them sequentially.
Perhaps nowhere is the danger of multitasking more evident than in driving. Despite laws and public awareness campaigns, many people continue to use their phones while driving, convinced they can manage both tasks safely. The statistics tell a different story. The National Safety Council reports that cell phone use while driving leads to 1.6 million crashes each year. Texting while driving makes a crash up to 23 times more likely. These aren’t just statistics—they represent real lives lost because of the multitasking myth.
Cognitive psychologist David Strayer has extensively studied distracted driving, and his research reveals something disturbing: even hands-free phone conversations significantly impair driving performance. The problem isn’t just physical—it’s cognitive. When we’re engaged in a phone conversation, our mental resources are divided, and we’re less likely to notice hazards, respond quickly to changing conditions, or maintain awareness of our surroundings. Our eyes may be on the road, but our attention isn’t.
In the workplace, chronic multitasking has been linked to increased stress, decreased job satisfaction, and higher error rates. A study by researchers at the University of California, Irvine found that workers who were constantly interrupted and forced to multitask experienced higher stress levels, frustration, and time pressure. They also found that it takes an average of 23 minutes and 15 seconds to return fully to a task after an interruption—far longer than most people realize.
The Addictive Nature of Task-Switching
If multitasking is so detrimental, why do we keep doing it? Part of the answer lies in our brain’s reward system. Each time we switch tasks—checking our email, glancing at a notification, refreshing social media—we get a small hit of dopamine, the neurotransmitter associated with reward and pleasure. This creates a feedback loop that makes task-switching feel good in the moment, even as it undermines our productivity and cognitive performance.
This dopamine-driven behavior helps explain why resisting the urge to check our phones or switch tasks can feel so difficult. We’re not just fighting a bad habit; we’re fighting our brain’s reward circuitry. The immediate gratification of task-switching often overshadows the longer-term benefits of sustained focus, much like how the immediate pleasure of eating candy can override our knowledge that it’s not healthy.
Technology companies understand this psychology all too well. Many apps and platforms are specifically designed to encourage frequent checking and task-switching, with notifications, badges, and other features that trigger our dopamine response. While these design choices benefit companies by increasing engagement, they come at a cost to our cognitive performance and mental well-being.
Strategies for Managing Cognitive Load
Understanding the limitations of our working memory and the myth of multitasking points toward better strategies for managing our cognitive resources. The key is to work with our brain’s natural strengths rather than against them.
Single-tasking, or monotasking, is the practice of dedicating full attention to one task at a time. This doesn’t mean you can’t do multiple things throughout the day—it means you do them sequentially rather than simultaneously. Research consistently shows that single-tasking leads to faster completion times, fewer errors, and better quality work than multitasking.
Time-blocking is another effective strategy. By scheduling specific blocks of time for different tasks and protecting those blocks from interruption, you can minimize task-switching and give your brain the sustained focus it needs for deep work. During these blocks, eliminate distractions by silencing notifications, closing unnecessary browser tabs, and setting boundaries with colleagues.
The Pomodoro Technique, which involves working in focused 25-minute intervals followed by short breaks, aligns well with what we know about cognitive load. These focused periods allow for sustained attention without overwhelming working memory, while the breaks provide opportunities for mental recovery and consolidation.
Reducing extraneous cognitive load is equally important. This means organizing your environment, simplifying your tools and processes, and removing unnecessary complexity from your tasks. A cluttered desktop, both physical and digital, increases cognitive load by forcing your brain to filter out irrelevant information. A clean, organized workspace makes it easier to maintain focus.
The Path Forward
The science is clear: our brains are not built for multitasking. Working memory is limited, task-switching is costly, and attempting to do multiple complex tasks simultaneously reduces our performance on all of them. This isn’t a personal failing or a skill that can be improved with practice—it’s a fundamental characteristic of human cognition.
Accepting this reality isn’t about admitting defeat; it’s about working smarter. By understanding cognitive load and abandoning the multitasking myth, we can make better decisions about how we work, learn, and live. We can design our days to support sustained focus rather than constant distraction. We can create environments that minimize cognitive overload rather than maximize it.
In a world that constantly demands our attention and glorifies busyness, choosing to focus on one thing at a time is an act of rebellion. It’s also an act of self-care and a path to better performance, lower stress, and higher quality work. The science has spoken: if you want to do your best work, stop trying to do everything at once.
Our brains are remarkable organs capable of extraordinary things, but they work best when we respect their limitations. By embracing single-tasking, managing our cognitive load, and rejecting the multitasking myth, we can unlock our true cognitive potential and accomplish more by trying to do less simultaneously. In the end, the tortoise had it right all along: slow and steady, focused and deliberate, wins the race.
