Multitasking requires rapidly switching between tasks and goals, taxing networks in our brains that support cognitive control and attention.
Research shows multitasking leads to poorer performance, known as switch costs, compared to focusing on one task at a time.
Certain types of multitasking like media multitasking are associated with reduced working memory, long-term memory, and abilities to sustain attention.
Key Facts:
- Multitasking involves frequently switching between tasks rather than truly doing them simultaneously.
- Key brain networks involved in cognitive control and attention determine multitasking ability.
- Multitasking leads to “switch costs” – reductions in performance speed and accuracy.
- Media multitasking is pervasive, especially among youth. Those who media multitask more heavily can perform worse on single task cognitive tests.
The Allure and Illusion of Multitasking
In today’s demanding world, multitasking has become ubiquitous.
As we strive to get more done in less time, we multitask by tackling two or more tasks at once or by rapidly switching between tasks.
This might mean texting while watching TV, jumping from writing a report to answering emails, or driving while talking on the phone.
However, scientific research reveals multitasking is an illusion – our brains actually cannot process two tasks simultaneously.
What we call multitasking involves rapidly shifting attention between tasks, not truly doing them in parallel.
Despite its impossibility, multitasking can feel rewarding or even addictive, providing a sense of productivity and stimulation.
But attempting to multitask has costs, reducing our performance across a myriad of cognitive tasks.
As revealed by neuroscience, multitasking places heavy demands on brain networks involved in cognitive control and attention.
Performance declines occur because these networks have limited capacity.
When divided, they operate less efficiently, leading to poorer focus, impaired working memory, and increased distractions.
The Brain Systems Strained by Multitasking
Functional MRI studies indicate key brain networks determine our ability to multitask.
These include the frontoparietal control network, dorsal attention network, and ventral attention network.
The frontoparietal network supports goal planning and identifying relevant information for achieving goals.
Multitasking requires representing distinct goals for separate tasks, demanding more from this network.
The dorsal attention network selects and focuses on relevant sensory information, whether external sights and sounds or internal thoughts, based on goals in the frontoparietal regions.
Multitasking divides this network across competing tasks.
Finally, the ventral attention network detects distracting stimuli, which can derail other tasks.
Juggling tasks leaves us more susceptible to task-irrelevant distractions.
Together, the increased loads but divided resources across these networks lead to multitasking impairments.
Their interactions become more complex across competing streams of information and goal representations.
The Cognitive Costs of Multitasking: Switch Deficits
Studies assessing the costs of switching between tasks reveal multitasking consistently reduces speed and accuracy, known as switch costs.
In lab experiments, participants take longer and commit more errors when alternating between tasks versus repeating the same task.
Neuroimaging shows frontoparietal and dorsal attention regions activate more strongly during task switches, reflecting greater demands on control and attention.
Maintaining task goals requires more effort after switching.
Despite the brain’s compensatory efforts, performance still suffers compared to staying on one task.
Aging further compounds switch deficits, as connectivity declines between brain networks supporting cognition.
For older adults, multitasking imposes even larger neurocognitive costs.
Intensive Media Multitasking
Given rising digital technology use, media multitasking has become extremely common, especially among youth.
Media multitasking entails engaging with multiple streams of media at once, like texting while watching Netflix or checking social media during class lectures.
Individuals vary substantially in their media multitasking.
Heavy media multitaskers (HMMs) frequently consume multiple media concurrently, while light media multitaskers (LMMs) focus on one medium at a time.
Intriguingly, HMMs seem to struggle more with some cognitive tasks even when they are single tasking.
Compared to LMMs, HMMs often exhibit poorer sustained attention, working memory, long-term memory, and impulse control.
In our lab, we found heavy media multitaskers performed worse on tests of working memory and long-term memory compared to light multitaskers.
This relationship held even when controlling for total media consumption.
Ongoing studies are assessing whether HMMs exhibit more frequent attention lapses during cognitively demanding tasks, measured via eye-tracking and EEG.
Fluctuations in pupil size and brain waves may relate to worse performance.
Does Media Multitasking Change How We Think?
An open and debated question is whether media multitasking causes differences in cognition and attention, or whether people with poorer attention tend to media multitask more frequently. Or both?
Longitudinal studies following individuals over time could help resolve this chicken-or-egg dilemma.
For now, evidence best supports a bidirectional relationship.
Heavy media multitasking early in life may reshape still-developing brain networks, priming them for inattention – while those prone to distraction may readily habituate to media multitasking.
Regardless of causation, media multitasking appears correlated with worse academic performance.
Students recall less from lectures and have poorer homework scores when concurrently texting, emailing, or using social media.
Practical Implications (Multitasking)
Multitasking has important implications for productivity, learning, workplace safety, and overall mental health.
The research highlights the wisdom of minimizing distractions to sustain focus, especially on tasks requiring working memory, impulse control, and comprehension.
While heavy multitaskers may thrive on switching between tasks, they may benefit cognitively from single-tasking.
Moreover, lighter multitaskers should be aware of multitasking’s costs and resist overloading themselves with competing goals.
For tasks that demand sustained attention like reading, writing reports, and driving, we should avoid attempting simultaneous activities.
Multitasking may breed a distractible brain unaccustomed to deep focus.
Of course, certain environments require multitasking, and individual abilities vary.
But knowledge of multitasking’s mental costs can lead to wiser choices about when to fully engage our minds versus divide our limited attention.
References
- Study: Multicosts of multitasking
- Authors: Kevin P Madore & Anthony D Wagner
