Multitasking and IQ: Why Task-Switching Costs So Much
Multitasking effectively lowers IQ by up to 10 points during the task. Here's how task-switching hits working memory, error rate and test performance.
Most people think they're good at multitasking. The research is clear that no one is – the brain switches between tasks, and every switch costs time, accuracy and cognitive capacity.
Multitasking is a myth
The prefrontal cortex holds one complex task at a time in working memory. What we call multitasking is really fast task-switching.
The switching cost
Each switch costs 0.5–2 seconds of re-orientation. On complex tasks, up to 40% of working time can go to switching. Error rate doubles.
Effect on IQ points
A King's College London study found multitasking (email + calls + text) temporarily cut measurable IQ by 10 points – more than a night of sleep loss. See also sleep and IQ.
How to train monotasking
Turn off notifications, work in 25–50 minute blocks with breaks, and batch email. Combine with mindfulness for durable focus.
Test yourself
Curious where you'd land? Take our free online IQ test – no sign-up required.
FAQ
- How much does multitasking lower IQ?
- A classic King's College London study showed multitasking (email + calls + text) temporarily lowered measurable IQ by 10 points – more than the effect of one night without sleep.
- Is multitasking real?
- Not really. The prefrontal cortex holds one complex task at a time. What we call multitasking is fast task-switching, and each switch costs 0.5–2 seconds of re-orientation.
- How do you train monotasking?
- Turn off notifications, work in 25–50 minute blocks with clear breaks, and batch email to fixed times. Combine with mindfulness for durable focus.