Multitasking also hits limits with practice, study finds - Study reveals the brain cannot truly multitask—even with practice

A new study has found that the human brain cannot truly multitask, even with extensive practice. Researchers tested whether people could perform two tasks at once—but the results showed the brain still works on one task at a time. The findings challenge the idea that humans can handle multiple actions simultaneously without trade-offs.

Scientists from Martin-Luther-Universität Halle-Wittenberg, FernUniversität in Hagen, and Hamburg Medical School ran an experiment to test the brain's limits. Participants completed two tasks repeatedly over 12 days: judging the size of a circle and identifying the pitch of a tone. With practice, they got faster and made fewer mistakes.

However, when small changes were introduced to the tasks, errors increased and response times slowed. This revealed that the brain does not process tasks in parallel but instead optimises the order of steps to reduce interference. Even after training, the brain still switched between tasks rather than handling them at the same time. The study highlights risks in situations where multitasking is assumed to be possible. For example, driving or jobs requiring constant task-switching may suffer from slower reactions and more mistakes, as the brain cannot truly focus on two things at once.

The research confirms that the brain works sequentially, not in parallel, even after training. While practice improves speed and accuracy, the brain still processes tasks one after another. These findings suggest that relying on multitasking in critical situations could lead to errors and delays.