Multitasking also hits limits with practice, study finds - New study debunks the myth of perfect human multitasking

A new study has cast doubt on the idea that the human brain can multitask perfectly. Researchers from Martin Luther University Halle-Wittenberg and FernUniversität in Hagen found that, despite practice, true parallel processing remains impossible. Their findings challenge long-held beliefs about the brain's ability to handle multiple tasks at once without errors or delays.

The study focused on a phenomenon called Virtually Perfect Time Sharing, where people appear to perform two tasks simultaneously with little cost after extensive training. For years, this was seen as proof that the brain could process multiple tasks in parallel without limits. Prof. Dr. Torsten Schubert of MLU noted that earlier research often interpreted this as evidence of unlimited multitasking ability.

Participants in the experiment were asked to complete two tasks at the same time: judging the size of a briefly shown circle and identifying the pitch of a tone. With practice, they grew faster and made fewer mistakes. However, even small changes to the tasks caused delays and errors, revealing the brain's limitations. Rather than processing both tasks in parallel, the brain rearranges individual steps to reduce interference. This optimisation creates the illusion of multitasking, but the study confirms that true simultaneous processing does not occur. The researchers stressed that, no matter how much people train, the brain still switches between tasks rather than handling them at the exact same time.

The results have practical consequences, particularly in situations where multitasking is common. Activities like driving while using a phone or jobs requiring constant task-switching carry higher risks than previously assumed. The study shows that even with training, the brain's ability to juggle tasks remains fundamentally limited.