Think you’re great at multitasking? Answering texts, listening to a podcast and finishing work at the same time?

Your brain may disagree.

A new study out of Germany suggests that people can’t truly do two tasks at once, even after lots of practice. Instead, the brain quickly switches between tasks, which can still slow performance and increase mistakes.

The research, conducted by scientists from Martin Luther University Halle-Wittenberg, University of Hagen and Medical School Hamburg, was published recently in the Quarterly Journal of Experimental Psychology.

In the study, volunteers were asked to complete two tasks at the same time. 

They had to use their right hand to report the size of a circle shown briefly on a screen while also saying whether a sound played at the same time was high, medium or low.

Researchers measured how quickly participants responded and how many errors they made. The test was repeated for up to 12 days.

With practice, people became faster and made fewer mistakes. Earlier research suggested that training might allow the brain to handle two tasks at once, otherwise known as "dual-tasking."

But the new study found that’s not really happening.

"This phenomenon, known as virtually perfect time sharing, has long been considered evidence of true parallel processing in the brain and proof that our brain is capable of unlimited multitasking. The results of our study clearly contradict this assumption," said lead author Torsten Schubert, a psychologist at Martin Luther University Halle-Wittenberg.

Researchers also found that even small changes in the tasks made people slower and more likely to make mistakes.

“Our brain is very adept at sequencing processes so that they no longer interfere with each other; however, this optimization has its limits,” Schubert explained. 

"In particularly challenging situations, our cognitive apparatus therefore tires very quickly and becomes error prone," he added.

What's more, "our results show why multitasking can often be risky in everyday life, despite routine, for example when driving and talking on the phone at the same time," Tilo Strobach, a professor at the Medical School Hamburg, added.

The research could also help improve safety in jobs that require handling several tasks at once, such as air traffic control or translation.

“Our study sheds new light on the limits of human information processing,” said University of Hagen psychology professor Roman Liepelt.

"Understanding such cognitive bottlenecks is crucial for improving work processes, learning environments and safety measures in everyday life," Liepelt said.