Scientists have long asserted that the human brain is not designed for multitasking, but a new study is challenging that understanding. Researchers previously explained that when we believe we are multitasking, we are actually rapidly switching between tasks. This is because the prefrontal cortex, the brain region responsible for thinking, can only handle one thing at a time. However, new research reveals that another brain region involved in memory can assist over time.
The Study's Findings
When participants performed image-sorting tests over several weeks, the tests initially activated the prefrontal cortex and later activated the temporal cortex. Over time, the brain is remodeled, according to Maximilian Riesenhuber, a professor of neuroscience at Georgetown University School of Medicine. The prefrontal cortex passes responsibility to the temporal cortex, freeing itself for other tasks and increasing capacity.
“What we show is that the circuitry actually changes so the brain can do two things at once,” Riesenhuber said. “This really is true multitasking.”
Understanding the Process
The researchers aimed to understand why people need to focus when learning a new task but can do other things simultaneously once experienced. For example, long-time drivers can listen to music and engage in conversations while driving.
In the small study, men and women were trained to sort morphed images of cars into two categories using an image-sorting app, completing over 30,000 trials over 5-10 weeks. Brain scans before and after the trials revealed the change.
“Previous studies have shown that parts of the temporal cortex can be activated by particular object categories in experienced observers – birds, cars, even Pokémon – but a limitation of all of those studies is that they only looked after people became experts. The strength of this study is that it is longitudinal: we measure before and after training, so we can see that extensive training essentially put a category-selective area in the temporal lobe that was not there before,” said Patrick Cox, an assistant professor of psychology at Lehigh University.
Individual Differences
Interestingly, some people were found to have brains better suited for multitasking than others, Riesenhuber told NBC News. The reason remains unclear. However, multitasking has been linked to stress and other mental health impacts, as noted by Brown University Health, which is why experts say it could hinder productivity.
“This is unlocking a whole new set of questions,” Riesenhuber said. “What is the source of that variability? We don’t know yet.”
Implications and Future Research
The findings have implications for understanding compulsive behaviors and help explain why humans are adept at continuous learning, a capability that artificial intelligence still struggles with. The research could be applied to better train generative AI.
The next step for scientists is to study the underlying process of how learning moves from one brain region to another and to determine the limits of multitasking as observed.
“Another really interesting question is what kinds of tasks can be learned well enough to do in parallel,” said Cox. “We can walk and chew gum at the same time, but looking at our phones to text while driving will never be safe, because we take our eyes away from the road. It comes down to being able to train fully separate neural circuits for two tasks to become compatible.”
