Many people believe they are good at multitasking. Modern life often requires people to switch between several activities, such as answering messages while working, listening to music while studying, or driving while talking on the phone.
Because people often practice these combinations repeatedly, it can feel as if the brain is able to perform several tasks at the same time without difficulty. However, new research suggests that the human brain may not truly be able to handle two tasks at once, even after extensive practice.
A new study conducted by researchers from Martin Luther University Halle-Wittenberg, FernUniversität in Hagen, and the Medical School Hamburg has taken a closer look at how the brain handles multitasking.
The scientists wanted to understand whether people can truly perform two activities at the same time, or whether the brain simply switches very quickly between tasks.
Their findings suggest that even when people become very skilled through practice, the brain still has limits. The research was published in the scientific journal Quarterly Journal of Experimental Psychology.
In the study, researchers designed a set of experiments to test how well people could manage two tasks at the same time. Each task used a different sense so that they would not interfere with each other too obviously. Participants were shown a circle on a screen for a very short time.
Their job was to quickly judge the size of the circle and respond with their right hand. At the same moment, the participants also heard a sound through headphones and had to say whether the sound was high, medium, or low in pitch.
This meant that the volunteers had to use their eyes and their ears at the same time while responding with both speech and hand movements. The researchers carefully measured how quickly the participants responded and how many mistakes they made.
To see whether practice would improve multitasking ability, the participants repeated the tasks over several days. Some continued practicing for as long as twelve days.
As expected, practice improved performance. The more often participants completed the tasks, the faster they became and the fewer mistakes they made. Earlier studies with similar results had suggested that with enough practice, the brain might be able to remove what scientists call “dual-task costs.”
Dual-task costs refer to the loss of performance that happens when a person tries to do two tasks at once. In some past research, it seemed that this loss could almost disappear with enough training.
This idea led some researchers to believe that the brain might actually be capable of true parallel processing. In other words, the brain might be able to run two separate mental processes at the same time. This idea was sometimes described as “virtually perfect time sharing.” If true, it would suggest that people could train themselves to multitask almost perfectly.
However, the new study challenges this assumption. According to psychologist Professor Torsten Schubert from Martin Luther University Halle-Wittenberg, the results clearly show that the brain does not fully process two tasks in parallel.
Even after many days of practice, the brain still seems to rely on a very fast sequence of mental steps rather than true simultaneous processing.
The researchers also made another important discovery. When they introduced very small changes to the tasks, participants suddenly became slower and made more mistakes. These changes were minor, but they disrupted the routines that participants had learned during practice.
This shows that the brain’s ability to handle two tasks depends heavily on stable routines. Once those routines are slightly altered, performance drops again.
According to Professor Schubert, the brain is very good at organizing tasks in a sequence so that they interfere with each other as little as possible. Through practice, the brain learns to coordinate these steps efficiently.
However, this process has limits. When situations become more complicated or unpredictable, the brain’s cognitive system can quickly become overloaded and errors become more likely.
The findings are important not only for understanding how the brain works but also for improving safety in everyday life. Many daily activities involve some form of multitasking. For example, drivers often talk on the phone while driving, assuming they can handle both tasks at the same time.
However, the study suggests that even if people feel confident doing this, their brain is still dividing attention between tasks rather than processing them simultaneously.
Professor Tilo Strobach from the Medical School Hamburg explains that this research helps explain why multitasking can be risky in real-world situations. Jobs that require several actions at once, such as air traffic control or simultaneous translation, may place heavy demands on the brain’s processing system.
Even highly trained professionals may experience mental fatigue or increased error rates when tasks become too complex.
Professor Roman Liepelt from the FernUniversität in Hagen adds that understanding the limits of human information processing is essential for improving safety and productivity.
By recognizing these limits, researchers and designers can create better working environments, training systems, and technologies that support human attention rather than overload it.
The study highlights an important lesson about the human mind. Although practice can make people faster and more efficient at handling multiple tasks, the brain still operates within certain biological limits. Rather than performing two tasks truly at the same time, it rapidly switches between them.
These findings provide valuable insight into how attention and learning work. They also suggest that people should be cautious about relying too heavily on multitasking in situations that require high accuracy or safety. While humans are remarkably adaptable, the brain still functions best when attention can be focused on one task at a time.
If you care about mental health, please read studies about how dairy foods may influence depression risk, and 6 foods you can eat to improve mental health.
For more mental health information, please see recent studies about top foods to tame your stress, and Omega-3 fats may help reduce depression.
The research findings were published in the Quarterly Journal of Experimental Psychology.
Copyright © 2026 Knowridge Science Report. All rights reserved.
