From the moment we wake up to the moment we go to bed, we face a constant barrage of stimuli, all of which we’re expected to tackle. When we study, we play music to help us focus, and when we do homework, we try to get through multiple tasks at a time under the ruse that it’s more productive. We put on a show as background noise while we make notes and claim that completing simultaneous tasks is not just successful, but far better than going one by one. 

Saving a few scant minutes over completing a task with your whole undivided focus can have its drawbacks, however. Multitasking, as you’ve most likely heard by now, is a myth. Your attention span and task-focus is largely controlled by the prefrontal cortex, the part of the brain responsible for decision-making. Supporting it are two major sub-networks: the dorsal attention network, which directs focus in a deliberate, goal-oriented way, and the ventral attention network, which alerts you to unexpected events (like a phone buzzing). These networks can’t run two complex tasks at full capacity simultaneously; when they compete, performance on both tasks decline. 

Psychologists call this decline the “switch cost”. Every time your brain switches from one task to another, it has to reconfigure itself by disengaging from the task at hand, activating another, and dredging up relevant details from your memory to hold them close at hand. Studies using fMRI show that these transitions are associated with bursts of energy in the anterior cingulate cortex (a region in the frontal lobe that plays a role in cognitive processes), which reflects the extra effort required to switch gears. The result is evident in your work: slower reaction times, reduced energy, and faster mental fatigue. Over time, frequent multitasking has even been linked with reduced ability to filter distractions and impaired memory encoding. 

However, multitasking actually increases dopamine release in our brain–each time we switch tasks or get a new notification, we feel a small sense of accomplishment, reinforcing the behavior. In the short term, this creates an illusion of productivity; long-term, however, it trains the brain to seek novelty, undermining deep focus. 

The alternative is single-tasking. Focusing on one demanding activity at a time allows attention networks to coordinate more effectively, increasing accuracy and reducing fatigue or stress. Practical strategies like the Pomodoro method, mindfulness, and turning off push notifications have been shown to enhance sustained attention. Just like physical fitness, cognitive fitness improves with consistent practice, and cultivating focus can be one of the most powerful tools. In short, multitasking doesn’t expand your brain’s capability–rather, it constricts it.