Are we designed to multitask?

If you think you've mastered the art of multitasking, think again. Your brain simply isn't optimized for split attention.

When you're distracted, it takes longer for your brain to get back on track. One study found that answering an email in the middle of a computer task put people an average of 20–25 minutes behind, even though the email itself only took 10 minutes. A third of the volunteers took more than two hours to get back on task, blaming "loss of context associated with the task switch" — the distraction took their minds somewhere else.

Practice won't make you a better multitasker, either. In a 2009 Stanford study, students deemed "heavy media multitaskers" were more easily distracted than those who didn't multitask as much, and struggled with focus, attention, and remembering information. Evidence shows that even young "digital natives" are suffering from the distractions of their chronic multitasking.

According to an NYU study, the part of the brain most responsible for focus is the thalamic reticular nucleus (TRN). It acts as a sort of switchboard for incoming sensory signals, and tells the decision-making region (the prefrontal cortex) which ones to pay attention to. It does that by suppressing the neurons for some senses and activating the neurons for others. But when it's overloaded, it makes mistakes.

That study found that mice exposed to several stimuli were significantly less successful in getting a food reward than those who just focused on one stimulus, even though the focus engines of the multitasking mice were firing on all cylinders. You may think you're fully focused on multiple things at once, but your performance is suffering.