Don't try to learn.
"Results are always worse when you multitask, but in some areas they're especially compromised," says Russell Poldrack, PhD, associate professor of psychology at UCLA. Learning takes a big hit, for instance. "Our research shows that if you try to master something while splitting your attention, brain activity switches regions—from memory building to short-term habit making," he says.
A good rule of thumb is to multitask what you want to execute, rather than absorb, and choose jobs where mistakes won't matter.
It may seem counterintuitive, but similarities make multitasking harder, according to Poldrack. Before getting to the bottleneck, mental processes often originate in different parts of the brain. Pick two from the same area and they can become garbled. For example, you may enjoy reading with music on, but if you time yourself, you'll likely turn the pages much faster when there are no lyrics to distract you from the text.
Try to match projects with different modalities—like reviewing a report while on the stationary bike.
Israeli Air Force cadets trained to pay attention to specific aspects of a video game performed better in actual flight than others who just played the game, one study showed. "Focusing on each task's relative importance allows you to allocate your resources for maximum efficiency," says Poldrack.
Tech-dexterous teenagers are probably no better wired to ace computer games than the rest of us; they've just spent more time practicing with their gadgets, says Marois. Researchers believe that if you repeat a set of skills over and over in exactly the same order and way, you will get noticeably better.
Try to make at least one task something you do all the time. This allows you to fit the others into an already established pattern.