ho can remember life before multitasking? These days we all do it: mothers, air-traffic controllers, ambidextrous athletes, high-flying executives who manage to eat, take conference calls, write e-mail and conduct board meetings all at the same time. We lionize those who appear to multitask effortlessly and despair at our own haphazard attempts to juggle even two tasks, secretly wondering if there exists a race of superior beings whose brains are hard-wired for multitasking feats. Only recently have neurologists begun to understand what our brains are up to when we do it. What they've learned offers hope to all multitasking delinquents out there.
1. Don't think you can actually do two things at once. Even when you think you're doing more than one thing simultaneously -- say, driving and talking on a cell phone -- you aren't. Unlike a computer, the brain isn't structured as a parallel processor. It performs actions, even very simple actions, in a strict linear sequence. You must complete the first task, or part of that task, before moving on to the next. What we call multitasking is actually task switching.
Hal Pashler, a professor of psychology at the University of California at San Diego, conducted an experiment in which he tested the brain's ability to respond to two different sounds in quick succession. What he found is that the brain stalls fractionally before responding to the second stimulus. The second sound is heard (the brain can take in information simultaneously), but it requires time, if only milliseconds, to organize a response. "When you really study precisely what people's brains are doing at any moment, there's less concurrent processing than you might think," Pashler explains. "The brain is more of a time-share operation." He adds, "When fractions of a second matter, we're better off not doing another task."
2. Prioritize. To know when to switch tasks, you must distinguish between the tasks you must perform and those you can afford to blow off.
Consider the experiment that Jordan Grafman developed at the National Institute of Neurological Disorders and Stroke (N.I.N.D.S.) in Bethesda, Md. It's a driving simulation in which you must avoid errant cars and jaywalkers, all while reciting sequences of numbers called out to you. Typically, your driving skills will grow more erratic as you pay attention to the numbers (although, frighteningly, you may not be aware of this). But when a virtual pedestrian dashes into the road, you'll most likely abandon the recitation. That's because in a driving simulation, avoiding killing people is the one challenge that outranks all others.
Before approaching multiple tasks, recommends Grafman, clearly establish which tasks are more important than others. "Mentally rehearsing," he says, "definitely improves performance."
3. Immerse yourself in your immediate task, but don't forget what remains to be done next. To switch tasks successfully, the brain must marshal the resources required to perform the new task while shutting off, or inhibiting, the demands of the previous one. At the same time, you must maintain the intention to break off at a certain point and switch to another activity. During such moments of mental juggling, a section of the brain called Brodmann's Area 10 comes alive. (Area 10 is located in the fronto-polar prefrontal cortex -- at the very front of the brain.)
The crucial role played by Area 10 in multitasking was documented in a 1999 study that Grafman helped conduct; the results were published in the journal Nature. Functional magnetic resonance imaging scans (functional M.R.I.'s) were given to subjects at the Institute of Neurological Disorders while they performed simple multitasking experiments. Blood flow to Area 10 increased when people kept a principal goal in mind while temporarily engaged in secondary tasks. "This is presumably the last part of the brain to evolve, the most mysterious and exciting part," Grafman says. "It's what makes us most human."
Paul Burgess, who researches multitasking at University College, London, has also been focusing on the role of Area 10. "If you're missing it due to injury or a birth defect," he explains, "you keep forgetting to do things." He points out that successful multitasking requires that you not continuously think about switching tasks. That is, the activation of Area 10 does not require constant, conscious rehearsing of the need to switch tasks. For instance, if you have to make an important phone call at the end of the day, you don't tend to make an explicit mental note of this fact every five minutes. Rather, you engage in a less explicit act of remembrance -- a kind of low-level arousal, Burgess speculates, in which blood flow increases to Area 10.
4. Depend on routines -- and compare new tasks with old ones. Multitasking becomes easier, scientists believe, when you make parts of the process routine. For example, driving, a familiar activity for many of us, becomes largely automatic -- the parts of the prefrontal cortex involved in cognition surrender to the regions deeper in the brain that govern visual and motor control. Once a task has been learned, the brain will try to shift the load for performance to its deeper structures, freeing up the cortex for other tasks requiring active cognition. That way, if something unexpected happens (like a pedestrian bolting into the road), you'll have the resources to deal with it.
When you are thrown into a new task, it's helpful to search for a comparison to something you've done before. The brain thrives on analogies. If you're suddenly forced to fly a crashing plane, you might want to draw on your PlayStation skills. "We solve task-switching dilemmas by trying to retrieve similar circumstances, similar situations being represented in similar regions of the prefrontal cortex," Grafman says. "If we don't, our experience will be totally chaotic, and we will clearly fail." He then laughs. "This cannot explain Art Tatum." The jazz pianist's wild two-handed improvising was pouring from his CD player when I entered his office. "With Tatum, nothing was routine. He must have had a great prefrontal cortex."
5. Make schedules, not to-do lists. And whatever you do, don't answer the phone. For those of us who find multitasking difficult, Burgess claims that the simplest aids -- like timers and alarms -- are the most effective. When the American astronaut Jerry Linenger was working aboard the space station Mir, he wore three or four watches with alarms set to notify him when to switch tasks.
"The alarm does not have to carry any information, just be a reminder that something has to be done," Burgess says. Studies have shown that neurologically impaired patients have been helped at multitasking by nothing more than someone clapping their hands at random intervals. An interruption breaks your train of thought and initiates a recall of what else needs to be done.
It's important, however, that the interruption itself not entail a task. For example, if the phone rings, don't answer it. Dealing with whatever the call is about will distract your brain from what you've already set out to do. Instead, use the interruption to see if you're on track with other activities. "Make calling others one of the things that needs to be scheduled," Burgess advises. "And if you have to answer the call, don't go straight back to what you were doing before the call arrived. Very deliberately check the time, and ask yourself if there was something else you should have been doing."
By following such an approach, you can actually change your brain. Visualizing the circumstances in which you need to switch tasks will establish a mental pathway that will be available when you really need it. As functional brain scans suggest, just by thinking about what we need to do and when we need to do it, we can increase blood flow to Area 10, our multitasking hot spot.
Age also improves us. Children are easily distracted from tasks by competing signals, and younger adults, with their maturing prefrontal cortexes, are best at learning and combining new tasks. As we age (and our brains atrophy), learning new tasks becomes harder, but we get better at extracting themes and prioritizing tasks.
"For tasks performed in a short period of time, the younger tend to do better," Burgess says. "Older people learn from their mistakes and begin to compensate over time. This is very encouraging science for those of us not 20 years old."
Catherine Bush is the author of the novel "The Rules of Engagement."