Multi-tangle

But even off the road, the lure of multitasking - and our misconceptions about our ability to do it successfully - may be robbing us of time, efficiency, and the capacity to concentrate when we really need to.

At her job in a busy Boston public relations firm, 25-year-old Lillian Dunlap spends her days tending to the needs of clients. She fields emergency e-mails for one business while writing press releases for another and juggling phone calls from everyone. In today’s corporate culture and competitive job market, the person willing to take on the most gets ahead, she said.

“Every client has 10,000 things they need done, and with all the new technology, we’re expected to always be on call,’’ said Dunlap.

Researchers are discovering, however, that constantly switching tasks may be a lot less effective than it might appear.

“When you’re pushing yourself to perform two or more tasks, especially complicated tasks, it’s not beneficial. It’s extremely inefficient,’’ said David Meyer, a psychologist specializing in cognitive neuroscience at the University of Michigan.

In a 2001 study published in the Journal of Experimental Psychology: Human Perception and Performance, Meyer and his colleagues found that people who toggle between tasks lose valuable time in the transitions. The brain must refocus each time it switches activities, and the more complicated the task, the more time it takes to refocus. The time loss can be as little as tenths of a second per switch, but that can add up over the course of a day in which countless e-mails, texts, instant messages, face-to-face interactions, and any number of hands-on tasks involve such switches.

For the really hard stuff - writing important documents, expressing complex ideas, performing calculations - the time it takes for the brain to refocus stretches much longer, said Meyer.

“If you’re right in the middle of a paragraph and get interrupted, it could take hours to reconstruct what was in your mind and re-create the awareness you had before the interruption,’’ he said.

Laura Vanderberg, a biology researcher at Tufts University and assistant director of the Time Management Consulting Program at its academic resource center, said that one of her biggest challenges is getting students who are overwhelmed by multiple demands to understand the limitations of what’s known as working memory.

Long-term memory is nearly infinite and is able to simultaneously store the details of distant-past events such as a first kiss and a childhood broken leg. Working memory - the process of taking in and processing new information - is much more limited.

“It’s ‘mental counter space’ and there’s only so much of it,’’ said Vanderberg.

Almost everything we do takes cognitive, or conscious intellectual, energy, and thus takes up room on the mental counter. Things we do frequently, like brushing teeth or driving to work, may seem so routine that they are automatic, but in fact they tax the brain.

The very act of multitasking adds to the drain on the brain’s finite supply of real-time resources. Only a few things - breathing, heart rate regulation - can be done without pressuring working memory, said Vanderberg.

“If you can’t do it in your sleep, it is taking up cognitive energy,’’ she said.

For today’s children and young adults growing up in a multitasking world, surrounded by hands-free phones, portable personal computers, and enough Wi-Fi hotspots to stay linked in virtually anywhere, it might seem that young people would be more successful than older adults at multitasking, simply because they’ve had more practice.

In fact, the opposite may be true.

Researchers at Stanford University found that people who regularly juggle various electronic activities - like checking text messages while writing an e-mail and indulging in the latest episode of “Desperate Housewives’’ - actually had the highest deficit in skills that would make them good multitaskers, according to a study published in the August edition of the Proceedings of the National Academy of Sciences.

They couldn’t, for instance, block unimportant information or use short-term memory to switch between two tasks as well as their counterparts who chose to consume one media stream at a time.

Basically, they are distracted.

“They couldn’t help thinking about the tasks they weren’t doing,’’ said Eyal Ophir, one of the study researchers, who studies human-computer interactions at Stanford.

Recognizing when you are asking your brain to do too many important things at once is half the battle, said Vanderberg. “We see a lot of students are wired into multiple things at once, [and] they don’t even recognize it. It’s so omnipresent that you don’t realize it’s happening.’’

As technology advances, so, too, will the demand to multitask, predicted Todd Farchione, a clinical psychologist at Boston University.

“The more we rely on texting as a form of communications, the more we expect it to follow rules of verbal communication. You expect the person to respond if they are there, even when there are competing activities going on,’’ said Farchione. “When we get a text message, we feel like the person is talking to us. And in real conversations, there is rarely a 20-minute pause between questions.’’

And it’s not just friends who expect our electronic attention.

“As new media are made available to the public, what we’re left with is a doubling up and doing more and more things at once,’’ said Ophir. “It’s become a standard in the workplace to always be online, responsive to chat, and to always have your cellphone.’’

As Dunlap, the public relations worker, put it, “It’s becoming part of the culture.’’