Does multitasking make you less productive?

These experts have some basic advice. Check e-mail messages once an hour, at most. Listening to soothing background music while studying may improve concentration. But other distractions--most songs with lyrics, instant messaging, television shows--hamper performance. Driving while talking on a cell phone, even with a hands-free headset, is a bad idea.

In short, the answer appears to lie in managing the technology, instead of merely yielding to its incessant tug.

"Multitasking is going to slow you down, increasing the chances of mistakes," said David Meyer, a cognitive scientist and director of the Brain, Cognition and Action Laboratory at the University of Michigan. "Disruptions and interruptions are a bad deal from the standpoint of our ability to process information."

The human brain, with its hundred billion neurons and hundreds of trillions of synaptic connections, is a cognitive powerhouse in many ways. "But a core limitation is an inability to concentrate on two things at once," said Rene Marois, a neuroscientist and director of the Human Information Processing Laboratory at Vanderbilt University.

Marois and three other Vanderbilt researchers reported in an article last December in the journal Neuron that they used magnetic resonance imaging to pinpoint the bottleneck in the brain and to measure how much efficiency is lost when trying to handle two tasks at once.