Perhaps unsurprisingly, it turns out that multitasking is not efficient. Slow Down, Multitaskers; Don’t Read in Traffic, from Sunday's New York Times quotes several recent & forthcoming studies detailing the inefficiencies of multitasking.
Some interesting tidbits:
"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 René Marois, a neuroscientist and director of the Human Information Processing Laboratory at Vanderbilt University." (emphasis mine).
Marois' article was in the November, 2006 issue of Neuron:
"When humans attempt to perform two tasks at once, execution of the first task usually leads to postponement of the second one. This task delay is thought to result from a bottleneck occurring at a central, amodal stage of information processing that precludes two response selection or decision-making operations from being concurrently executed. Using time-resolved functional magnetic resonance imaging (fMRI), here we present a neural basis for such dual-task limitations, e.g. the inability of the posterior lateral prefrontal cortex, and possibly the superior medial frontal cortex, to process two decision-making operations at once. These results suggest that a neural network of frontal lobe areas acts as a central bottleneck of information processing that severely limits our ability to multitask."
Further, the Times article continues, the perception that young'uns are better able to multi-task than oldsters is incorrect: Researchers at Oxford's Institute for the Future of the Mind "... suggests the popular perception is open to question. A group of 18- to 21-year-olds and a group of 35- to 39-year-olds were given 90 seconds to translate images into numbers, using a simple code. ... The younger group did 10 percent better when not interrupted. But when both groups were interrupted by a phone call, a cellphone short-text message or an instant message, the older group matched the younger group in speed and accuracy."
Hmmm. Guess I really should curb my simultaneous music-tweaking, email-checking, beverage-slurping, and (work OR driving).
Slow Down, Multitaskers; Don’t Read in Traffic
By STEVE LOHR, New York Times, 3/25/07
"Think you can juggle phone calls, e-mail, instant messages and computer work? New research shows the limits of multitasking."
Isolation of a Central Bottleneck of Information Processing with Time-Resolved fMRI
Paul E. Dux, Jason Ivanoff, Christopher L. Asplund, and René Marois
Neuron 2006 52: 1109-1120