Multitasking, many people say, is on the rise. Multitasking is doing two or more things at once. If you watch the news, you can see evidence. Bus drivers sending text messages, and the nearly universal practice of having conversations on the telephone while driving.
A recent study shows that people who habitually multitask actually are worse at switching back and forth between mental tasks than people who don’t. A study reported this week in the Proceedings of the National Academy of Sciences (early edition; August 23, 2009) shows that multitaskers have trouble screening out irrelevant information while performing several tasks. Eyal Ophir and his colleagues at Stanford University used several cognitive tasks including the same n-back task used to in other studies to train working memory.
People who reported the highest use of several media simultaneously (e.g., watching television, surfing the Web, and texting) were more likely to be distracted and performed more poorly on the n-back task.
So what do we make of earlier studies that show that n-back training may improve working memory, fluid intelligence, and even change brain receptors? This may be a case of comparing things that are superficially similar but basically different. Habitual multitasking may lead people to perform more poorly on a variety of tasks, most notably, driving. This habitual multitasking should be distinguished from the working memory training in which the n-back task is used. Working memory training can improve performance, but it may be that constant multitasking does not.