Ed Yong at Not Exactly Rocket Science covers a new study on media multitasking and its impact on cognitive control:

You might think that this influx of media would make the heaviest of users better at processing competing streams of information. But Eyal Ophir from Stanford University thinks otherwise. From a group of 262 students, Ophir indentified two sets of 'light' and 'heavy' multimedia multi-taskers from the extreme ends of the group. The heavy users were more likely to spend more time reading, watching TV, surfing the web, sending emails or text messages, listening to music and more, and more likely to do these at the same time.

The heavy group also fared worse at tasks designed to test their ability to filter out irrelevant information or, surprisingly, to switch from one task to another. In short, they show poorer "cognitive control", a loosely grouped set of abilities that include allocating attention and blocking out irrelevancy in the face of larger goals. They're more easily distracted by their many incoming streams of data, or less good at shining the spotlight of their attention on a single goal, even though they are similar to the light group in terms of general intelligence, performance on creativity tests, basic personality types, and proportion of women to men….

The key question here is whether heavy multimedia use is actually degrading the ability to focus, or whether people who are already easily distracted are more likely to drown themselves in media. "This is really the next big question," says Ophir. "Our study makes no causal claims; we have simply shown that media multitaskers are more distractable." The next step is to follow a group of people with different media habits over time to see how their mental abilities shift, and that's something that Ophir is working to set up.

Nonetheless, as ever-larger computer screens support more applications (Google Wave, anyone?), and social norms shift towards more immediate responses, it seems that multitasking is here to stay and perhaps merely in its infancy. It's important to understand if these technologies will shift our portfolio of mental skills, or equally if people who are naturally easy to distract will gravitate towards this new media environment, and encounter difficulties because of it.