A lot of the Ars readership would probably fit this description: TV on in the background, computer screen in front of them, and various windows—mail, chat, browser—vying for attention. Although most people find themselves multitasking, we're actually remarkably bad at it. Humans actually switch attention rapidly rather than truly multitasking, and tend to lose whatever is in our working memory when doing so. Nevertheless, a number of people tend to attempt to process multiple streams of information at once, which has prompted researchers to ask whether these individuals are especially good at juggling simultaneous inputs.
The answer, according to a paper that will appear in the Proceedings of the National Academies of Science later this week, is that they may actually be worse; heavy multitaskers tended to be more readily distracted by extraneous information than their more focused peers. That doesn't mean that multitasking is a total loss, as there may be benefits that weren't tested in this study, but it does make the case that heavy multitaskers might want to consider the limits of their habits.