RAEBURN: So how do we define a multitasker? I don't know. We all know what a multitasker is in our own terms, but how do we define that a little more scientifically? How do you do it?

Dr. NASS: Well, we're talking about media multitaskers. So we're talking about people who are receiving and, you know, using multiple streams of information at once that are unrelated. So people, for example, chatting with a number of different people while working on a paper, while reading something, while listening to TV, while looking at the newspaper, etc.

RAEBURN: OK, and you have a way of sort of measuring that or defining it? Do you count the seconds somebody does something?

Dr. NASS: We're actually interested in chronic multitaskers. So what we do is we present people initially with a questionnaire that asks about different categories of media and says: How often, when you're doing this category of media, are you also using this category, also asking the amount of time. And then through various statistics, we're able to put together a profile of people who are either very, very frequently using many, many media and those who are eschewing media and using, at most, one or two at a time.

RAEBURN: And now, many of us in my business think of ourselves as great multitaskers, and we feel like we have to do it to get our work done - in many other businesses, too. And we think we're pretty good at it, a lot of us. What's going on here? This is frightening news.

Dr. NASS: Well, it is frightening. It was frightening to the researchers, too. One of the things that seems to be true is people who multitask very, very frequently believe they are excellent at it, and they're actually, as far as we can tell, the worst at it of any people.

RAEBURN: The people who think they're the best are the worst.

Dr. NASS: Correct, correct.

RAEBURN: What's going on? How can that be?

Dr. NASS: Well, we don't actually fully understand it. One possibility is that people who multitask frequently just like doing it. They like what is called exploring rather than exploiting. And because they're doing it all the time, they feel that they're good at it because it's hard to justify doing it all the time if they're not. That's one possibility.

Another possibility is there may be some other thing motivating the desire or belief that has nothing to do with their actual performance.

RAEBURN: Now, the - have computers made this a more common phenomenon than it used to be before? Did people always multitask or is it something new, as it seems to many of us to be?

Dr. NASS: They certainly didn't always multitask because it was frequently very hard to do so. One of the things the computer has done is to allow people to pull up many things at once on the screen, the notion of multiple windows enabling that. Of course, we also then have cell phones, which are now getting smarter and allowing us to do multiple applications on those. People frequently have multiple televisions in the home, so it's not just one location where they use television. Print medium, of course, are very mobile. So it turns out that the trend has been growing very, very rapidly and probably wasn't with us, you know, a long time ago, just because there wasn't access to that many media.

RAEBURN: Now, are you a multitasker yourself?

Dr. NASS: I'm actually dreadful at it.  I do do it sometimes, and it always impairs me.

RAEBURN: OK. Is that part of what prompted this study?

Dr. NASS: In a way. I was very curious because I live in a dormitory here at Stanford, and I was curious how these kids were doing so many things at once. And so I wondered, jeez, you know, what is their special gift? What is their remarkable talent that I seem to lack? And our research suggests they don't have one. In fact, they're worse at all aspects of multitasking.

RAEBURN: Your students are.

Dr. NASS: Yeah, well, all high multitaskers seem to be really bad at multitasking.

RAEBURN: Now, is there something they can do to get better at it? If they stop multitasking, will their cognitive abilities recover?

Dr. NASS: Well, there's definitely evidence that if they stop multitasking, they'll do better because of all the studies showing that multitasking impairs performance. We're not sure whether these abilities are built in the brain or whether in fact, practice makes them, in this case, not perfect, makes them worse at it. We just don't know that - that's one of the key areas. But there's no question whatsoever that multitasking, especially among those who do it the most, is at the very least ineffective and at the worst, harmful.

RAEBURN: Yeah, tell me a little bit more about the idea that it's harmful. It's one thing to be thinking you're good at it and not being very good at it, but the idea that it might actually harm your thinking ability is a little frightening.

Dr. NASS: It's very frightening to us, and I think the reason it's so frightening is we actually didn't study people while they were multitasking. We studied people who were chronic multitaskers, and even when we did not ask them to do anything close to the level of multitasking they were doing, their cognitive processes were impaired. So basically, they are worse at most of the kinds of thinking not only required for multitasking but what we generally think of as involving deep thought.

RAEBURN: Which is what?

Dr. NASS: So the three abilities we looked at were - the first is filtering: the ability to ignore irrelevant information and focus on relevant information. And I had thought, more than my other two colleagues, that that was a particular gift that high multitaskers had. But in fact, multitaskers are suckers for distraction and suckers for the irrelevant, and so the more irrelevant information they see, the more they're attracted to it.

The second ability is the ability to manage your working memory, keep it neatly organized, be able to - the way I usually think about it is, imagine having very neat filing cabinets where you carefully and quickly place things in the right cabinet, and when you need the information, you immediately know which filing cabinet to go to. They're actually much worse at that.

And finally, the biggest surprise to the two other authors of the study, Eyal Ophir and Anthony Wagner, the biggest surprise was that they're even slower and worse at switching from one task to another. You would've thought that, at the very least, would be the key gift of multitaskers, but they're actually worse.

RAEBURN: So they're really working against their innate abilities, to some extent.

Dr. NASS: Absolutely, and again, we don't know whether they're totally innate, whether they're innate plus learned, or learned. But one way or another, they're putting themselves in situations where at the very least, they're destined to do poorly, and at the worst, they are destined to permanently impair their cognitive processes.

Dr. NASS: No, that is exactly - and it's precisely a problem. Music, or at least instrumental music, seems to be the one modality that doesn't seem to lead to problems with multitasking. However, all the other ones you mentioned, certainly jumping from playing a game to browsing something to writing a Word document to email, that is definitely the type of activities we're thinking about that, in fact, are very difficult to do, particularly for high multitaskers.

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