Biology in the News Explained

Multitasking is a Myth

Neurophilosophy recently posted on current research on why our brains have trouble paying attention to several stimuli presented in quick succession. While getting at the mechanisms behind these processing “bottlenecks” is an ongoing endeavor, it has actually been known for some time that what some people proudly describe as their ability to “multitask” is actually no such thing. Humans (and probably other animals as well?) are actually terrible at this, and the conceit that we are good at it is actually responsible for loss of productivity. So it’s not exactly clear why an article trumpeting this as news has appeared in the popular media. Nevertheless, the article motivated me to read up a bit more on the topic. I focused on the recent paper: Sigman, M. and Dehaene, S. 2006. Dynamics of the central bottleneck: Dual-task and task uncertainty. Plos Biology 4:1227-1238.

The authors make a few relevant observations. Referencing what has been previously known:

A dynamic trace of central limitation is … manifested at a slower time-scale (seconds to minutes) in the inability to rapidly switch the control processes that harness together independent processing modules … This effect is most evident in task-switching paradigms, which show, using a variety of different experimental manipulations, that reaction times increase when participants change between different task configurations…

Typical result – multitasking slows us down. But why? Here is one of the authors’ conclusions:

Although central processing of task 2 can be executed immediately after central processing of task 1 has been completed, the outcome of task 2 cannot be executed until the system has disengaged from the previous response-setting mode.

This means that in addition to the lag in performing a second task, due to the need to finish the previous task first, there is an added lag during which our brain has to shift gears from the first task to the next. So if you add up all the time one task takes if you focused on it completely to the time the second task takes if you focus on it, it will be less than the time you take doing them both together. Thus, as the example in the Times article suggests, shifting your attention back and forth from the road to your cell phone introduces dangerous delays in your driving response time. This probably explains why the accident rate for cell phone users is said to be equivalent to that of drunk drivers, who also suffer from impaired response time.

But what do a few seconds here and there matter for a situation in which we are not in control of a lethal weapon hurtling 75 mph down the highway? The problems go beyond time delays; there are impacts long term memory as well. For those of us in education, the problems introduced by task-switching too often are obvious. The standard university schedule of four to six classes every day, mostly lectures, pretty much could not be a worse way for students to learn. Many professors may not like this characterization; obviously we went through this system and did well enough to become professors ourselves. The problem is, the great majority of our students are not like us. They are not riveted to a lecturer’s every word because they find the topic so fascinating, thinking about it in depth after class. No, most of our students attend our lectures, do their best to listen, and probably most of them genuinely understand the material at the time it is presented. When they do lousy on our tests, however, we blame their inability to apply themselves, and certainly that is a factor. Unfortunately, our system is setting up all but the brightest and hardest-working students to fail, when it comes to long term retention of the material in a class. Even many students that manage a B or C in a prerequesite might as well have not taken it when they get to the next class in the sequence.

It is known that humans possess both short-term and long-term memory. For memories to be shifted from the short-term to long-term, these memories must be retuned to and further processed. But when a student leaves my lecture and heads for the next class, what happens? Simply, the toilet flushes – all that new information sitting there in short-term memory waiting to be processed gets dumped instead, as the new information takes over. The student does not think about the material usually for two more days until the next lecture, which then is harder to follow because the student has not processed properly the previous information which is critical to the understanding of subsequent material. Even worse, the student usually does not review his or her notes until the night before a test, when they no longer make sense because the broader ideas associated with those notes have not been properly processed and stored in long-term memory. Our system is idiotic and stupid.

But there is indeed a better way, that a few colleges in the U.S. (at least) employ: block scheduling, or the taking of one class at a time. In this model, the students take one class for three hours of class time every day for 18 days, which represents the class hours necessary for a 4-credit class. Actually, many people are familiar with this format from taking summer session classes. Summer session students, though, may not have received the same benefit because for students to be able focus on the material, you can’t lecture at them for 3 hours – meaning you can’t take a semester class and force it into the block format as is if you want to see a real change in what the students retain from the course. Fortunately, the block format is perfect for lab exercises, field experiments, or other hands-on tasks that also do a much better job of relating concepts than the passive absorption of information spoken by a lecturer, so the students get two better ways of learning for the price of one. But more important, for three and a half weeks, students are thinking about the material in only one class, not half-listening to (or skipping) a lecture while they worry about an exam next period. They have the time to follow the connections in the material, to internalize the relevant ideas which make the material make sense, simply to think about it, not just mindlessly write down notes that they don’t look at again for weeks. They come to class, because they learn quickly that to miss a day is to miss a week on the standard schedule, and miss with it a vital component of the class. They become comfortable with the terminology associated with the field of study, which in my experience rarely happens in the semester format.

So why don’t more schools do this? Number one, there would basically be no point with a class of 300 students because you would be reduced to the lecture format anyway, and standard lectures are 50 minutes because that’s about all our attention spans can handle as it is. Number two, this is more work for the faculty, because teaching in this environment is highly interactive when done properly. It is also much more intense to grade tests, papers, etc. in a compressed format quickly enough that students benefit from your feedback. But at a small college, it can be done when the faculty care about their students’ performance.

Our big university model is basically there because it’s the cheap, easy way to chunk students through and give them the degrees they have paid for. But I think most of us teaching at colleges and universities lament the lack of true liberal arts education that students are receiving there. Simply, most of our graduates are not critical thinkers. Were they ever? That is probably debatable, but many more people go to college now than used to, and a degree probably provided some basic measure of assessing the competence of, say, a potential employee. It’s not clear to me that it does at this time.

Colleges now on the block program full time are Colorado College, Cornell College, Tusculum College, and the University of Montana Western.


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