One of the reasons for poor multitasking is poor decision making. People decide to multitask, or to switch tasks when it is not the best moment to do so. The mail/chat experiment I described earlier is an example of an experimental setup where people switch from one task to another at moments that they really should have sticked to the main task they were doing.
When people have to make decisions in ordinary tasks, they often base choices on utility. This means that they compare the potential payoffs for each of the choices, and pick the one with the maximum payoff. So when I want to go to the grocery store, and have to decide whether to walk, drive, or take the bicycle, the utility of these choices is based on how much time it takes, what my capacity to carry groceries will be, and how much money it costs. Taking all these factors into account is quite complex, so many theories assume we base our utility estimations on past experiences instead of trying to calculate the consequences of future action.
The problem in multitasking is that we cannot use the same strategy as in normal decision making. In multitasking, each of the individual tasks has its own utility, and from the perspective of that calculation it is always a bad idea to multitask. If we were perfect utility maximizers, we would never multitask, which is obviously not true.
So, what is the basis for our decisions? A possible explanation for which we have collected some evidence (including the mail/chat experiment) is what I call resource availability. If there is another tempting task, and we have mental resources available to do that task, we go and do that task, either by adding it to what we are already doing, or by switching to it. By mental resources I mean memory, visual attention, working memory, motor control, etc. Let me give some examples.
|A wedding in China: obviously the groom was too boring....|
Many real-life situations are in traffic, whether in a car, or walking, or cycling. I like to listen to music or podcasts while running to keep all my mental resources happy. Dutch students on a bicycle seem to have an incessant need to call their friends when they are on a bicycle. Whenever I am stuck writing the next sentence of this Blog, email and Facebook are tempting me.
In the end, our poor decisions in multitasking may be a consequence of our continuous attempts to escape boredom. Boredom forces us to jump from one attractive electronic carrot to another, but this never completely satisfies us.