This story in The Times Higher Education outlines how a professor at Lehigh University saw that his students who brought laptops didn’t do as well on tests as students who took notes the old-fashioned way. The story also digs into some neurological research that says the same thing.
Essentially, our brains seem to work a little like our ears do in this respect. If you are supposed to listen to a sound, you can do it much more easily when fewer other sounds are made around you, especially if those other sounds are more pleasant or more interesting than the one you are supposed to listen to. I, for example, would pay attention to the air conditioner if you told me that’s what I was supposed to do. But if, say, Angie Harmon began talking in the background, I would pretty quickly abandon the air conditioner for a sound that is of far more interest to me.
I can multitask, sort of, but not especially well. In fact, I have basically the same issue as does Microsoft Windows: if more than one task is running, one of them gets focus, and the others are shunted into the background until such time as I can manually intervene to bring them up. I tend not to listen to the A/C; in fact, given the nature of Oklahoma summers, I don’t notice it until it cycles off. There are times when this doesn’t happen for several hours, at which time I will be startled by the sudden reduction in background noise. I am reasonably certain, though, that if Angie Harmon were to happen onto my premises, she would have my undivided attention for the duration.