Computer scientist Dan Rockmore won’t allow them in his classroom:
When I created my “electronic etiquette policy” (as I call it in my syllabus), I was acting on a gut feeling based on personal experience. … Over time, a wealth of studies on students’ use of computers in the classroom has accumulated to support this intuition. Among the most famous is a landmark Cornell University study from 2003 called “The Laptop and the Lecture,” wherein half of a class was allowed unfettered access to their computers during a lecture while the other half was asked to keep their laptops closed. The experiment showed that, regardless of the kind or duration of the computer use, the disconnected students performed better on a post-lecture quiz. The message of the study aligns pretty well with the evidence that multitasking degrades task performance across the board.
According to this study, it’s precisely when laptops are used as one might hope – for note-taking – that they are a problem. Most people can type significantly faster than they can take notes by hand, and the natural tendency of most computer users is to take more notes – perhaps even to transcribe – at the expense of memory and comprehension. If you don’t have to think about what you are hearing and what is or is not worth writing down, you are not likely to listen as intently and actively.