Interesting article about doodling:
http://www.npr.org/templates/story/story.php?storyId=101727048

I am not sure if because I am a visual learner/artist (or maybe left handed) that I doodle for different reasons, but it is not out of boredom or to help me focus (I use note taking and to-do lists for that — which are very left brained activities). For me, doodling can spiral out of control and turn into an art project, so I really don’t doodle (because then I stop paying attention/participating and then turn into artist focusing on artwork). Doodling can be relaxing for me and I switch into very right brained activity — timeless, intuitive, and creative — not necessarily useful to stay on task or stay engaged. Still a very interesting article on doodling.