The online BMJ Dec 13 published a fascinating French study that Raffi Consunji brought to my attention. It suggests that drivers whose minds wander may be responsible for as many as half of all car crashes. The study was aiming to identify dangerous driving distractions in order to develop technologies that can alert drivers. When you stop to think about it (no pun intended) taking your mind off the road may lead to more driving errors. This is more likely to occur among those with attention deficit hyperactivity disorder (ADHD) or who take certain medications. In 52 percent of the 1000 people interviewed following a crash, the “drivers said their minds wandered somewhat just before the crash. Thirteen percent said their thoughts were highly disrupting or distracting”.

http://www.nlm.nih.gov/medlineplus/news/fullstory_132224.html