During a discussion with a friend who is a professor at a medical college in Wisconsin, I mentioned the fact that it is accepted behavior amoung the students to use their electronic devices during my lectures, and asked for his opinion on the subject. He stated that the problem has become quite epidemic to the point that his college has gone to the extreme by using paint on the walls of the lecture hall which is RF proof, that is, no signals in or out. I find it quite unnerving that even though I stipulate on the first day of class that the use of cellular devices is strictly forbidden during my lectures,and that if a cellular device is viewed during an exam, an automatic zero on that exam has been achieved, students find it necessary to blatently disobey the mandate. It has become a Pavlovian reflex to bring a phone out at any given time! I have heard excuses, which border on the absurd such as "I am unable to read an analog clock, and was merely checking the time". Has anyone, aside from RF "proofing" the room had any luck in stopping this behavior? Thanks in advance for your responses.