Very good point, Purex. I tell my ESL students that Americans like to talk a lot and are basically open and friendly; many Americans are touchy-feely and don't think twice about touching someone on the shoulder when they're conversing. The students often come from repressed cultures where it is unthinkable to directly meet someone's gaze, or talk to someone without first being introduced, etc., etc. I had the hardest time with a Vietnamese student who wouldn't open her mouth to practice the 'r' and l' sounds let alone try to physically show her where her tongue sor lips should be, when I suddenly remembered that it is considered impolite to show people the inside of your mouth in Vietnam!