it may be my English heritage or my life as an introvert, but I really have issues with people getting really close to me. But I suppose most Americans are the same way. Of course, there are many among us who for whatever reason, did not read the American customs handbook section about personal space.
Harold Garfinkel's study of human behavior found out that are plenty of things that we can do to break social "rules" to get a reaction, most negative. He referred to these "Breaching Experiments"- Purposeful "violations" of social norms to study people's reactions (personal space experiments being the most popular). If you search, "personal space" or "breaching experiments" on You Tube, you will find a ton of them.
Using the your own personal experience with those who do not necessarily follow the "rules", your web research, the links that I have listed below, and any "experiment" you wish to conduct yourself, write a initial response looking into the topic of breaching and especially personal space issues. Why do some people feel extremely uncomfortable when someone "breaks the rules" and others seem to take it all in stride?