So...there's this guy at work who gets right in my face when he talks. He stands about 10 inches away and looks right at me while he talks. He makes me very uncomfortable, and I find myself backing away from him. My neighbors constantly look over the fence into my yard, and sing out a cheery Hello whenever I go outside. It bugs me and I feel invaded. What's going on? How come this guy feels the need to talk so close, and how come my neighbors don't respect my need for privacy?

There's this concept known as personal space. Personal space is defined by behavioral psychologists as "an area around a person’s body into which others may not come. Very significant aspect of human social interaction. Can lead to behaviors as extreme as avoidance and aggression. I find this idea totally fascinating, so I did some studying on it.

Personal space has been described as a "bubble" surrounding each person. The size of the bubble varies widely from person to person, culture to culture and situation to situation. Because Mediterranean and Asian countries are more densely populated, their personal space zones are much closer to the body than those of Americans and Northern Europeans. Americans, in general, require 6 to 8 square feet per person. Each individual develops their own comfort zone based on experience, surroundings, and even gender. Women, in general, have a smaller space requirement. An example of this can be seen in movie theatres where two women attending a movie together will usually sit next to each other, while two men will often leave a seat between them. The shape of the area also varies between genders. A study done in 1975 at Georgetown University showed clearly that women tend to protect space next to them, while men tend to defend the space directly in front of them. The idea for this study was discovered by watching how males and females arranged their books and packs on library tables when studying.

When personal space is violated, as is often necessary in urban situations such as mass transit, waiting in lines, and close working quarters, people adopt coping mechanisms. The person holding a newspaper up on the bus is probably establishing a boundary. People in large cities tend to not look each other in the eye, maintaining at least that little bit of privacy. Office furniture is often arranged to enclose a small area that "belongs" to the person working there. People on an elevator will slightly shift their stance to face a different direction than the people around them.

When a person enters another's personal space, there are definite physical symptoms. "The violation of personal space increases tension levels enormously," says Robert Sommer, a psychologist at the University of California-Davis and author of the book "Personal Space." Sommer conducted research by going to parks and libraries and deliberately violating the personal space of innocent bystanders to see how they reacted. When people's space is trespassed upon, he says, "It provokes cathartic responses. They begin tapping their toes, they pull at their hair, they get completely rigid. It may not trigger a full-blown schizophrenic episode, but it's clearly not good for your health." Police investigators are taught to invade a suspect's personal space during questioning to gain a psychological advantage. "This is the way animal trainers tame lions," Sommer says. "By moving forward, moving back, constantly pushing the limits."

There's even a name for the study of personal space. In the 1960s, American anthropologist Edward T. Hall pioneered the field that came to be known as proxemics -- the study of humans' behavioral use of space. Hall said that personal space can be viewed as an extension of the human body, and he defined four distinct zones: the intimate zone, for whispering and embracing (within 18 inches of your body); the personal zone, for conversing with close friends (18 inches to 4 feet); the social zone, for conversing with acquaintances (4 to 10 feet); and the public zone, for interacting with strangers (10 to 25 feet). You can visualize these zones as the expanding concentric sectors on a dartboard, with your body as the bull's-eye.

Reflecting on what I've learned I understand the guy I work with, and my response to him a bit better. He grew up in a city in a family with 5 kids. I grew up on a huge ranch with only a single brother. His concept of personal space was developed in a crowded apartment surrounded by a teeming city. Mine was developed in a large ranch house surrounded by acres of pastures. My neighbors, who I consider to be invading my privacy, didn't grow up on a remote ranch like I did, and probably have more typical suburban attitudes about appropriate social interaction between neighbors. It still bugs me though.