In a world where population is getting larger and larger, space seems to be getting smaller and smaller.  But while wide open fields are now becoming a rarity and crowded areas are more of the norm, personal space remains to be one thing that people guard closely.  But how big is personal space?

According to an article written by Richard Grey, the Science Correspondent of The Telegraph, it's from eight to 16 inches from the face.  This is based on a research conducted by the Department of Neuroscience at the University College London; and is more about a person's defensive peri-personal space rather than social personal space.

Dr. Gian Domenico Iannetti, one of the researchers, said, "This space is very much related to defense - the point where we start to feel threatened. It is linked to social personal space but it is not the same."

This personal space, he said, tends to change depending on the context or situation.  It becomes bigger when a person is anxious or when a place is perceived as dangerous.  Learning more about this could help authorities such as the police, medical personnel, or emergency response teams in assessing threats or other stressful situations.

According to the study, this defensive peri-personal space is not gradual but is rather abrupt, like an invisible barrier.  It is a defensive mechanism inherent in the brain, and invading personal space of another makes that person feel threatened.

"In places like the tube (British term for underground railway), it is not a threatening situation, so we are probably more accepting of being that close to people. It can be annoying but not threatening," Dr. Iannetti explained.

In a more social context, Debbie Mayne of About.com says, "Think of your personal space as the air between your body and an invisible shield, or bubble, you have formed around yourself for any relationship." 

She adds, "Average comfort levels of personal space distance in the U.S... (is) Approximately 3 feet to 10 feet for casual acquaintances and co-workers (and) More than 4 feet for strangers."

The etiquette expert also says that culture and country is a determining factor on what is comfortable in terms of personal space. 

The Telegraph states, "Dr Iannetti said he hoped to carry out research on subjects from other countries to better understand differences between cultures."