Why is it so uncomfortable to stand really close to a stranger? Sure, there are the potentially icky things. Sometimes an elevator car is so crowded that you can smell a fellow rider's shampoo or chewing gum (or worse). But even when a stranger is perfectly groomed, it's usually a bit revolting to be pressed against him in public. Why?
A team of scientists from Caltech put SM through a series of tests in which they asked her to indicate the position at which she became uncomfortable as another woman, a researcher, approached her. SM's preferred personal distance was 1.1 ft. (0.34 m), about half the preferred distance (2 ft., or 0.64 m) of a group of comparison subjects. At 1 ft., you can easily discern whether someone showered after the gym — although in the lab experiment, the Caltech researchers made sure the experimenter was well-scrubbed and had just chewed gum before interacting with SM.
From the Upcoming ueue, submitted by Rossy21.
Just add the Benny Hill music...
... a person from India attempting to talk to someone from Britain can often cause situations where one person steps forward to enter what they perceive as a conversational distance, and the person they are talking can step back to restore their personal space.