The term proxemics was introduced by anthropologist Edward T. Hall in 1966 to describe set measurable distances between people as they interact. The effects of proxemics, according to Hall, can be summarized by the following loose rule:
Hall's human distance-spacing theories were largely based on the early animal-spacing studies in Zoosemiotics of German zoologist Heini Hediger, as found in his 1955 book Studies of the Psychology and Behavior of Captive Animals in Zoos and Circuses. Hediger, in animals, had distinguished between flight distance (run boundary), critical distance (attack boundary), personal distance (distance separating members of non-contact species, as a pair of swans), and social distance (intraspecies communication distance). Hall reasoned that, with very few exceptions, flight distance and critical distance have been eliminated in human reactions, and thus interviewed hundreds of people to determine modified criteria for human interactions.