Personal space and territory

Having an area of personal territory in a public space, e.g., at the office, is a key feature of many architectural designs. Having such a 'defensible space' can reduce the negative effects of crowding in urban environments. The term, coined by John B. Calhoun in 1947, is the result of multiple environmental experiments conducted on rats. Originally beginning as an experiment to measure how many rats could be accommodated in a given space, it expanded into determining how rats, given the proper food, shelter and bedding would behave under a confined environment.
Under these circumstances, the males became aggressive, some exclusively homosexual. Others became pansexual and hypersexual, seeking every chance to mount any rat they encountered. As a result, mating behaviors were upset with an increase in infant mortalities. With parents failing to provide proper nests, thoughtlessly ditching their young and even attacking them, infant mortality rose as high as 96% in certain sections. Calhoun published the results as "Population Density and Social Pathology" in a 1962 edition of Scientific American.
Creating barriers and customizing the space are ways of creating personal space, e.g., using pictures of one's family in an office setting. This increases cognitive control as one sees oneself as having control over the competitors to the personal space and therefore able to control the level of density and crowding in the space.