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Behavioral sink


The ethologist John B. Calhoun coined the term "behavioral sink" to describe the collapse in behavior which resulted from overcrowding. Over a number of years, Calhoun conducted over-population experiments on Norway rats (in 1958–1962) and mice (in 1968–1972). Calhoun coined the term "behavioral sink" in his February 1, 1962 report in an article titled Population Density and Social Pathology in the Scientific American weekly newspaper on the rat experiment. Calhoun's work became used as an animal model of societal collapse, and his study has become a touchstone of urban sociology and psychology in general.

In the 1962 study, Calhoun described the behavior as follows:

The common source of these disturbances became most dramatically apparent in the populations of our first series of three experiments, in which we observed the development of what we called a behavioral sink. The animals would crowd together in greatest number in one of the four interconnecting pens in which the colony was maintained. As many as 60 of the 80 rats in each experimental population would assemble in one pen during periods of feeding. Individual rats would rarely eat except in the company of other rats. As a result extreme population densities developed in the pen adopted for eating, leaving the others with sparse populations.

[...] In the experiments in which the behavioral sink developed, infant mortality ran as high as 96 percent among the most disoriented groups in the population.

Calhoun would continue his experiments for many years, but the publication of the 1962 article put the concept in the public domain, where it took root in popular culture as an analogy for human behavior.

Calhoun retired from NIMH in 1984, but continued to work on his research results until his death on September 7, 1995.

Calhoun's early experiments with rats were carried out on farmland at Rockville, Maryland, starting in 1947.

While Calhoun was working at NIMH in 1954, he began numerous experiments with rats and mice. During his first tests, he placed around 32 to 56 rodents in a 10 x 14-foot case in a barn in Montgomery County. He separated the space into four rooms. Every room was specifically created to support a dozen matured brown Norwegian rats. Rats could maneuver between the rooms by using the ramps. Since Calhoun provided unlimited resources, such as water, food, and also protection from predators as well as from disease and weather, the rats were said to be in “rat utopia” or “mouse paradise,” another psychologist explained.


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