Crowding Into the Behavioral Sink Theoretical Propositions In 1962 John Calhoun conducted several experiments regarding his theories of crowding. Crowding, in his definition, was very different than population density though they sound the same. Calhoun begins by explaining that population density is several individuals in a given amount of space. Crowding, on the other hand, refers to the subjective psychological experience created by density. The article explains Calhoun's experiment and what the conclusion of that experiment then continued to other research regarding Calhoun's experiment. Calhoun's very first experiment started with a population of rats and an enclosed quarter-acre. With plenty of food, water, and bedding available, he observed these rats for 27 months. At the end of the 27 months, Calhoun ended his experiment with only 150 adult rats left. With the usual rate of reproduction for the rats in this ideal paradise, he expected to have 5,000 rats, not 150. Due to the stress of social interaction, reproductive and maternal behavior had been severely altered. The
population did not increase due to the high infant mortality rate within the enclosure. After observing these rats for 27 months and seeing the outcome, he became dedicated to finding out why this happened. The Method/Results Calhoun then conducted a series of three studies which consisted of either 32 or 56 rats placed into a 10-by-14-foot lab room divided into four pens. Each pen was connected with ramps for the rats to go in and out of. If you wanted to go from pen 1 to pen 4, the rat would need to go through both 2 and 3 to do so. Pens 1 and 4 had a master rat and organization while pens 2 and 3 became crowded with several distinct types of rats. This created what Calhoun called a Behavioral Sink. A behavioral sink is the outcome of any behavioral process that collects animals together in unusually great numbers. It acts to aggravate all forms of pathology that are in a group (p. 144). Some extreme pathological behaviors he observed were aggression, submissiveness, sexual deviance, and reproductive abnormalities.It was
observed that female rats lost their maternal abilities to move their young from danger and ended up abandoning their young where they died and eaten by other rats. Calhoun observed there to be an 80%- 96% mortality rate within the middle pens. By the end of the study, near half of the female rats died.
Significance of Findings Calhoun's findings were then used to compare other research on the effects of human-dense living, such as prisons. Within that research, they observed that in a crowded prison, there were more problems between the people there as non-crowded prisons appeared to have very little. Other research conducted with humans shows that crowding produces negative effects on peoples problemsolving abilities. Though other factors of the crowd showed different effects, crowding, regardless of the factors, produces a change in psychological behavior.