Rat Park was a 200-square-foot (18.6 m2) housing colony built for a group of white Wistar laboratory rats in 1981 by American psychologist Bruce K. Alexander at Simon Fraser University in British Columbia, Canada.
The colony was built to examine Alexander's hypothesis that drug addiction is a myth and that continued drug use, particularly the use of heroin, is largely the product of unhappiness, not neurophysiological compulsion. Alexander hypothesized that the addiction to morphine commonly observed in laboratory rats exposed to it is attributable to the conditions in which they are normally kept, and not to any addictive property of the drug itself. Laboratory rats are "gregarious, curious and active creatures," Alexander told the Canadian Senate in 2001, but are isolated in cramped metal cages, then "subjected to surgical implantations in the hands of an eager (but seldom skillful) graduate student, followed by being tethered in a self-injection apparatus." Such experiments show only that "severely distressed animals, like severely distressed people, will relieve their distress pharmacologically if they can," he said. 
Better surroundings, Alexander believed, would reduce or eliminate the apparent dependence. To test his hypothesis, he built Rat Park. It was 200 times the square footage of a standard laboratory cage. There was companionship, with 16–20 rats of both sexes in residence, an abundance of food, empty tins for burrowing, balls and wheels for play, a special space for mating, shavings for nesting, and a private place for giving birth (Slater 2004). The results of the experiment appeared to support Alexander's hypothesis. The control group housed in the usual laboratory conditions consumed up to 20 times more morphine than the rats in Rat Park, and even those already addicted weaned themselves off the drug once moved there. They wanted to play, eat, and mate, Alexander concluded, not be anesthetized. "Nothing that we tried," he wrote, "instilled a strong appetite for morphine or produced anything that looked like addiction in rats that were housed in a reasonably normal environment." 
Alexander's research was part of the wider debate about how society should react to drug use, his hypothesis supporting the argument that social solutions, rather than medical or legal responses, are the best way to curb addictive behavior. However, his study was not well received by the mainstream scientific community. The two major biology journals Science and Nature rejected his paper, which eventually appeared in Pharmacology, Biochemistry and Behavior, a respectable but much smaller publication. Because of the paper's lukewarm reception, Simon Fraser University withdrew Rat Park's funding, and the experiment is now largely forgotten. http://en.wikipedia.org/wiki/Rat_Park