an experiment in which they tested the addictiveness of various substances (e.g. heroin) on lab rats. the twist was, the rats weren't just left alone in cages with the test substance, but placed in an environment with lots of other entertaining things for them to do and other rats to socialize with. in this environment, nicknamed Rat Park, the rats were much less prone to develop a dependence on the substance. "The opposite of addiction isn't sobriety; it's connection"