unknown author. The Rat Park Experiment. Marin Mikulic website
In the late 1970s and early 1980s Bruce K. Alexander and other researchers run a series of experiments investigating the self-administration of morphine in rats firstly under a cage alienation and loneliness condition; then in a rat fun park condition, where there were other rats to associate and play with and engage in a number of playful activities. In both conditions rats were provided with two bottles: one contained just water and the other morphine in water. In the first instance rats consumed the morphine water to death; in the second they were interested in socialising mating and resisting to the morphine solution. The conclusion of these experiments confirmed that environmental and societal conditions are key in developing addictive behaviour, thus addiction.
References:
Alexander BK, Beyerstein BL, Hadaway PF, Coambs RB. Effect of early and later colony housing on oral ingestion of morphine in rats. Pharmacol Biochem Behav. 1981 Oct;15(4):571-6. doi: 10.1016/0091-3057(81)90211-2. PMID: 7291261.
Hadaway, P.F., Alexander, B.K., Coambs, R.B. et al. The effect of housing and gender on preference for morphine-sucrose solutions in rats. Psychopharmacology 66, 87–91 (1979). https://doi.org/10.1007/BF00431995
Rat Park drug experiment cartoon. (2013, May 29). Retrieved from http://www.stuartmcmillen.com/comics_en/rat-park/