Marihuana or placebo cigarettes were smoked by 12 subjects in two environments, one "favorable" and one "neutral." The object was to determine the contribution of setting to the effects reported from the drug. Two quantifiable self-report measurements, the linear euphoriant scale and the card-sort version of the Addiction Research Center Inventory (marihuana and hallucinogen scales), were the major reporting criteria.
Analyses of variance consistently demonstrated strong effects for subjects and drug but not for the environmental conditions. Reports of marihuana effects may be assumed to be highly colored by psychological differences in the mental set of subjects, or biological variations in their responses to the drug. The actual environment in which the drug is taken seems to play little, if any, role.
Hollister LE, Overall JE, Gerber ML. Marihuana and Setting. Arch Gen Psychiatry. 1975;32(6):798-801. doi:10.1001/archpsyc.1975.01760240126010