Marijuana and the perception of affect.

The influence of marijuana on the ability to perceive emotions in others was studied in 30 male volunteers who were experienced marijuana users. Subjects smoked either placebo or active marijuana containing 6 mg delta 9-THC. The Affective Sensitivity Scale, a test developed to measure the ability to perceive emotions in others, was divided at midpoint and the two halves were administered before and after smoking, respectively. Analysis of variance demonstrated a decline in test scores following active marijuana administration, while changes following the placebo treatment were not significant.