The acute response to marijuana generally includes feelings of euphoria and relaxation (Hollister, 1986), and alterations of motor control, sensory function, sense of time and cognitive performance have been documented (Nahas, 1993). Studies of laboratory- controlled smoking of marijuana have reported dose-related effects on measures of heart rate, subjective feeling of being “high”, reports of being hungry, and on cognitive performance of tasks including digit span, divided attention, and recall (Chait et al., 1988; Chait et al., 1985; Haney et al., 1999a, b). Early studies of marijuana smokers reported that use of the drug also increased feelings of happiness, friendship, interpersonal warmth and empathy (Galanter et al., 1974; Tart, 1971), suggesting to the users a facilitation of interpersonal relationships. Interestingly, the marijuana-intoxicated subjects who were observed by raters blind to the subjects’ drug state reported that subjects’ use of marijuana actually decreased both social interaction (Galanter et al., 1974) and empathic communications (Janowsky et al., 1979). Despite this, marijuana smokers have reported an enhanced effect on sensory-perceptual abilities (Tinklenberg and Darley, 1976) and improved insight into others (Green et al.,
