Interpersonal behavior in group discussion during marijuana intoxication.

Four-person groups of moderate and heavy marijuana users were studied in a group discussion situation during marijuana intoxication. Amount of participation and role behavior were compared to nonintoxicated baseline performance and to that of a no-drug control group. During intoxication, moderate users were less task-oriented and participated less in group discussion. These findings were interpreted in terms of cognitive, motivational, and physiological reactions to marijuana. The lack of any social effect on heavy users suggested the existence of behavioral tolerance.