Computer-Mediated Versus Face-to-Face Motivational-Type Interviews

Inclusion Criteria: * A brief eligibility questionnaire assessed each respondent's age, previous marijuana use, and ambivalence about their marijuana use during the year preceding the study. Sample ambivalence items included: "During the past year I've had mixed emotions about my level of marijuana use or nonuse," and "How much have you thought about changing your marijuana use or nonuse during the past year?" Responses options ranged from 0 ("not at all") to 5 ("medium amount") to 10 ("a lot"). Respondents who were 18-29 years of age and reported at least a "medium amount" of ambivalence in response to 2 or more ambivalence questions were eligible to participate in the study. Three types of adults were recruited: non-marijuana users, occasional marijuana users, and frequent marijuana users. Non-marijuana users were defined as individuals who reported no history of marijuana use in their lifetime. Occasional marijuana users were defined as individuals who used marijuana 1-5 times during the 2 months preceding the study but fewer than 24 times during the year preceding the study. Frequent marijuana users were defined as individuals who used marijuana more than 7 times during the 2 months preceding the study and more than 24 times during the year preceding the study. Exclusion Criteria: * We excluded participants who did not meet the above criteria.