Abstract
INTRODUCTION: Attitudes of drug-abstinent youth considering marijuana initiation can be highly ambivalent. Invalidating pro-usage elements (i.e., opinions) of ambivalent marijuana attitudes, while leaving anti-marijuana elements intact, may create stronger, less ambivalent marijuana-resistant attitudes and lower usage intentions, while concurrently elucidating the role of ambivalence in persuasive prevention. METHOD: From an initial pool of marijuana-abstinent middle-school students (N = 538), the quintile expressing the most negative attitudes toward a marijuana prevention appeal (N = 101) were randomly assigned to one of three conditions designed to invalidate pro-marijuana opinions. Analyses then tested their susceptibility to a second marijuana prevention appeal. RESULTS: Personally threatening messages were found ineffective, but appeals contesting resistant responses significantly decreased ambivalence (p < .01). Mediational analyses showed that this decreased ambivalence was associated with less favorable attitudes and lower marijuana usage intentions (both p < .001). An attribution-based manipulation increased ambivalence (p < .05), which was associated with positive usage intentions mediated through positive attitudes (both p < .001). CONCLUSION: Analyses elucidated the role of attitude ambivalence in prevention, providing a more complete understanding of potential facilitative use of ambivalence in prevention models based on prevention. Results support the further examination and use of methods that invalidate pro-marijuana opinions, thereby leading to greater susceptibility to subsequent prevention appeals.