The Role of Distal Variables in Behavior Change: Effects of Adolescents' Risk for Marijuana Use on Intention to Use Marijuana.

This study uses an integrative model of behavioral prediction as an account of adolescents' intention to use marijuana regularly. Adolescents' risk for using marijuana regularly is examined to test the theoretical assumption that distal variables affect intention indirectly. Risk affects intention indirectly if low-risk and high-risk adolescents differ on the strength with which beliefs about marijuana are held, or if they differ on the relative importance of predictors of intention. A model test confirmed that the effect of risk on intention is primarily indirect. Adolescents at low and high risk particularly differed in beliefs concerning social costs and costs to self-esteem. Not surprisingly, at-risk adolescents took a far more positive stand toward using marijuana regularly than did low-risk adolescents. On a practical level, the integrative model proved to be an effective tool for predicting intention to use marijuana, identifying key variables for interventions, and discriminating between target populations in terms of determinants of marijuana use.

Targeting norm-related beliefs about marijuana use in an adolescent population.

The integrative model of behavior prediction and priming theory were used to evaluate the effects of anti-marijuana advertisements in an experimental context. In 1 original study and 2 replications, 435 adolescents were randomly assigned to condition, and those in the experimental condition viewed 3 ads that challenged undesirable normative beliefs about marijuana use. The results showed that ad exposure had small but positive (anti-drug) effects on adolescents' considerations of the outcomes of using marijuana and their perceptions of the social normative climate surrounding marijuana use. Priming effects also were observed but generally ran counter to predictions. Implications of the findings for anti-drug campaigns are discussed. Potential explanations for the unexpected priming effects also are offered.

The effectiveness of gateway communications in anti-marijuana campaigns.

Successful anti-marijuana messages can be hypothesized to have two types of effects, namely persuasion effects, that is, a change in people's beliefs about using marijuana, and priming effects, that is, a strengthened correlation between beliefs and associated variables such as attitude and intention. This study examined different sets of anti-drug advertisements for persuasion and priming effects. The ads targeted the belief that marijuana is a gateway to stronger drugs, a belief that is often endorsed by campaign planning officials and health educators. A sample of 418 middle and high school students was randomly assigned to a control video or one of three series of ads, two of which included the gateway message in either an explicit or implicit way. Results did not support the use of the gateway belief in anti-marijuana interventions. Whereas no clear persuasion or priming effects were found for any of the ad sequences, there is some possibility that an explicit gateway argument may actually boomerang. In comparison to the control condition, adolescents in the explicit gateway condition tended to agree less with the gateway message and displayed weaker correlations between anti-marijuana beliefs and their attitude toward marijuana use. The results suggest that the gateway message should not be used in anti-drug interventions.