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.
Bibliographical noteFunding Information:
Yzer is now at the Amsterdam School of Communications Research (ASCoR). Preparation of this manuscript was supported by NIDA grant 5 RO1 DA 12356-02. Address correspondence to Marco Yzer, ASCoR, University of Amsterdam, Kloveniers-burgwal 48, 1012 CX Amsterdam, The Netherlands. E-mail: email@example.com