Information-based interventions to health behavior enjoy considerable popularity and are frequently used. This is so despite the fact that they often fail to successfully change health behavior. This article develops a transactional process model of human judgment and information processing that directs attention away from the mere accumulation of information to the needs, motives, and abilities of

the information user. It is argued that the model can be used to improve the effectiveness of information-based interventions. Two structural aspects of drug use images are discussed in detail: personal mental images related to drug use/abstinence and the selection of images pertinent to drug use. The developed model suggests what specific judgment and information-processing changes should occur as the result of successful information-based intervention.