Over the last 20 years, considerable progress has been made in advancing our theoretical understanding of the psychological effects of advertising. Early in this period, research focused on identifying mediators of advertising exposure on attitude formation and change. This research has indicated that the number of support and counterarguments generated during exposure to an advertisement (Wright, 1973), attitude toward the ad (Mitchell &Olson, 1981), and beliefs about the advertised product (Lutz, 1975) mediate attitude formation or change.

Later research concentrated on identifying factors that may influence the psychological processes that occur during exposure to advertising and how thse psychological processes affect attitude formation and change. One of the proposed models, the Elaboration Likelihood Model (Petty &Cacioppo 1983), for instance, identified message relevance as one of these factors. According to this model, when message relevance is high, individuals will actively process and evaluate the information in the advertisement when forming or changing attitudes. When message relevance is low, individuals will not actively process the information in the advertisement, but will instead rely on peripheral message cues to form or change attitudes.

Other models have identified goals or processing sets as a factor affecting the psychological processes that occur during exposure to advertising. Examples of the different alternative goals or processing sets that have been examined include a brand or advertisement processing set (e.g.,Gardner, 1985) and a utilitarian or value expressive set (Park &Young, 1986). Most of this research examining the psychological processes that precede attitude formation or change during exposure to an advertisement is integrated in a review by MacInnis and Jaworski (1989).