ABSTRACT
A random-effects meta-analytic review of the effects of one-sided and two-sided persuasive messages identifies two key moderator variables: whether the two-sided message is refutational or nonrefutational and whether the message is consumer advertising or nonadvertising. Compared with one-sided messages, refutational two-sided messages on nonadvertising topics enjoy significantly greater credibility and persuasiveness, nonrefutational two-sided messages on nonadvertising topics are not significantly different in credibility and are significantly less persuasive, refutational two-sided messages on advertising topics do not differ significantly on either credibility or persuasiveness (though few relevant studies exist), and nonrefutational two-sided messages on advertising topics enjoy significantly greater credibility but do not differ in persuasiveness. Often-mentioned moderators (such as audience initial position and education) appear not to have substantial influence on sidedness effects. Explanations of the observed effects are explored, and foci for future research are identified.
