Abstract: The sleeper effect is an intriguing and counter-intuitive phenomenon in the field of attitude change, which describes a persuasive influence that increases, rather than decays, over time. The research of the sleeper effect has made great progress in term of the scope, quality and profundity since first named by Hovland etc. in 1949. Three prevailing theoretical explanations have been advanced and tested: Dissociative Cue Hypothesis, Differential Decay Hypothesis, Availability-Valence Hypothesis. Conditions for observing the sleeper effect have been debated. The tendency of the future research is exploring the mechanism underlying the sleeper effect, integrating the sleeper effect into more general models of attitude change theories, applying the sleeper effect to the practices. In this article, the evolvement on sleeper effect research in west countries was reviewed within the theories advanced, the controversies raised and the trend of intending research.

Key words: attitude change (persuasion), sleeper effect, message, discount cue, source