This pattern of attitude change has puzzled social psychologists for nearly half a century, primarily due to its counter-intuitive nature and for its potential to aid in understanding attitude processes (Eagly & Chaiken, 1993). It has been a very widely studied phenomenon of persuasion research (Kumkale & Albarracín, 2004; see also Cook & Flay, 1978). Despite a long history, the sleeper effect has been notoriously difficult to obtain or to replicate, with the exception of a pair of studies by Gruder et al.