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. (1978). Controversy about the existence of a "sleeper effect" One of the more challenging aspects that the sleeper effect posed to some researchers in early studies was the sheer difficulty of obtaining the effect. The sleeper effect is controversial because the influence of persuasive communication is greater when one measures the effect closer to the presentation instead of farther from the time of the reception. After attempting to replicate the effect and failing, some researchers suggested that it might be better to accept the null hypothesis and conclude that the sleeper effect does not exist. The sleeper effect is involved with initial message impression so the phenomenon has implications for models of persuasion, including teaching methods, as well as more recent conceptualizations, such as the heuristic-systematic model and the elaboration likelihood model. However, Cook and his associates responded by suggesting that previous studies failed to obtain the sleeper effect because the requirements for a strong test were not met. Specifically, they argued that the sleeper effect will occur only if: (a) the message is persuasive; (b) the discounting cue has a strong enough effect to suppress initial attitude change; (c) enough time has elapsed between immediate and delayed post-tests; and (d) the message itself still has an effect on attitudes during the delayed post-test. Experimental studies conducted did, in fact, provide evidence for the sleeper effect occurring under such theoretically relevant conditions. Furthermore, the sleeper effect did not occur when any of the four requirements were not met. According to the dissociation interpretation, a sleeper effect appears to happen when a convincing message is conferred with a discounting cue (such as a low-credible source or counterargument). A sleeper effect occurs because of an impulsive dissociation of a message and a discounting cue over time (contrasting to a simple forgetting of a source). First identified The sleeper effect was first identified in US Army soldiers during World War II, after attempts to change their opinions and morals. Carl Hovland et al. measured the soldier’s opinions five days or nine weeks after they were shown a movie presentation