Sleeper Effects
Sleeper Effects
People receive hundreds of persuasive messages on a given day. Naturally, they discount a great majority of these messages by relying on cues such as the credibility of the message source. In general, it is expected that noncredible sources present invalid arguments. Therefore, communications associated with noncredible sources generally do not bring about substantial attitude change in response, and may be regarded as ineffective influence attempts. Decades of research on the sleeper effect, however, suggests that it would be misleading to reach that conclusion without measuring attitudes down the line again. People are not very good at remembering the original context of everything that they learn, and as a result, it is possible that they may continue to remember the message well but have a hard time remembering its source. Thus, forgetting the noncredible source of the message or simply dissociating it from the message may bring about a delayed increase in persuasion. This possibility, known as the sleeper effect, is counterintuitive because the impact of a persuasive message is usually greater at the time of exposure than some time after exposure.
As a data pattern, the sleeper effect was identified in the early 1930s. However, systematic study of the effect and its mechanisms started much later, in the 1950s (e.g., Hovland and Weiss 1951). During World War II Carl Hovland and colleagues were interested in evaluating the impact of propaganda films commissioned by the army on the morale and opinions of enlisted U.S. soldiers. In one of their studies (Hovland, Lumsdaine, and Sheffield 1949), soldiers watched a film from the Why We Fight series and reported their opinions either five days or nine weeks after exposure to the film. Measures of opinions taken five days after the presentation of the film suggested that the film did not have an impact on the opinions of the soldiers. When measured again nine weeks after exposure, however, the researchers found that the opinions of those who had watched the film shifted in the direction of advocacy, whereas the opinions of those who had not watched the film remained unchanged. Thus, the film had an effect, but it required some time to surface. The term sleeper effect was coined after this observation.
Several mechanisms have been considered to account for the effect. However, variants of the discounting cue explanation have been especially popular (for a review of primary explanations, see Kumkale and Albarracín 2004; see also Pratkanis, Greenwald, Leippe, and Baumgardner 1988). According to this theory, a noncredible message source induces suspicions of invalidity and temporarily decreases the impact of an otherwise persuasive message; consequently, little or no persuasion takes place at the time of exposure. Over time, though, the attitudes of the recipients shift in the direction of advocacy, either because the recipients forget the discounting information ( forgetting hypothesis ) or because they do not spontaneously associate the discounting cue with the message any longer ( dissociation hypothesis ). When they identified the sleeper effect for the first time, Hovland and colleagues (1949) suggested that the recipients might have forgotten the noncredible source of the message but remembered the message itself. In a follow-up study Hovland and Weiss (1951) found evidence for the sleeper effect again, but measures of recall for the message source suggested that the recipients could still remember the source of the message. Based on this finding, Hovland and colleagues proposed that forgetting the discounting cue was not necessary for the sleeper effect to take place; a weakened association between the message and the discounting cue could generate the effect as well. To the extent that the discounting cue becomes less accessible than the message over time, the likelihood of observing the sleeper effect should increase significantly. For several decades researchers concurred that the sleeper effect could be guided by either of these processes. Despite widespread acceptance of these earlier findings, subsequent research revealed that the effect might not be as strong or reliable as once thought. A recent synthesis of the relevant literature, however, revealed that the sleeper effect takes place reliably under certain circumstances, such as when the recipients deeply think about the communications at the time of receiving the communications (Kumkale and Albarracín 2004). At the very least, this synthesis verified that there is evidence for the sleeper effect in persuasion.
BIBLIOGRAPHY
Hovland, Carl I., and Walter Weiss. 1951. The Influence of Source Credibility on Communication Effectiveness. Public Opinion Quarterly 15: 635-650.
Hovland, Carl I., Arthur A. Lumsdaine, and Fred D. Sheffield. 1949. Experiments on Mass Communication. Princeton, NJ: Princeton University Press.
Kumkale, G. Tarcan, and Dolores Albarracín. 2004. The Sleeper Effect in Persuasion: A Meta-Analytic Review. Psychological Bulletin 130 (1): 143-172.
Pratkanis, Anthony R., Anthony G. Greenwald, Michael R. Leippe, and Michael H. Baumgardner. 1988. In Search of Reliable Persuasion Effects III: The Sleeper Effect Is Dead. Long Live the Sleeper Effect. Journal of Personality and Social Psychology 54 (2): 203-218.
G. Tarcan Kumkale